Search found 104 matches
- Thu Mar 12, 2020 9:21 pm
- Forum: General Rate Laws
- Topic: Instantaneous and Average Rate
- Replies: 3
- Views: 296
Re: Instantaneous and Average Rate
Yes, at equilibrium, the forward and reverse reaction rates are equal which is the reason there is no change in the concentration of the products and the reactants. Also, the instantaneous rate is a more accurate measurement of the rates of the reactants and the products as it takes the smallest tim...
- Thu Mar 12, 2020 9:08 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Rate Constant and Shorter Half Life
- Replies: 5
- Views: 680
Re: Rate Constant and Shorter Half Life
For a first-order reaction, the half-life is equal to ln2/kr which means that when kr, the rate constant, increases, the half-life will decrease since kr is in the denominator and they are inversely proportional. The same proportion is true for the zeroth and second half-lives as they have kr in the...
- Thu Mar 12, 2020 9:03 pm
- Forum: Second Order Reactions
- Topic: Termolecular
- Replies: 43
- Views: 2392
Re: Termolecular
Termolecular reactions occur when the formation of the product depends on the collision between three reactants. For example, A + A + B --> C.
- Wed Mar 11, 2020 11:52 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Units for reaction rates
- Replies: 15
- Views: 1129
Re: Units for reaction rates
The unit for k for a zeroth-order reaction is moles per liter per second since the power of the concentration of the reactant is zero and the rate value must have the rate in moles per liter per second. For a first-order reaction, the rate is equal to the rate constant x the concentration of the rea...
- Wed Mar 11, 2020 11:31 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts and Reaction Pathways
- Replies: 6
- Views: 454
Re: Catalysts and Reaction Pathways
The forward and reverse reaction proceed by the same mechanism which means that if the forward reaction is facilitated, the reverse is also facilitated.
- Wed Mar 11, 2020 11:29 am
- Forum: Zero Order Reactions
- Topic: Zero Order
- Replies: 8
- Views: 516
Re: Zero Order
A zeroth-order reaction has a rate that does not depend on the concentration of any of the reactants but takes place at the same rate no matter the concentration of the reactant. For example, the reaction takes place at the same rate when reactant A's concentration is 1/2 of its initial concentratio...
- Sun Mar 08, 2020 10:26 pm
- Forum: Zero Order Reactions
- Topic: Zero Order Reaction Example
- Replies: 6
- Views: 1359
Re: Zero Order Reaction Example
A zeroth-order reaction has a rate that does not depend on the concentration of the reactant. This is commonly observed in enzyme-catalyzed reactions when the enzyme is saturated with the substrate and increasing the substrate has no effect on the rate of the reaction since there are no more enzymes...
- Sun Mar 08, 2020 10:22 pm
- Forum: General Rate Laws
- Topic: Rate constant vs. rate
- Replies: 4
- Views: 308
Re: Rate constant vs. rate
The rate constant shows the relation between the concentration of a reactant and the rate of a reaction. The rate of a reaction depends on the concentration of the reactant with a proportionality constant of the rate constant. Because the proportionality between the rate of the reaction and the conc...
- Sun Mar 08, 2020 10:18 pm
- Forum: General Rate Laws
- Topic: Rate limiting step
- Replies: 12
- Views: 861
Re: Rate limiting step
The rate-limiting step is the slowest step in a reaction. The slowest step determines the overall rate of the reaction since the completion of the reaction depends on that step. For example, if you have a three-step reaction where the first step has a rate of 80 moles per liter per second, the secon...
- Sun Mar 08, 2020 10:07 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Temperature
- Replies: 4
- Views: 298
Re: Temperature
As the temperature increases, the kinetic energy of the particles in the reaction increases. This causes more collisions to occur between the reactants which cause the reaction to proceed at a faster rate and the activation energy to be lowered which is the minimum amount of energy required to drive...
- Sun Mar 08, 2020 10:03 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Instantaneous Rate
- Replies: 41
- Views: 2268
Re: Instantaneous Rate
The instantaneous rate decreases as the reaction proceeds because the reactants are consumed and less amount of reactant is left in the reaction which causes the rate of the reaction to decrease since the number of collisions between the reactants decreases and the change in the reactant concentrati...
- Sun Mar 01, 2020 11:20 pm
- Forum: General Rate Laws
- Topic: tangent lines
- Replies: 5
- Views: 460
Re: tangent lines
Yes. To find the slope of the tangent line you would have to either take a very small time step and divide the difference of the variables at those two time values and divide them by the time step. Another way to do it would be to take the limit of the difference of the variables at two times divide...
- Sun Mar 01, 2020 11:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Direction of flow
- Replies: 5
- Views: 454
Re: Direction of flow
I think the electrons can only flow from the anode to the cathode since oxidation always takes place in the anode and reduction in the cathode. The salt bridge exists to counteract the charge imbalance created by the one-way flow of the electrons. If the electrons could flow both ways, there would b...
- Sun Mar 01, 2020 11:08 pm
- Forum: General Rate Laws
- Topic: Differential Rate Law
- Replies: 3
- Views: 303
Re: Differential Rate Law
The differential rate law provides the relationship between the rate of a reaction and the concentration of the reactant. This determines the dependence of a reaction on the concentration of a specific reactant by giving the contribution of each reactant to the overall rate of the reaction.
- Sun Mar 01, 2020 11:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 12
- Views: 696
Re: Salt Bridge
Since the electron flow between the cathode and the anode depends partly on the charge difference between the two solutions in the way that a slightly positive or negative charge may attract or repel the electron and prevent the flow of the electron from the anode to the cathode. This would result i...
- Sun Mar 01, 2020 10:53 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Reducing/oxidizing agent
- Replies: 8
- Views: 574
Re: Reducing/oxidizing agent
If a species is being oxidized, this means it had lost an electron which has to be donated to another species. Because an electron lost by a species has to be gained by another species. Therefore, a species has to be reduced while the other is being oxidized. The species that is oxidized is the caus...
- Sun Feb 23, 2020 10:18 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Potential intensive property
- Replies: 2
- Views: 231
Re: Cell Potential intensive property
The cell potential does not depend on the number of moles of an element. For example, if we have A2+ + 2e --> A, the cell potential does not change when the number of moles of A increases. For example, multiplying the equation with 2, 2A2+ + 4e --> 2A still has the same cell potential. However, when...
- Sun Feb 23, 2020 10:18 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Potential intensive property
- Replies: 2
- Views: 231
Re: Cell Potential intensive property
The cell potential does not depend on the number of moles of an element. For example, if we have A2+ + 2e --> A, the cell potential does not change when the number of moles of A increases. For example, multiplying the equation with 2, 2A2+ + 4e --> 2A still has the same cell potential. However, when...
- Sun Feb 23, 2020 10:08 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation?
- Replies: 10
- Views: 702
Re: Oxidation?
Oxidation is the loss of electrons. In order to determine which species has lost an electron, you need to know the oxidation states of the elements you are dealing with. For example, oxygen has an oxidation state of -2 in H2O whereas hydrogen has an oxidation state of -1. By looking at the oxidation...
- Sun Feb 23, 2020 9:13 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Work
- Replies: 5
- Views: 368
Re: Work
The work done on a system is always positive since energy is spent on the system and the system gains the energy spent whereas the work done by the system is negative since the system spends energy and it is lost to its surroundings which gain this energy.
- Sun Feb 23, 2020 9:01 pm
- Forum: Balancing Redox Reactions
- Topic: Flow of electrons
- Replies: 11
- Views: 817
Re: Flow of electrons
It always goes from the anode to the cathode in a Galvanic cell since the anode is negatively charged and the cathode is positively charged and will attract the electrons from the anode. However, in an electrolytic cell, the cathode and anode do not have the same charges, regardless the electron sti...
- Sun Feb 23, 2020 8:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Why are exothermic reactions generally spontaneous?
- Replies: 16
- Views: 1244
Re: Why are exothermic reactions generally spontaneous?
According to the laws of thermodynamics, the entropy of a system always tends to increase. This is because when entropy increases, the number of states a particle can be found in increases which removes the constrains on that particle that stores potential energy. Imagine a gas in a small container....
- Sun Feb 23, 2020 8:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode vs Anode
- Replies: 11
- Views: 947
Re: Cathode vs Anode
A cathode is a positively charged electrode which the electrons flows toward because of its positive charge. An anode is a negatively charged electrode which the electron flows from because of its negative charge. These hold true for cathodes and anodes for a Galvanic cell. Oxidation is the loss of ...
- Wed Feb 12, 2020 3:05 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pizza Rolls #5
- Replies: 5
- Views: 397
Re: Pizza Rolls #5
For Part A, you have to add up three different delta S values to find the total change of entropy in the system. This includes deltaS for H2 container expansion, deltaS of Krypton gas for container expansion, and deltaS based on temperature change. Since entropy is a state function, this allows us ...
- Tue Feb 11, 2020 4:32 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Why are exothermic reactions generally spontaneous?
- Replies: 16
- Views: 1244
Re: Why are exothermic reactions generally spontaneous?
When a reaction is exothermic, the delta G is negative. In order for delta G to be negative, the change in enthalpy must be smaller and the change in entropy must be greater. This is because the term delta H does not have a negative sign in front of it which means that if it is increased, delta G in...
- Tue Feb 11, 2020 4:20 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G and spontaneity
- Replies: 4
- Views: 340
Re: Delta G and spontaneity
If you have a delta G that is negative which means that the reaction is spontaneous, then the reaction does not need energy to proceed. In other words, it will occur on its own without any external intervention. Because this reaction occurs spontaneously without the input of energy, this means that ...
- Mon Feb 10, 2020 9:35 pm
- Forum: Phase Changes & Related Calculations
- Topic: Work (w)
- Replies: 8
- Views: 375
Re: Work (w)
Work is not a state property because the work you have done does not depend on the difference between the final state and the initial state. For example, you may go up a hill along a straight path and you may also go up the hill in a rocky path that increases the distance between the ground and the ...
- Mon Feb 10, 2020 9:27 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: pH
- Replies: 3
- Views: 164
Re: pH
An acid is weak if it does not dissociate fully. When an acid dissociates only partially, the concentration of the hydrogen atoms released into the surrounding solution is less than a strong acid. Because the concentration of the hydrogen atoms is less than it would be if it dissociated fully, the p...
- Mon Feb 10, 2020 9:20 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous delta G
- Replies: 7
- Views: 440
Re: Spontaneous delta G
When delta is smaller than zero, the reaction is spontaneous, meaning that it will occur without energy input. We knew that delta G must have been spontaneous, but we did not know the exact temperature at which it would turn spontaneous. The critical point here is delta G = 0 since it is the point a...
- Sun Feb 09, 2020 11:58 pm
- Forum: Calculating Work of Expansion
- Topic: q=C delta T
- Replies: 5
- Views: 1394
Re: q=C delta T
q = C delta T gives the heat capacity whereas q = m C delta T gives the specific heat per 1 gram of the substance since there is multiplication with the grams of the substance.
- Sun Feb 09, 2020 11:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q and K
- Replies: 3
- Views: 249
Re: Q and K
K is the constant that gives the ratio of equilibrium concentrations of a reaction whereas Q gives the ratio of the concentration of the products to the reactants at any given point in time as the reaction is occurring. They are both calculated the same way, however, Q can be calculated at any point...
- Sun Feb 09, 2020 11:44 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Boltzmann equation
- Replies: 5
- Views: 223
Re: Boltzmann equation
The Boltzmann equation gives the relationship between the entropy of a system and the number of different ways or microstates that the system can be arranged on energy levels which is w.
- Sun Feb 09, 2020 11:35 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Spontaneous vs Favorable
- Replies: 8
- Views: 467
Re: Spontaneous vs Favorable
When a reaction is spontaneous, it does not require a net input of energy to occur. For example, the melting of ice occurs spontaneously, or the diffusion of air does not require an effort whereas performing these reactions in the reverse direction would require an effort. When a reaction is spontan...
- Sun Feb 09, 2020 11:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy change
- Replies: 3
- Views: 265
Re: Enthalpy change
When the reaction is reversed, your initial products will become the new reactants and initial reactants will become new products so if A + B --> C where the enthalpy of the product C is greater than the reactants, then the reverse will be C --> A + B. Since enthalpy is calculated as the enthalpy of...
- Wed Jan 29, 2020 10:32 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume and Pressure
- Replies: 8
- Views: 280
Re: Volume and Pressure
Volume and pressure are inversely related so when the pressure increases, the volume decreases, and when pressure decreases, volume increases. For example, when the volume of a container is decreased, the same moles of gas will be contained in a smaller volume, thus increasing the pressure they appl...
- Wed Jan 29, 2020 10:27 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Temperature
- Replies: 14
- Views: 567
Re: Temperature
Since delta H is equal to the energy of products - reactants, if delta H is positive, the energy of the products will be larger than the energy of the reactants meaning that there is an input of energy and the reaction is endothermic. If the energy of the reactants is greater than the energy of the ...
- Wed Jan 29, 2020 10:23 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: temperature
- Replies: 4
- Views: 178
Re: temperature
I think it depends on the units of the elements. Usually, the temperature is given in degrees Celsius and so is the specific heat or heat capacity. So you do not have to convert it to kelvin.
- Mon Jan 27, 2020 10:38 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: "Breaking bonds is always endothermic"
- Replies: 6
- Views: 1002
Re: "Breaking bonds is always endothermic"
The breaking of bonds always requires energy. However, the overall heat change of the system also takes into account other factors. For instance, the breaking of the bond between two phosphates in the decomposition of ATP into ADP and inorganic phosphate requires an energy input and is therefore end...
- Mon Jan 27, 2020 10:30 am
- Forum: Phase Changes & Related Calculations
- Topic: State functions
- Replies: 5
- Views: 261
Re: State functions
Heat is not a state function because it does not depend on the initial and final conditions of a system. For example, enthalpy which describes the change in the heat of the system depends on the difference between the final and initial state of the system. Therefore, as long as the final and initial...
- Mon Jan 20, 2020 12:45 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding a catalyst
- Replies: 7
- Views: 315
Re: Adding a catalyst
Adding a catalyst does not change the equilibrium because it is a kinetic property that favors both the forward and reverse reactions at the same rate and does not change the coefficients. The system may reach equilibrium faster but the equilibrium concentrations will not change. For example, reacti...
- Mon Jan 20, 2020 12:38 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Shifts vs Different K values
- Replies: 3
- Views: 195
Re: Shifts vs Different K values
At constant temperature, changing the concentration, pressure or volume will not change the K value. This is because the system will shift to counteract the stress and balance itself once again. For example if you decrease the amount of products, the numerator of K will go down but it will be counte...
- Mon Jan 20, 2020 11:12 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier Principle
- Replies: 4
- Views: 260
Re: Le Chatelier Principle
I think temperature changes the equilibrium constant because it favors either endothermic or exothermic reactions. For example, if we have a reaction A + B --> C, and the forward reaction is endothermic, changing the temperature will favor the forward reaction. As the equilibrium constant indicates ...
- Mon Jan 20, 2020 10:55 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Endothermic vs Exothermic
- Replies: 7
- Views: 321
Re: Endothermic vs Exothermic
I think you can tell by looking at the hear input of output if it is given, or you could look at whether there is bond formation or the breakage of bonds which would indicate whether energy is needed or released. By looking at the energy of the products and the reactants you can determine that the r...
- Mon Jan 20, 2020 10:52 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% rule
- Replies: 3
- Views: 122
Re: 5% rule
The coefficients are taken into account when calculating the concentration of the reactants and the products. Once you have done that, I don't think you need to consider the coefficients again. For example, if you have calculated that there was x amount of product at equilibrium and y amount initial...
- Sun Jan 19, 2020 9:34 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: le chatelier's principle
- Replies: 3
- Views: 145
Re: le chatelier's principle
Le Chatelier's Principle states that when there is a stress that is a applied to a system such as temperature, pressure, or concentration changes, the system will counteract this stress and balance itself again. For example, if I increase the concentration of the reactants, the concentration of the ...
- Fri Jan 17, 2020 3:25 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Temperature Change
- Replies: 9
- Views: 602
Re: Temperature Change
The product is favored when the reaction is endothermic because the forward reaction requires the input of energy and that required energy is provided excessively by the increase in temperature. In endothermic reactions, the heat is on the reactants side since it is an input. Therefore, when the tem...
- Thu Jan 16, 2020 5:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid/ Base Ionization
- Replies: 2
- Views: 187
Re: Acid/ Base Ionization
Acids and bases that completely ionize dissociate completely and release hydrogen or hydroxide ions to the solution whose molarities are equal to the molarity of the acid (by taking into account the stoichiometric coefficients). This means that the acid or the base has completely given off its hydro...
- Thu Jan 16, 2020 5:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid Strength and Oxidation Number
- Replies: 2
- Views: 468
Re: Acid Strength and Oxidation Number
I think the acid strength increases as the oxidation number of the central atom increases since the central atom will be more electronegative and pull the electrons away from the surrounding atoms which results in a weaker bond between the central and surrounding atom that makes it easier for the su...
- Thu Jan 16, 2020 5:15 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endo/Exothermic Reactions
- Replies: 6
- Views: 388
Re: Endo/Exothermic Reactions
I think it depends on the case and the overall heat change of the system. But since, energy in the form of heat is required to break the bonds, it is most likely that the reaction will be endothermic and require energy. This cannot be generalized though. For example, the dissociation of ATP to ADP a...
- Thu Jan 16, 2020 5:07 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endo/Exothermic Reactions
- Replies: 6
- Views: 388
Re: Endo/Exothermic Reactions
I think it depends on the case and the overall heat change of the system.
- Sun Jan 12, 2020 4:20 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in pressure
- Replies: 4
- Views: 259
Re: Changes in pressure
When we consider a change in pressure, we assume a constant concentration of the reactants even though the volume has changed. When you increase the pressure, the volume decreases, and so there will be the same amount of reactants as there were in the first place but the volume they occupy has decre...
- Sat Jan 11, 2020 4:04 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction quotient
- Replies: 8
- Views: 422
Re: Reaction quotient
The reaction quotient is used to calculate the ratio of the reactant and product concentrations at any point as the reaction takes place. When the reaction quotient equals the equilibrium constant k, the reaction reaches equilibrium. Thus, the reaction quotient is used to calculate whether the forwa...
- Sat Jan 11, 2020 3:56 pm
- Forum: Ideal Gases
- Topic: Solids and Liquids [ENDORSED]
- Replies: 10
- Views: 572
Re: Solids and Liquids [ENDORSED]
Solids and liquids are excluded from the equilibrium constant expression because their concentration equals their density divided by their molar mass. Since the density of a pure solid or liquid is constant regardless of how much solid or liquid is present, their concentrations stay constant through...
- Thu Jan 09, 2020 2:37 pm
- Forum: Ideal Gases
- Topic: K value
- Replies: 14
- Views: 1178
Re: K value
The K value is the equilibrium constant which is calculated by the concentration of the products divided by the concentration of the reactants at equilibrium. When the K value is large, this means that then the concentration of the products which is in the numerator is significantly larger than the ...
- Fri Dec 06, 2019 1:37 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation Number
- Replies: 2
- Views: 355
Re: Oxidation Number
You can also figure out the oxidation number of atoms by looking at the oxidation number of other atoms in a molecule. For example, we know that the oxidation number of oxygen is -2 so we can find the oxidation number of another atom that is bound to oxygen by making the overall oxidation number equ...
- Fri Dec 06, 2019 1:22 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: H bonding
- Replies: 4
- Views: 396
Re: H bonding
Yes, when determining points of hydrogen bonding, lone pairs are also considered if it is on an N, O, or F as well as the hydrogens since the hydrogens will form a bond with those electronegative atoms.
- Wed Dec 04, 2019 12:39 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: pH of salt solutions
- Replies: 2
- Views: 155
Re: pH of salt solutions
The ability of an ion to change the pH of the solution depends on what it is a conjugate of. If you have a strong acid and a weak base, the base will be protonated and the resulting compound will have be a strong conjugate acid so the salt solution will be acidic. For example, if we titrate a strong...
- Mon Dec 02, 2019 1:47 pm
- Forum: Conjugate Acids & Bases
- Topic: Conjugate vs Bronsted acids/bases
- Replies: 4
- Views: 265
Re: Conjugate vs Bronsted acids/bases
Bronsted acids and bases refer to the substances that are considered as acids and bases based on the Bronsted definition which means that a substance that is considered an acid would be the proton donor and a substance that is considered a base would be the proton acceptor. Conjugate acids and bases...
- Mon Dec 02, 2019 12:37 pm
- Forum: Bronsted Acids & Bases
- Topic: Self-test6A.2B
- Replies: 3
- Views: 297
Re: Self-test6A.2B
Because Bronsted acids are defined to be the molecules to that donate a proton (H atom), NH4+ would be the Bronsted acid here as it is the one that donated a proton to HCO3- and became NH3. Lewis acids are defined to be the lone pair acceptors so NH4+ would be considered a Lewis acid since it is pos...
- Wed Nov 27, 2019 1:16 pm
- Forum: Lewis Acids & Bases
- Topic: What is the correct definition of a base?
- Replies: 5
- Views: 378
Re: What is the correct definition of a base?
There are two definitions for both acids and bases. These are Bronsted acid and bases and Lewis acid and bases, both of which define an acid and a base in a different way. A Bronsted acid is a substance that donates hydrogen ions to the solution it is found in, whereas a Bronsted base is a substance...
- Wed Nov 27, 2019 1:03 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric characteristics
- Replies: 3
- Views: 302
Re: Amphoteric characteristics
Amphoteric molecules have the characteristics of both acids and bases. This means that they are able to act as acids or bases depending on the circumstances and what they are reacting with. Amphoteric substances are usually created by metalloids which also have the characteristics of both metals and...
- Wed Nov 27, 2019 12:43 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Acid/base strength?
- Replies: 4
- Views: 418
Re: Acid/base strength?
The strength of an acid or base is determined by its ability to dissociate in water. A strong acid would completely dissociate in the water, yielding a hydronium ion of the same concentration as the concentration of the acid itself. For example, HCl would dissociate completely into hydrogen and chlo...
- Wed Nov 27, 2019 12:26 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bonding Sites
- Replies: 9
- Views: 578
Re: Hydrogen Bonding Sites
Hydrogen bonding sites are where hydrogen bonding can occur. This includes hydrogen atoms that are bound to electronegative atoms like F, N, or O. A hydrogen bound to one of these elements would be a potential site for hydrogen bonding as well as the nitrogen, fluorine, and oxygen atoms bound to hyd...
- Tue Nov 26, 2019 5:44 pm
- Forum: Biological Examples
- Topic: cisplatin
- Replies: 3
- Views: 312
Re: cisplatin
Yes. You need to know the difference between cis and transplatin and how one can play an important biological role while the other cannot despite the fact that they both have the same composition. Cis-platin has its two chlorine atoms on one side, meaning that they are not on opposite sides. This br...
- Wed Nov 20, 2019 1:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Difference between Electorn arrangement and VSEPR
- Replies: 5
- Views: 455
Re: Difference between Electorn arrangement and VSEPR
There is a difference between the electron configuration of a molecule and the shape of the molecule. While the electron configuration takes lone pairs into accounts as well due to the fact that they are regions of electron density as well, however, the shape of the molecule solely depends on the po...
- Wed Nov 20, 2019 12:58 pm
- Forum: Hybridization
- Topic: Is hybridized orbitals all weighed equally in character?
- Replies: 4
- Views: 218
Re: Is hybridized orbitals all weighed equally in character?
Hybridized orbitals have an energy between the orbitals of which they are composed. So sp3 has 3 hybridized orbitals of equal character that have an energy in between the energy of s orbital and the energy of p orbital. I do not think that the hybridized orbitals have any energy difference among eac...
- Mon Nov 18, 2019 1:21 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs covalent
- Replies: 2
- Views: 270
Re: Ionic vs covalent
The best way to determine ionic and covalent bonds would be looking at electronegativity difference between the atoms in the bond and also the polarizability of the atoms which will contribute to the covalent and ionic bond character of the bond. When the polarizability of the anion increases, and t...
- Mon Nov 18, 2019 1:04 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma vs Pi
- Replies: 11
- Views: 736
Re: Sigma vs Pi
Sigma bonds overlap end-to-end to form a bond, whereas pi bonds form by overlapping side-by-side with each other. A significant difference is that sigma bonds allow rotation of atoms, whereas the pi bonds break if one of the atom rotates. Also, sigma bonds are more stable than pi bonds and form befo...
- Mon Nov 18, 2019 1:00 pm
- Forum: Hybridization
- Topic: HW Question 2F15
- Replies: 1
- Views: 239
Re: HW Question 2F15
I think the bond angles increases from sp3 to sp2 because number of hybrid orbitals = number of regions of electron density. So, if you have sp3 you have 4 regions of electron density as you have 4 hydrid orbitals, whereas when you have sp2 you have 3 regions of electron density as you have 3 hydrid...
- Fri Nov 15, 2019 1:50 pm
- Forum: Dipole Moments
- Topic: London forces
- Replies: 9
- Views: 549
Re: London forces
London dispersion forces or induced dipole-induced dipole interactions are universal because this type of interaction occurs between any two molecules due to the fluctuating electron densities of the individual atoms of a molecule which results in temporarily positively charged and negatively charge...
- Fri Nov 15, 2019 1:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining Lone Pair Location
- Replies: 3
- Views: 158
Re: Determining Lone Pair Location
Knowing the exact location of lone pairs would be difficult but one guideline would be balancing the distance between lone pairs and the bonding electrons since they will all repel each other as they are regions of electron density. Lone pair-lone pair repulsion will be the greatest, the lone pair-b...
- Fri Nov 15, 2019 1:28 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bond
- Replies: 7
- Views: 413
Re: Hydrogen Bond
Hydrogen bonds occur between the hydrogen that is bound to an electronegative atom like fluorine, nitrogen, oxygen, and fluorine, nitrogen, or oxygen that are partially charged. For example, hydrogen bonding occurs between the water molecules between partially negatively charged oxygen and partially...
- Fri Nov 15, 2019 1:15 pm
- Forum: Dipole Moments
- Topic: Shape of Molecules affect boiling point?
- Replies: 7
- Views: 909
Re: Shape of Molecules affect boiling point?
Rod-shaped molecules have higher boiling points than spherical molecules because of the heightened interactions between the molecules. Boiling points depend on the strength of intermolecular forces. When a molecule is more linear as in the case of rod-shaped molecules, it will have a larger surface ...
- Fri Nov 15, 2019 1:01 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: induced dipoles
- Replies: 5
- Views: 351
Re: induced dipoles
Induced dipole-induced dipole interactions are a result of fluctuating electron densities. For example, if you put two nonpolar molecules together that do not contain any dipoles in their bonds, there would be no interaction between the molecules that was due to a difference in charges such as parti...
- Wed Nov 06, 2019 3:23 pm
- Forum: Ionic & Covalent Bonds
- Topic: Why is the ionization energy of nitrogen higher than that of oxygen's?
- Replies: 11
- Views: 1008
Re: Why is the ionization energy of nitrogen higher than that of oxygen's?
The reason lies in the electron configuration of the oxygen atom. Oxygen has 6 valence electrons in its n = 2 shell. 2 of these electrons will occupy the 2s subshell while the remaining 4 will occupy the 2p subshell. Because 2p subshell has 3 orbitals, the oxygen atom will have 1 pair of electrons i...
- Wed Nov 06, 2019 12:42 pm
- Forum: Properties of Light
- Topic: De Broglie for Photon?
- Replies: 3
- Views: 266
Re: De Broglie for Photon?
The De Broglie equation only applies to particles that have a resting mass and therefore cannot be applied to light. Light is just electromagnetic radiation, and photons are discrete packets of energy that have no mass. To find the wavelength of light, you will need to use the c = lambda x frequency...
- Wed Nov 06, 2019 12:38 pm
- Forum: Trends in The Periodic Table
- Topic: Effect of Charge on an Atom
- Replies: 2
- Views: 259
Re: Effect of Charge on an Atom
The polarizability of an anion is dependent on the number of electrons it has which is also dependent on the neutral state of the atom and the nuclear charge. The more electrons an atom has, the greater its electron cloud and the more electrons that are further away from the nucleus which may be att...
- Wed Nov 06, 2019 12:34 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: orbitals vs. subshells
- Replies: 4
- Views: 562
Re: orbitals vs. subshells
Subshells are 1s, 2p, ... Orbitals are px, py, pz, dx, ... So, for example, the px orbital can accommodate up to 2 electrons. Each orbital can be occupied by a maximum of 2 electrons each with opposite spin. For n = 2 There are 2 subshells (2s, 2p), and a total of four orbitals (one s, and 3 p orbit...
- Wed Nov 06, 2019 12:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: C, N, O, and F
- Replies: 13
- Views: 643
Re: C, N, O, and F
Yes, they have to follow the octet rule because they cannot have an expanded octet since they are in the second period and do not have the shell n=3. Therefore, they do not possess a d orbital which can hold up to 10 electrons and therefore allow the atom to expand its octet. Atoms in the first and ...
- Wed Oct 30, 2019 5:52 pm
- Forum: Trends in The Periodic Table
- Topic: Noble Gas
- Replies: 4
- Views: 178
Re: Noble Gas
When lookıng at a trend, to determine whether the noble gases are included, you should consider the properties of noble gases. Since the atomic radius is a general concept it can be applied to noble gases as well. Electronegativity does not apply because it is defined as the pull the nucleus of an a...
- Wed Oct 30, 2019 12:43 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Question 1E 1
- Replies: 3
- Views: 218
Re: Question 1E 1
The answers would not change for H because the electron would still move to a higher energy level, and move to a different orbital. This change would result in the expansion of the atom which would cause the radius of the atom to increase in both scenarios. Therefore, the energy of the electron has ...
- Wed Oct 30, 2019 12:34 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability and Electronegativity
- Replies: 2
- Views: 390
Re: Polarizability and Electronegativity
I don't think there is a clear relationship between polarizability and electronegativity since polarizability depends on the type of atoms involved in the bonding as well. Roughly, we could say that as the electronegativity increases, the pulling of electron by an atom increases and therefore it has...
- Wed Oct 30, 2019 9:14 am
- Forum: Ionic & Covalent Bonds
- Topic: 2A.5 (d-block configurations)
- Replies: 4
- Views: 195
Re: 2A.5 (d-block configurations)
The 3d subshell is high in energy compared to the 4s subshell when the 4s subshell is unfilled with electrons. Once the 4s subshell has been filled, however, the 4s subshell will become higher in energy, and the next subshell to be filled will be the 3d. Even though 3d subshell had higher energy ini...
- Tue Oct 22, 2019 12:19 am
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 6
- Views: 312
Re: Electron Affinity
Electron affinity is the desire of an atom to receive an electron or the energy that is released when an electron is added to an atom. It increases from left to right and bottom to top, same as ionization energy, because the atomic radius decreases which increases the electrostatic interactions of t...
- Mon Oct 21, 2019 11:56 pm
- Forum: Trends in The Periodic Table
- Topic: Metals, Nonmetals, Metalloids
- Replies: 5
- Views: 468
Re: Metals, Nonmetals, Metalloids
Metalloids have a characteristic diagonal pattern in the periodic table, so if you start with boron and follow a diagonal pattern until you reach a noble gas, specifically Og, and then add Sb and Ge which are the only ones left out, you can easily find out the metalloids. The elements to the right o...
- Mon Oct 21, 2019 11:52 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s before 3d
- Replies: 4
- Views: 235
Re: 4s before 3d
The 4s orbital has lower energy than the 3d orbital when it is unoccupied by electrons. Because electrons always fill the lower energy level first, 4s orbital will be filled before 3d. After 4s orbital has been occupied by electrons, the 3d orbital will be filled which will shield the 4s electrons f...
- Mon Oct 21, 2019 11:20 pm
- Forum: DeBroglie Equation
- Topic: Velocity
- Replies: 13
- Views: 954
Re: Velocity
As far as we know, nothing can be faster than light, so if the speed of an electron, proton, or a neutron is faster than speed of light, there must have been an error in the calculations. The reason for nothing being greater than the speed of light is due to the absolute space-time in physics which ...
- Mon Oct 21, 2019 10:48 pm
- Forum: Einstein Equation
- Topic: 1B.15)
- Replies: 4
- Views: 213
Re: 1B.15)
I think you cannot calculate the E = hc/lambda equation because it is defined for light. The calculations we did always assigned the speed of light to c. In that case, you could use it for calculating the energy of a photon but cannot use it for any other particle. The reason we use lambda = h/mv is...
- Wed Oct 16, 2019 7:45 am
- Forum: Properties of Light
- Topic: 1A.6
- Replies: 3
- Views: 228
Re: 1A.6
Radio waves have the lowest frequency, infrared radiation has lower frequency and longer wavelength than visible light and is usually emitted in the form of heat so it is has lower energy, visible light can be thought of as a transition spectrum between the infrared and the ultraviolet radiation, ha...
- Wed Oct 16, 2019 7:36 am
- Forum: Properties of Light
- Topic: The extent of the change in the electrical field
- Replies: 2
- Views: 157
Re: The extent of the change in the electrical field
I think the extent of the energy change means the perturbation caused to the electrical field due to the oscillations of the electromagnetic wave. The extent of the change is proportional to the energy of the wave. The higher the energy, the greater the effect of the wave on the field, since greater...
- Wed Oct 16, 2019 7:22 am
- Forum: Properties of Electrons
- Topic: Intensity vs. Energy
- Replies: 10
- Views: 438
Re: Intensity vs. Energy
The intensity of a wave is defined by the number of photons it contains. The energy of the wave, however, refers to its frequency as the energy of the photons only increases with an increase in frequency. For example, when the intensity of the wave was increased in the photoelectric experiment for l...
- Tue Oct 15, 2019 12:25 am
- Forum: Properties of Light
- Topic: Wave Frequency
- Replies: 9
- Views: 503
Re: Wave Frequency
Frequency is the total energy of a single photon in the wave model since as we have seen in the photoelectric experiments, there is a certain amount of energy needed to remove electrons from the surface of a metal, called the threshold energy. The energy of the photon must be equal to or greater tha...
- Tue Oct 15, 2019 12:18 am
- Forum: *Shrodinger Equation
- Topic: Hamiltonian
- Replies: 1
- Views: 70
Re: Hamiltonian
Hi, so I asked the same question today, and Prof. Lavelle told me that the double derivate of sin would indeed be -sin, but the double derivate of theta is also negative so the negative signs cancel each other out, and therefore the final product is positive.
- Tue Oct 08, 2019 3:33 pm
- Forum: Balancing Chemical Reactions
- Topic: Question about hydroxide
- Replies: 5
- Views: 1693
Re: Question about hydroxide
Calcium has a +2 charge whereas hydroxide has a -1 charge. Because compounds are always neutral, there must be enough of both elements to cancel out the charges. This means that there should be a total of -2 charge for hydroxide to cancel out the +2 charge of calcium. Therefore, there must be 2 hydr...
- Tue Oct 08, 2019 3:00 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect Post Video Assessment
- Replies: 3
- Views: 280
Re: Photoelectric Effect Post Video Assessment
Hi, we know that E(photon) - Work function = Ek(electron) We know that the work function is 7.22x10^-19J. We also know that the wavelength of the incoming light is 194 nm which is 194 x 10^-9 m. To calculate the energy of the photon, we need to use the equation E = hv. So we need to know the frequen...
- Tue Oct 08, 2019 1:05 am
- Forum: Empirical & Molecular Formulas
- Topic: Test 1 Outline Question
- Replies: 4
- Views: 230
Re: Test 1 Outline Question
Molecules can be represented in various ways. For example, you could write the formula for the molecule like H2O, or you could draw its molecular structure like H-O-H. These are different ways of representing molecules. Writing formulas from molecular structures means writing the formula of the mole...
- Tue Oct 08, 2019 12:55 am
- Forum: Limiting Reactant Calculations
- Topic: M.11 hw prob
- Replies: 1
- Views: 163
Re: M.11 hw prob
So, the question states that there are two reactions occurring. The first reaction occurs between P4 and O2 to yield P4O6. If enough oxygen is present, the oxygen can react further with this oxide to produce P4O10. First, you need to determine the limiting reactant for the first equation. It states ...
- Mon Oct 07, 2019 11:47 pm
- Forum: Photoelectric Effect
- Topic: Post Module Assessment
- Replies: 1
- Views: 100
Re: Post Module Assessment
The photoelectric experiment led to the rise of the equation: E=hv. This is because the photoelectric effect showed that it isn't the intensity of the light that determines the energy of the individual photons but the frequency of the light since no electrons were removed by long-wavelength or in ot...
- Sun Oct 06, 2019 11:32 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Theoretical vs. Actual Yield
- Replies: 38
- Views: 14093
Re: Theoretical vs. Actual Yield
The theoretical yield is what you would obtain in perfect conditions where the reactants are pure. However, during an experiment, side reactions could occur, the reactants could stick to the walls of the container, decreasing the amount of reactants that are reacting, or impurities in the container ...
- Sun Oct 06, 2019 10:52 pm
- Forum: Limiting Reactant Calculations
- Topic: Reducing reactants
- Replies: 2
- Views: 162
Re: Reducing reactants
If the question does not specify with which compound iron (III) oxide was reduced, I don't think there is any way for you to write a balanced equation as the iron (III) oxide could react with a wide variety of compounds to gain an electron and become reduced. The only thing you could do would be to ...