Search found 100 matches
- Sat Mar 14, 2020 6:50 pm
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 1
- Views: 181
Re: Half Life
I think it has to do with the fact that a first-order reaction's rate scales directly with the concentration (rate = k[A]). If you increase the concentration of the reactant, the rate will also increase by the same scalar. The half life isn't affected by this change because while there would be more...
- Sat Mar 14, 2020 6:44 pm
- Forum: Van't Hoff Equation
- Topic: ln
- Replies: 34
- Views: 1936
Re: ln
eln(x) = x
- Sat Mar 14, 2020 6:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Internal Energy
- Replies: 6
- Views: 587
Re: Internal Energy
The internal energy of an ideal gas is proportional to its mass and temperature (deltaU = 1.5*n*R*deltaT). Both mass and temperature are constant in an isothermal expansion, so the internal energy is constant (deltaU = 0). Internal energy, heat, and work are related by deltaU = q + w. deltaU = 0, so...
- Sat Mar 14, 2020 6:23 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Non spontaneous to spontaneous process?
- Replies: 2
- Views: 315
Re: Non spontaneous to spontaneous process?
Given the above statements are true: deltaG = deltaH - T*deltaS. If deltaS > 0, then T*deltaS is positive. Increasing T means that T*deltaS becomes larger, but it is subtracted. So deltaG would be decreasing as T increases. If your deltaG is positive before you start increasing temperature, then the...
- Sat Mar 14, 2020 6:12 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A- frequency factor
- Replies: 3
- Views: 323
Re: A- frequency factor
A's numerical value is unique for a reaction just like the rate constant k. It also has the same units as the rate constant. A unique first-order reaction has a unique rate constant k and frequency factor A, both with units s -1 (because it is a first-order reaction). k and A are related by the Arrh...
- Sun Mar 08, 2020 3:48 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A in the Arrhenius Equation
- Replies: 8
- Views: 550
Re: A in the Arrhenius Equation
Note that the A constant is a unique value for each chemical reaction, like the k constant.
- Sun Mar 08, 2020 3:44 pm
- Forum: Second Order Reactions
- Topic: Half-life of Second-Order
- Replies: 4
- Views: 506
Re: Half-life of Second-Order
Also need to know: for a zero-order reaction, t1/2=[A0]/2k
- Sun Mar 08, 2020 3:38 pm
- Forum: Zero Order Reactions
- Topic: Not used Half life
- Replies: 8
- Views: 974
Re: Not used Half life
The half-life of a second-order reaction is t1/2=1/k[A0]
- Sun Mar 08, 2020 3:36 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: units
- Replies: 11
- Views: 767
Re: units
Adding on, keep in mind that these units are the same for all rates regardless of order; because of this, the k constant of the reaction will have different units based on the reaction's order.
- Sun Mar 08, 2020 3:34 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: What is 'A'?
- Replies: 5
- Views: 426
Re: What is 'A'?
A is a unique constant for a chemical reaction, similar to the k constant of a reaction.
- Sun Mar 01, 2020 2:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 10
- Views: 503
Re: Salt Bridge
I noticed that some cell diagrams in the homework don't include salt bridges.. when is this possible? If you look at figures 6L2 and 6L3 in the textbook, there are cells in which the two half-reaction solutions have some contact with each other; so some cells have other means of ion transfer than a...
- Sun Mar 01, 2020 2:23 pm
- Forum: First Order Reactions
- Topic: first order
- Replies: 4
- Views: 357
Re: first order
For a first-order reaction, the rate is directly proportional to the concentration (e.g. if the concentration of a reactant was doubled, the rate of the reaction would be doubled.) For a second-order reaction, the rate is proportional to the second power (square) of the concentration (e.g. if the co...
- Sun Mar 01, 2020 2:18 pm
- Forum: General Rate Laws
- Topic: units
- Replies: 9
- Views: 551
Re: units
Units are change in concentration per second (mol x L-1 x s-1). Keep in mind that because of this, the reaction constant k may have different units for different rate laws.
- Sun Mar 01, 2020 2:13 pm
- Forum: General Rate Laws
- Topic: Integrated Rate Law
- Replies: 5
- Views: 381
Re: Integrated Rate Law
Integrated rate laws show reaction rate vs. time. Differential rate laws show rate as a function of the reactant concentration [R].
- Sun Mar 01, 2020 2:10 pm
- Forum: Balancing Redox Reactions
- Topic: 6K3 Help
- Replies: 1
- Views: 133
Re: 6K3 Help
Note that there are two sulfur atoms involved. The oxidation number of each sulfur in the reactants is +2. In the products. each is +6. Each sulfur has an oxidation number increase of +4, so there is a net transfer of eight electrons as shown in the balanced oxidation reaction.
- Sun Feb 23, 2020 2:54 pm
- Forum: Balancing Redox Reactions
- Topic: Alkaline reactions
- Replies: 2
- Views: 195
Re: Alkaline reactions
I believe the main difference is that at after you combine the half-reactions, you neutralize the H+ by adding hydroxide to each side of the equation.
- Sun Feb 23, 2020 2:51 pm
- Forum: Balancing Redox Reactions
- Topic: Figuring Out Electrons Transferred for a Problem Where Both Sides Have The Same Oxidation Number
- Replies: 3
- Views: 229
Re: Figuring Out Electrons Transferred for a Problem Where Both Sides Have The Same Oxidation Number
I think if you balance the half reaction O3 -> O2, you'll get O3 + 2H+ + 2e- = O2 + H2O. Notice that this actually is a reduction reaction since the ozone gains electrons (reactant side). So This would work as a half-reaction even though the oxidation numbers don't change.
- Sun Feb 23, 2020 2:39 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox reactions
- Replies: 4
- Views: 240
Re: Balancing Redox reactions
Adding on, keep in mind you add H2O to balance O regardless of acidic/basic reaction. It's the hydrogen/proton balancing that's different for acidic/basic.
- Sun Feb 23, 2020 2:31 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 5
- Views: 339
Re: salt bridge
The ultimate purpose of the salt bridge is to keep the battery running (so it doesn't run itself to equilibrium quickly). It does so by maintaining charge balance as mentioned above.
- Fri Feb 21, 2020 11:02 am
- Forum: Balancing Redox Reactions
- Topic: Oxidation numbers
- Replies: 6
- Views: 441
Re: Oxidation numbers
Keep in mind that any molecule made of only one element will have oxidation number of 0 if it's neutral charge.
- Sun Feb 16, 2020 6:58 pm
- Forum: Balancing Redox Reactions
- Topic: Reduction vs. oxidation
- Replies: 29
- Views: 1195
Re: Reduction vs. oxidation
In an equation, you can also look at oxidation numbers. Oxidized elements will have an increased oxidation number in the products. Reduced elements will have a decreased oxidation number.
- Sun Feb 16, 2020 6:56 pm
- Forum: Balancing Redox Reactions
- Topic: Identifying Elements Undergoing Oxidation/Reduction
- Replies: 5
- Views: 256
Re: Identifying Elements Undergoing Oxidation/Reduction
Are you ignoring the H+ and H2O in the reactant and product? Do they not matter for this problem? They don't really matter for part a. To find the oxidation number of a single element in a compound, you don't really need to look at the other reactants. But you will definitely need to consider them ...
- Sun Feb 16, 2020 6:50 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibb's Free Energy
- Replies: 7
- Views: 380
Re: Gibb's Free Energy
Gibb's Free Energy is energy available to do work in reaction. It's different from other energy functions (like enthalpy) because it takes energy loss due to entropy into account, since real work is not 100% reversible.
It's mainly used to tell If a reaction is spontaneous.
It's mainly used to tell If a reaction is spontaneous.
- Sun Feb 16, 2020 6:44 pm
- Forum: Balancing Redox Reactions
- Topic: Identifying Elements Undergoing Oxidation/Reduction
- Replies: 5
- Views: 256
Re: Identifying Elements Undergoing Oxidation/Reduction
You can also look at the element's oxidation number before and after the equation. Elements whose oxidation number increases are oxidized, and vice versa for reduced. For 6K1: Given H is typically +1 oxidation and oxygen is typically -2 oxidation number, we can tell that our two elements undergoing ...
- Sun Feb 16, 2020 6:29 pm
- Forum: Balancing Redox Reactions
- Topic: Oxygen
- Replies: 9
- Views: 462
Re: Oxygen
I believe that is correct for almost all compounds. There are some rare exceptions like peroxides and metal hydrides.
- Sun Feb 09, 2020 4:00 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs. extensive, state vs. non state
- Replies: 6
- Views: 262
Re: Intensive vs. extensive, state vs. non state
Not too sure about relation between intensive/extensive and state/nonstate, but state/non-state functions so far have usually in relation to equilibrium and energy processes (enthalpy, specific heat, and Gibbs free energy are all examples of state functions). Intensive/extensive properties are deter...
- Sun Feb 09, 2020 3:54 pm
- Forum: Phase Changes & Related Calculations
- Topic: heat added/released
- Replies: 6
- Views: 332
Re: heat added/released
I think you could find this by determining of the reaction is exothermic or endothermic reactions (endothermic reactions require a heat input). Sometimes you can tell this just by looking at the reaction. Ex. If the rxn is one reactant being broken into several products, it's probably exothermic bec...
- Sun Feb 09, 2020 3:51 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Higher the heat capacity
- Replies: 4
- Views: 135
Re: Higher the heat capacity
Adding on, this is a separate term from heat capacity, which is not measured per gram (The heat capacity of 5 grams of water is different than that of 10 grams of water).
- Sun Feb 09, 2020 3:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: How is heat capacity a state function?
- Replies: 3
- Views: 3828
Re: How is heat capacity a state function?
I thought that if it relies on the change in heat/transfer of heat then it is not a state function? Heat capacity's reliance on heat transfer is consistent (how the heat is added does not change the temperature outcome), so it is a state function. Keep in mind that enthalpy is also a state function...
- Sun Feb 09, 2020 3:38 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter and Bomb Calorimeter
- Replies: 4
- Views: 436
Re: Calorimeter and Bomb Calorimeter
Adding on, because calorimeter's measure temperature changes, they will typically be seen in problems regarding specific heat capacities.
- Sun Feb 02, 2020 12:48 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Phase change
- Replies: 20
- Views: 864
Re: Phase change
Enthalpy will be positive because the molecules must absorb energy to loosen forces on each other and assume more free form.
- Sun Feb 02, 2020 12:46 pm
- Forum: Calculating Work of Expansion
- Topic: graphs of irreversible vs reversible?
- Replies: 2
- Views: 115
Re: graphs of irreversible vs reversible?
An irreversible expansion happens under a constant pressure, while the pressure for a reversible expansion will vary. So the pressure values will show differently on the graphs.
- Sun Feb 02, 2020 12:39 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Combustion Reactions
- Replies: 5
- Views: 223
Re: Combustion Reactions
Does anyone have any good videos explaining combustion reactions?
There's a brief explanation in the textbook section F63.
- Sun Feb 02, 2020 12:30 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Extensive/Intensive Property
- Replies: 4
- Views: 93
Re: Extensive/Intensive Property
what is the difference between extensive and intensive properties? just that they are affected by volumes?
Extensive properties change based on the amount present. Intensive properties do not.
- Sun Feb 02, 2020 12:26 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Boltzmann Equation
- Replies: 1
- Views: 83
Re: Boltzmann Equation
This equation is used to calculate the entropy of an object when we know how many ways the molecules in the system can be arranged without changes in energy. If we know that a molecule can be oriented in X number of ways , we can find the entropy of virtually any amount of that compound using the re...
- Sun Jan 26, 2020 4:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: protonization/ionization
- Replies: 4
- Views: 171
Re: protonization/ionization
If you look at an ICE chart of the reaction, this would be the concentration of the conjugate product at equilibrium over the initial concentration of the acid/base.
- Sun Jan 26, 2020 4:34 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 7
- Views: 400
Re: Heat Capacity
How do we know the heat capacity?
There's a formula for calculating it given heat and temperature (textbook p. 251). For specific heat capacities, those are unique for every substance.
- Sun Jan 26, 2020 4:27 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Properties
- Replies: 4
- Views: 154
Re: State Properties
A state property is determined only by the "start" and "finish" values of a process. Basic example: If I walk 5m forward, then walk backward 2m, I am 3m forward from my original staring point. This displacement would be the same if I simply walked 3m forward; or if I walked 500m ...
- Sun Jan 26, 2020 9:49 am
- Forum: Calculating Work of Expansion
- Topic: Calculating Work
- Replies: 1
- Views: 127
Re: Calculating Work
Pay attention to what the work is in reference to. Say you have a system and surroundings. If positive work is done BY the system, energy in the system is expended. This is equivalent to NEGATIVE work done ON the system. If negative work is done BY the system, energy is put into the system. This is ...
- Sun Jan 26, 2020 9:42 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 7
- Views: 400
Re: Heat Capacity
Substances with higher heat capacity require more energy to raise its temperature and will have to expend more energy to cool down. If you're referring to heat transfer between two substances, the substance with a higher heat capacity will experience a smaller change in temperature because more ener...
- Fri Jan 17, 2020 3:39 pm
- Forum: Ideal Gases
- Topic: ph
- Replies: 10
- Views: 513
Re: ph
when trying to find the pH or poH of something, do We take the - log of the opposite concentration of the one we are trying to find?
No; pH = -log[H+] and pOH=-log[OH-].
But you can use pH to find pOH and vice versa because pH + pOH = 14.
- Fri Jan 17, 2020 3:36 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH
- Replies: 2
- Views: 186
Re: pH
pH is a scale. It's logarithmic, so a linear increase in pH is not a linear increase in [H+].
- Fri Jan 17, 2020 3:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5 percent rule
- Replies: 10
- Views: 534
Re: 5 percent rule
The 5% rule should be considered when you remove x- additions/subtracts to make the ICE equation easier to solve (when K <10^-3)
- Fri Jan 17, 2020 3:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework question 5H.1 PART B
- Replies: 2
- Views: 112
Re: Homework question 5H.1 PART B
The (b) equation is the original equation of the problem scaled by 1/2. If you multiple an entire equation by a scalar (in this case, 1/2), the K constant changes by being raised to that power (in this case, K=41 is raised to the power 1/2 to get K for the part b equation).
- Fri Jan 17, 2020 3:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6B.11 Part b
- Replies: 1
- Views: 44
Re: 6B.11 Part b
Keep in mind that this problem is asking for mass, not concentration. So you don't need the MV formula because you already have the necessary concentration, but concentration x volume = mass. Concentration is independent of volume, so the 18 mol/L for the original 5mL solution applies also to the or...
- Fri Jan 10, 2020 4:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Catalysts
- Replies: 7
- Views: 192
Re: Catalysts
A common example of catalyst is enzymes, proteins that facilitate reactions in biological systems. For example, amylase is an enzyme in saliva that breaks starches from food into digestible sugars at a faster rate. Without enzymes like amylase, it would be much slower gaining energy from consumed fo...
- Fri Jan 10, 2020 3:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: reactants compared to products
- Replies: 4
- Views: 158
Re: reactants compared to products
Whether or not product equilibrium concentration will increase depends on the reaction's K constant. For example, if you start with a higher concentration of reactants and products and the reaction's K value is very high, yes, product will be formed and the product concentration will be increased at...
- Fri Jan 10, 2020 3:52 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: N2+3H2<->2NH3
- Replies: 5
- Views: 152
Re: N2+3H2<->2NH3
When a reaction goes right, it will begin producing more net product. One case that this will happen in this example is when reactant is added (N2 is increased)
- Fri Jan 10, 2020 3:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.23 Final Answer
- Replies: 1
- Views: 67
Re: 5I.23 Final Answer
Some of the intermediate calculations are rounded in the answer book. I don't think the difference is that significant, though.
- Fri Jan 10, 2020 3:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: PCl5 example in lecture
- Replies: 2
- Views: 132
Re: PCl5 example in lecture
The 2X change is correct. Remember, the Xs represent how much product is produced when reactant is consumed, and this is based on the stoichiometric coefficients. The 2x^2 is probably referring to the K constant. From his example, we used the ICE chart's equilibrium values to determine constant K = ...
- Sat Dec 07, 2019 4:21 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma Vs Pi
- Replies: 12
- Views: 813
Re: Sigma Vs Pi
Also know where the bonds form.
A single bond has one sigma bond.
Double bonds have one sigma and one pi bond.
Triple bonds have one sigma and two pi bonds.
A single bond has one sigma bond.
Double bonds have one sigma and one pi bond.
Triple bonds have one sigma and two pi bonds.
- Sat Dec 07, 2019 4:15 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Relationship between pKa, pKb, and acidity strength?
- Replies: 1
- Views: 165
Re: Relationship between pKa, pKb, and acidity strength?
pK = -logK. K is an equilibrium constant (Ka for acids, Kb for bases)
pKw = 14.
pKa + pKb = pKw
Stronger acids have a higher Ka value and a lower pKa value. Same goes for bases and Kb.
pKw = 14.
pKa + pKb = pKw
Stronger acids have a higher Ka value and a lower pKa value. Same goes for bases and Kb.
- Sat Dec 07, 2019 3:54 pm
- Forum: Significant Figures
- Topic: Significant Figures during the Final.
- Replies: 1
- Views: 150
Re: Significant Figures during the Final.
You can just add zeros if you need more sig figs (say, 0.34 to 0.340). Also, as long as it isn't too small, you don't always have to bother with scientific notation (0.045 and 4.5x10^-2 would both likely be acceptable)
- Sat Dec 07, 2019 3:49 pm
- Forum: Hybridization
- Topic: Hybradization
- Replies: 3
- Views: 385
Re: Hybradization
That first 2 refers to the shell n=2: The orbitals in the valence shell are being hybridized (because only the valence electrons are involved in bonding) and the valence shell for carbon is n=2.
I don't think it's 100% necessary (in the textbook it's not used all the time).
I don't think it's 100% necessary (in the textbook it's not used all the time).
- Sat Dec 07, 2019 3:43 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs. Amphoprotic
- Replies: 1
- Views: 279
Re: Amphoteric vs. Amphoprotic
Both terms refer to substances that behave as acids and bases, but amphiprotic substances have hydrogen atoms (they can donate protons). So amphiprotic substances also are amphoteric, but not always vice versa. ex. Aluminum oxide is amphoteric but not amphiprotic, because it can react to both acid a...
- Sun Dec 01, 2019 9:11 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 6
- Views: 408
Re: Coordination Number
Coordination number is how many ligands are directly bonded to the central atom. This is basically everything in the coordination sphere, so coordination number = number of ligands in the bracket. For your example: in the bracket are 4 ligands (Br4) bound to the transition metal. The coordination nu...
- Sun Dec 01, 2019 9:08 am
- Forum: Biological Examples
- Topic: Vitamin B12
- Replies: 3
- Views: 181
Re: Vitamin B12
B12 specifically acts as a coenzyme in the production of said components.
- Sun Dec 01, 2019 8:54 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxidation number
- Replies: 3
- Views: 272
Re: Oxidation number
The sum of oxidation numbers of each component is the complex's overall charge. Anions have oxidation numbers equal to their charges. This includes anion ligands. Neutral ligands have oxidation number 0. Cations with fixed charges (like K[sup]+/sup]) have oxidation numbers equal to their charges. Fr...
- Sun Dec 01, 2019 8:41 am
- Forum: Biological Examples
- Topic: Cisplatin vs Transplatin
- Replies: 2
- Views: 240
Re: Cisplatin vs Transplatin
The cis-chlorine arrangement on cisplatin (the two chlorines are on the same side of the central atom) is what allows it to bind as a ligand to DNA molecules. This interaction interrupts DNA replication, so it can be used to treat cancerous cells. Transplatin does not have this cis-chlorine arrangem...
- Sun Dec 01, 2019 8:27 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Mondentate/Bidentate
- Replies: 1
- Views: 106
Re: Mondentate/Bidentate
I believe water is only monodentate because the available lone pairs are on one atom; even though there are two open lone pairs, the geometry would not favor two attractions to the same atom.
- Sun Nov 24, 2019 8:40 pm
- Forum: Naming
- Topic: Oxidation Numbers
- Replies: 2
- Views: 234
Re: Oxidation Numbers
Oxidation numbers are a measure of the relative number of electrons each atom in a molecule has. I believe it's measured because of how some atoms share electrons in bonds. When all the atomic numbers of the atoms in a molecule are added up, they equal the molecules overall charge. But keep in mind ...
- Sun Nov 24, 2019 8:33 pm
- Forum: Naming
- Topic: Meaning of Cis and Trans
- Replies: 11
- Views: 906
Re: Meaning of Cis and Trans
Adding on:
cis- means something like "on one side", and trans means "across".
cis-molecule are typically polar and trans-molecules are typically nonpolar.
cis- means something like "on one side", and trans means "across".
cis-molecule are typically polar and trans-molecules are typically nonpolar.
- Sat Nov 23, 2019 1:48 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination number
- Replies: 1
- Views: 149
Re: Coordination number
I don't think there is one. You could guess a possible shapes based on the coordination number, but its not reliable like VSEPR is (VSEPR doesn't apply to these complexes)
- Sat Nov 23, 2019 1:39 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentate
- Replies: 4
- Views: 208
Re: Polydentate
Note that polydentate can refer to tridentate, tetradentate, etc (not mono- or bidentates). It depends on how many atoms in the ligand have lone pairs available.
- Sat Nov 23, 2019 1:26 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Sphere
- Replies: 2
- Views: 162
Re: Coordination Sphere
Adding on, note that because the sphere is the central atom and bonded ligands, not all components in a coordinate complex may be in the coordination sphere. That's why in the notation, the components in the coordinate sphere are bracketed.
- Sun Nov 17, 2019 1:17 pm
- Forum: Bond Lengths & Energies
- Topic: Polarizability
- Replies: 4
- Views: 349
Re: Polarizability
Polarizability in anions is how easily the electron cloud of an atom is distorted. It's a greater value for larger anions. For cations, polarizability is low but polarizing power is high (how easily it can attract the electrons from another atom. This value is typically greater for smaller, more pos...
- Sun Nov 17, 2019 1:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion Strength
- Replies: 4
- Views: 264
Re: Repulsion Strength
Repulsion between lone pairs > repulsion between a lone pair and a bonding pair> repulsion between bonding pairs
- Sun Nov 17, 2019 1:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair location
- Replies: 3
- Views: 155
Re: Lone Pair location
In some shapes such as bent, it is physically impossible to have lone pairs on opposite sides of the atom. Keep in mind the tetrahedral geometry of bent molecules. For the t-shape, you'll want to look at the lone pair's angles with the other 3 bonds. In the t-shape position, the lone pairs have high...
- Sun Nov 17, 2019 12:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 6
- Views: 397
Re: VSEPR
Adding on, minimal electrostatic repulsion is achieved when the electron-dense regions (bonds and lone pairs) on an atom are farthest from each other. There is an approximate maximum angle between bonds that can be achieved based on how many bonds are on that atom, and that is the basis of the bond ...
- Thu Nov 14, 2019 2:25 pm
- Forum: Bond Lengths & Energies
- Topic: Dashes and Wedges
- Replies: 4
- Views: 311
Re: Dashes and Wedges
We won't be asked to actually draw the dashes/wedges diagrams.
- Sat Nov 09, 2019 4:21 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: Hydrogen Bonding
- Replies: 4
- Views: 259
Re: Hydrogen Bonding
I think there is a possibility of other electronegative atoms forming hydrogen bonds, but N/O/F are the specific elements for which the hydrogen bonds are favorable and the strongest, so N/O/F hydrogen bonds are the only ones we should be concerned with.
- Thu Nov 07, 2019 3:07 pm
- Forum: Lewis Structures
- Topic: When to draw Resonance Structures
- Replies: 14
- Views: 1007
Re: When to draw Resonance Structures
How do we know when a molecule has resonance? After optimizing formal charges on the Lewis structure, you will typically find resonance if there is an arrangement of single/double bonds (maybe triple, though we haven't seen that in class yet) that can be moved around without affecting the overall d...
- Thu Nov 07, 2019 2:50 pm
- Forum: SI Units, Unit Conversions
- Topic: Kj
- Replies: 6
- Views: 518
Re: Kj
Would you divide or multiply?
Multiply by 1000 when converting from kilojoules to souls.
Divide by 1000 for vice versa.
- Wed Nov 06, 2019 2:00 pm
- Forum: Lewis Structures
- Topic: Ionic Lewis structure
- Replies: 2
- Views: 147
Re: Ionic Lewis structure
We're not being tested on nomenclature, so while it's probably good to know the basic ones (like ionic ones such as magnesium sulfide), there shouldn't be any questions that we can't do if we don't know nomenclature.
- Wed Nov 06, 2019 1:46 pm
- Forum: Properties of Light
- Topic: Speed of Light
- Replies: 7
- Views: 630
Re: Speed of Light
c is given as 3.00 x 108 meters per second (m/s)
- Thu Oct 31, 2019 3:08 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 4
- Views: 199
Re: Formal Charge
What's the formal charge of NaOH?
NaOH is an ionic compound, so you would draw Na+ and OH- structures separately.
Looking at the structures and using the formal charge formula, you would get:
Na would have FC=1, H would have FC=0, and O would have FC=-1.
- Thu Oct 31, 2019 3:00 pm
- Forum: Lewis Structures
- Topic: Valence Electrons from Periodic Table
- Replies: 10
- Views: 686
Re: Valence Electrons from Periodic Table
For example, hw problem 2A.1a asks to give the number of valence electrons (including d electrons) for the element Sb. Since it asked to include d-block, the answer would be 15 valence electrons not 5 electrons correct? The valence electrons for Sb would be 5. Keep in mind that the d-block (4d) tha...
- Thu Oct 31, 2019 2:49 pm
- Forum: Lewis Structures
- Topic: Charges on Lewis Structures
- Replies: 7
- Views: 483
Re: Charges on Lewis Structures
For example is we had Br03- and we were adding up the electrons why would we add one instead of subtract one? A charge of -1 means that the compound has 1 extra electron (more electrons than protons means a negative charge). The Lewis structure would show an amount of electrons equal to the total o...
- Thu Oct 31, 2019 2:39 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge equation
- Replies: 9
- Views: 253
Re: Formal Charge equation
Bond length probably won't work for that. But that form FC=V-(L+B) would work for B = number of bonds that atom has (+1 for singles, +2 for doubles), which is essentially the same thing as S/2. It's actually easier for me personally to do FC = V - (L+B) because I can simply count the number of bonds...
- Thu Oct 31, 2019 2:09 pm
- Forum: Lewis Structures
- Topic: 2B.7
- Replies: 2
- Views: 129
Re: 2B.7
You can use valence electron values to identify E. Count how many electrons are in the Lewis structure. It looks like the structure has 32 electrons based on the four bonds described. You also know the structure has an atom of element E, one oxygen, and three chlorines. You can subtract those atoms'...
- Thu Oct 24, 2019 4:11 pm
- Forum: Trends in The Periodic Table
- Topic: Location of elements
- Replies: 12
- Views: 719
Re: Location of elements
Does anyone know if we should know the elements' chemical symbols too? You'll be given a periodic table on the test, so memorizing all of the elements' symbols is likely not necessary. It's good to know most of the symbols for the more common atoms for efficiency, though. Maybe consciously make not...
- Thu Oct 24, 2019 3:02 pm
- Forum: Properties of Light
- Topic: memorize radiation and its frequencys?
- Replies: 2
- Views: 104
Re: memorize radiation and its frequencys?
You should definitely know the order of types of radiation and an approximate range of frequencies/wavelengths for most of the radiations. I'm now sure if the specific frequencies need to be memorized, but you should probably at least be able to determine that, for example, 400-700nm light is in the...
- Thu Oct 24, 2019 2:34 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: subshell or orbital?
- Replies: 3
- Views: 174
Re: subshell or orbital?
s, p, d, and f are subshells. One p-subshell has three orbitals.
3p is a subshell, but you can also specify a 3p-orbital.
3p is a subshell, but you can also specify a 3p-orbital.
- Thu Oct 24, 2019 2:22 pm
- Forum: Trends in The Periodic Table
- Topic: Periodic Trend Exceptions
- Replies: 7
- Views: 271
Re: Periodic Trend Exceptions
can someone explain to me what trends are? The periodic trends are traits of atoms that change based on the element and can be visualized on the periodic table. For example: atomic radius (basically how big the atoms are). If you put every element's atomic radius on a periodic table, that value wil...
- Thu Oct 24, 2019 2:14 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Energy of spdf orbitals
- Replies: 11
- Views: 399
Re: Energy of spdf orbitals
Can someone explain what a shell is vs a subshell? The shell is the n quantum number (broadest division of electrons in an atom). Shells correspond to the rows in the periodic table. The subshell is the s-p-d-f classification of orbital groups (quantum number l.) Shells are divided into subshells (...
- Thu Oct 17, 2019 4:29 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: (N,l,m)
- Replies: 2
- Views: 135
Re: (N,l,m)
The quantum number m l tells us which orbital an electron is in. For example, if an electron is in an orbital in the 2p subshell: we know that the 2p-subshell (l=1) has 3 orbitals. These orbitals within 2p are denoted as m l =-1,0,1, which is based on the quantum number l. An electron in a 2p subshe...
- Thu Oct 17, 2019 4:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 7
- Views: 393
Re: Nodal Planes
I recommend looking in the textbook pages 37-38 for a visual. You'll notice the nodal planes divide the lobes of the orbitals and that the nodal planes all cross the nucleus.
- Thu Oct 17, 2019 4:12 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 1D.19
- Replies: 2
- Views: 64
Re: 1D.19
The manual just gives the orbitals. You may have been looking at a different solution.
- Thu Oct 17, 2019 11:40 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Magnetic Quantum number [ENDORSED]
- Replies: 4
- Views: 313
Re: Magnetic Quantum number [ENDORSED]
In the 3p subshell, where l=1, does this mean ml=0? Can ml=0?
Yes. The possible magnetic quantum numbers ml for electrons with l=1 (p-orbitals) are -1, 0, 1.
- Thu Oct 17, 2019 11:34 am
- Forum: Photoelectric Effect
- Topic: Calculating the number of photons [ENDORSED]
- Replies: 2
- Views: 922
Re: Calculating the number of photons [ENDORSED]
You can use the equation E=hv, which refers to the energy of a single photon of light. In this problem, you're asked how many photons have a total given amount of energy. You're given the wavelength of the photons, so you can convert to frequency, use E=hv to find the joules per photon (E), and then...
- Thu Oct 10, 2019 8:51 pm
- Forum: Limiting Reactant Calculations
- Topic: Finding Limiting Reactant
- Replies: 3
- Views: 348
Re: Finding Limiting Reactant
The limiting reactant of a chemical reaction is the reactant that is completely consumed to make the product (some amount of the other reactants will be leftover, or in excess). Say you have two given amounts of reactant that undergo a chemical reaction to make products. Using the balanced chemical ...
- Thu Oct 10, 2019 8:45 pm
- Forum: Empirical & Molecular Formulas
- Topic: M.5
- Replies: 2
- Views: 117
Re: M.5
If you're referring to the subtraction to find the leftover reagent, here's my work: Plug 12mol ClO2 into the equation to convert to mol BrF3 to determine how much BrF3 is consumed. According to the equation, 4mol BrF3 is consumed with 12mol ClO2. Subtract the 4mol BrF3 from the given 5mol BrF3 and ...
- Thu Oct 10, 2019 8:27 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Balmer Series
- Replies: 1
- Views: 207
Re: Balmer Series
I believe for the Balmer series, n=2 is the lower quantum level for electrons. It can be the final or initial state (n1 or n2), depending on whether light is being absorbed or emitted; but the wavelengths of spectral lines involved are the same for absorption and emission.
- Thu Oct 10, 2019 5:01 pm
- Forum: Properties of Light
- Topic: HW 1A.11
- Replies: 1
- Views: 117
Re: HW 1A.11
Says in the textbook that, for the equation, the lowest value of n is the same for all lines in one series. For the Balmer series, the number is 2; for the Lyman series, 1. The lower value of n is the lowest energy level of electrons involved in the spectral lines. And because there are significantl...
- Thu Oct 10, 2019 4:45 pm
- Forum: Empirical & Molecular Formulas
- Topic: Homework F9
- Replies: 4
- Views: 172
Re: Homework F9
You can also try thinking of the decimals as fractions to help you decide what to multiply.
The decimals in the ratio for this problem are basically equivalent to thirds, so you would multiply by 3 to eliminate the fraction.
The decimals in the ratio for this problem are basically equivalent to thirds, so you would multiply by 3 to eliminate the fraction.
- Thu Oct 03, 2019 3:49 pm
- Forum: Empirical & Molecular Formulas
- Topic: Law of Conservation of Mass?
- Replies: 4
- Views: 430
Re: Law of Conservation of Mass?
By the law of conservation of mass, total mass of reactants used equals total mass of product formed. The total reactants (A and B) used have a combined mass of 12g, but there are 14g of product formed. Mass is conserved in chemical reactions, so the product should be mass 12g. The given result is n...
- Wed Oct 02, 2019 10:24 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Fundamental G.3 Concentration
- Replies: 2
- Views: 189
Re: Fundamental G.3 Concentration
You can convert micromoles to moles. The 1.44 micromoles of glucose is equal to 1.44x10^-6 moles of glucose. Now the units are more compatible with the molarity. Divide 1.44x10^-6 moles by the given 1.25x10^-3 mol/L measurement and the mole units will cancel out. [1.44x10^-6 moles]/[1.25x10^-3 mol/L...
- Wed Oct 02, 2019 10:18 pm
- Forum: Balancing Chemical Reactions
- Topic: Fundamental H5 D
- Replies: 3
- Views: 176
Re: Fundamental H5 D
You can save balancing S for last, since it appears several times on one half of the equation.
And since S is its own particle on the reactants side, balancing S will be really easy once the Fe and P are balanced out.
And since S is its own particle on the reactants side, balancing S will be really easy once the Fe and P are balanced out.
- Wed Oct 02, 2019 10:14 pm
- Forum: Empirical & Molecular Formulas
- Topic: 5 Homework Problems Due
- Replies: 21
- Views: 924
Re: 5 Homework Problems Due
Does anyone know if the homework is graded on correctness? If the work is partially wrong or if the answer is incorrect, do we receive a lower grade for the homework that week? There's nothing on the syllabus about how strictly the homework's graded, but given we have access to the solutions manual...
- Wed Oct 02, 2019 2:54 pm
- Forum: Balancing Chemical Reactions
- Topic: Question H7a
- Replies: 6
- Views: 320
Re: Question H7a
Hydroxide has -1 charge because of oxidation numbers. O's oxidation number is -2 and H's oxidation number is -1. You can also think of when water ionizes; it splits into a hydrogen ion (acidic) and hydroxide ion (basic). Hydrogen ions have charge +1 and water is neutral charge, so hydroxide has char...