Search found 102 matches
- Wed Mar 11, 2020 12:46 pm
- Forum: General Rate Laws
- Topic: intermediates
- Replies: 12
- Views: 661
Re: intermediates
Yes. Because they are formed and used up they cancel each other out in the overall equation.
- Wed Mar 11, 2020 12:42 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts vs. Intermediates
- Replies: 8
- Views: 814
Re: Catalysts vs. Intermediates
A catalyst exits in the beginning of a set of reactions and also comes out at the end of a set of reaction, so it is used up and then produced. An intermediate is formed and then used up.
- Wed Mar 11, 2020 12:41 pm
- Forum: Second Order Reactions
- Topic: linear graph
- Replies: 7
- Views: 500
Re: linear graph
To see if the slope is positive or negative you take the value of k from the equation.
- Wed Mar 11, 2020 12:38 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: How to determine Q
- Replies: 4
- Views: 330
Re: How to determine Q
When you write out the half reactions and add them to make the complete equation the answer will result in the reaction that you base Q off of.
- Wed Mar 11, 2020 12:34 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration
- Replies: 9
- Views: 518
Re: Concentration
You need to use the NERNST equation album make sure you set up Q as [anode]/[cathode].
- Mon Mar 09, 2020 12:58 am
- Forum: Balancing Redox Reactions
- Topic: oxidation number
- Replies: 10
- Views: 718
Re: oxidation number
You need to take the known charges of the elements in the molecule and then find the different between that and the overall charge of the reaction.
- Mon Mar 09, 2020 12:56 am
- Forum: Balancing Redox Reactions
- Topic: Half rxns
- Replies: 27
- Views: 1325
Re: Half rxns
Balance it the same as you would with acidic but add OH- at the end to cancel out the H+.
- Sun Mar 08, 2020 10:17 pm
- Forum: Balancing Redox Reactions
- Topic: Why do we flip E for oxidation?
- Replies: 13
- Views: 1055
Re: Why do we flip E for oxidation?
You are only supposed to flip E when you are given reduction potentials and you are looking for oxidation potentials. This is almost all the time becase our appendix gives reduction potentials.
- Sun Mar 08, 2020 10:14 pm
- Forum: General Rate Laws
- Topic: Rate limiting step
- Replies: 12
- Views: 760
Re: Rate limiting step
The rate limiting step is the slowest reaction that occurs.
- Sun Mar 08, 2020 10:10 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 8
- Views: 467
Re: Catalysts
Lowering the activation energy and increasing the rate are the main functions of a catalyst. It’s important to note they go into the reaction and come out; in other words, they are not consumed.
- Tue Feb 25, 2020 4:14 pm
- Forum: Balancing Redox Reactions
- Topic: Acids and Bases
- Replies: 4
- Views: 353
Re: Acids and Bases
You need to add H2O to balance the oxygens and H+ to balance the hydrogens. When you add OH- because the solution is basic you must add it to both sides of the reaction to make H2O by combing H+ and OH-.
- Tue Feb 25, 2020 4:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: standard potential of a redox reaction
- Replies: 3
- Views: 263
Re: standard potential of a redox reaction
Because E is intensive it does not rely on the amount products or reactants present, so you would NOT multiply the E value. The only time you alter the E value is when you flip the equation; then you would multiply it my -1.
- Tue Feb 25, 2020 4:05 pm
- Forum: Balancing Redox Reactions
- Topic: Platinum in cell diagram
- Replies: 10
- Views: 687
Re: Platinum in cell diagram
Graphite and gold are some other metals that also work in place of platinum.
- Tue Feb 25, 2020 3:56 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode vs Anode
- Replies: 6
- Views: 419
Re: Cathode vs Anode
The cathode is the one being reduced and the anode is the one being oxidized.
- Tue Feb 25, 2020 3:54 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gas constant R
- Replies: 5
- Views: 312
Re: Gas constant R
Whenever you are deciding which gas constant to use, look at your units and pick the R that will cancel them out.
- Tue Feb 25, 2020 3:05 pm
- Forum: Balancing Redox Reactions
- Topic: Which equation do we flip?
- Replies: 6
- Views: 371
Re: Which equation do we flip?
If it is a spontaneous galvanic cell, flip whichever equation will give you a positive Ecell. If they say it is non spontaneous, or the batter is dead, make the Ecell negative.
- Tue Feb 25, 2020 3:01 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Spontaneity
- Replies: 8
- Views: 472
Re: Spontaneity
Yes, Delta G = -nFEcell so if Ecell is positive Delta G must be negative and therefore spontaneous. Also keep in mind a negative delta G and positive Ecell means that the battery is working well.
- Tue Feb 25, 2020 2:47 pm
- Forum: Balancing Redox Reactions
- Topic: Flipping Reactions
- Replies: 4
- Views: 269
Re: Flipping Reactions
If it is a battery you want the Ecell to be positive so flip whichever reaction will give you a positive Ecell value.
- Tue Feb 25, 2020 2:43 pm
- Forum: Balancing Redox Reactions
- Topic: half reaction
- Replies: 10
- Views: 615
Re: half reaction
Use H2O to balance the Oxygen in the reaction and then use H+ to balance the Hydrogen as a result of adding H2O. Then balance the charges by adding e-. Multiply the half reactions so that the charges cancel each other out then add the reactions together. If it is a basic solution add OH- to both sid...
- Tue Feb 25, 2020 2:40 pm
- Forum: Balancing Redox Reactions
- Topic: Acid and Bases in Redox Reaction
- Replies: 4
- Views: 367
Re: Acid and Bases in Redox Reaction
You add H+ to the half reactions to balance the hydrogens on either side. You add OH- to both sides to the entire creation to get rid of H+ and turn it into H2O when you are balancing in basic solution.
- Tue Feb 25, 2020 2:37 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 7
- Views: 411
Re: Balancing Redox Reactions
Only cancel the H+ with OH- when it says to balance the equation in basic solution.
- Fri Feb 21, 2020 1:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrode
- Replies: 4
- Views: 282
Re: Electrode
The Pt electrode simply acts as an inert conductor to facilitate e- transfer.
- Fri Feb 21, 2020 1:44 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: E
- Replies: 5
- Views: 309
Re: E
If the reaction spontaneous E is positive because deltaG is negative.
- Fri Feb 21, 2020 1:39 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Potential Difference
- Replies: 2
- Views: 154
Re: Potential Difference
Potential difference = work/charge. From this you can derive Wmax=deltaG=-nFE which can tell you if the reaction is favorable or not.
- Fri Feb 21, 2020 1:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: E v E(standard)
- Replies: 4
- Views: 281
Re: E v E(standard)
E standard is the E only under standard conditions.
- Sun Feb 16, 2020 10:19 pm
- Forum: Balancing Redox Reactions
- Topic: easier to split?
- Replies: 6
- Views: 407
Re: easier to split?
The splitting of the redox reaction into two half reactions makes it easier to balance the reaction by adding electrons and therefore adding h+ to the opposite side.
- Tue Feb 11, 2020 4:22 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: State of matter affect entropy
- Replies: 3
- Views: 248
Re: State of matter affect entropy
Typically entropy will increase as heat is added and vice-versa because deltaS= delta q/T
- Tue Feb 11, 2020 4:18 pm
- Forum: Ideal Gases
- Topic: reversing reactions
- Replies: 83
- Views: 4719
Re: reversing reactions
K reverse : 1/k
K*n : K^n
K*m: K^(1/m)
K*n : K^n
K*m: K^(1/m)
- Tue Feb 11, 2020 4:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Partial Pressure equilibrium problems
- Replies: 2
- Views: 182
Re: Partial Pressure equilibrium problems
Many times you will need to use PV=nRt to find the partial pressures of all the gases, then use an ICE table just like you would with contractions and a Kp value.
- Tue Feb 11, 2020 4:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 20
- Views: 1017
Re: Adding Inert Gas
Adding an inert gas increases the pressure of the system but will not affect the equilibrium constant K or Q because these gases do not react easily because they have a full octet
- Tue Feb 11, 2020 4:03 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pizza Rolls Question 5!! Help
- Replies: 3
- Views: 250
Re: Pizza Rolls Question 5!! Help
No it shouldn't matter because the volume is no longer changing. You can think of it as doing the volume change with constant temperature then the temperature change with the constant final volume.
- Sun Feb 02, 2020 10:04 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: accuracy of bond enthalpies
- Replies: 8
- Views: 339
Re: accuracy of bond enthalpies
The bond enthalpy method is the least accurate because all the bond enthalpy es are averages of many molecules.
- Sun Feb 02, 2020 9:54 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: boltzmann equation
- Replies: 4
- Views: 226
Re: boltzmann equation
Yes. I’m pretty sure W is number of states^number of particles.
- Sun Feb 02, 2020 9:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: Relevance of Phase Changes
- Replies: 9
- Views: 414
Re: Relevance of Phase Changes
When calculating the enthalpy change you need to add the enthalpy as a result of change in temperature as well as the enthalpy that comes from a phase change.
- Sun Feb 02, 2020 9:36 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 7
- Views: 348
Re: Enthalpy
q=enthalpy only when the pressure is constant because no other work is being done.
- Sun Feb 02, 2020 9:33 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess’ Law
- Replies: 10
- Views: 557
Re: Hess’ Law
Hess’ Law is essentially the definition of a state function for enthalpy.
- Sun Jan 26, 2020 11:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid and Base Concentration
- Replies: 3
- Views: 116
Re: Acid and Base Concentration
If you had the concentration of an acid or base you would need to find the [H3O+] or [OH-] then find the PH of the acid. If the PH or POH are very very low they are most likely strong acids/bases.
- Sun Jan 26, 2020 11:23 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Kw Equations
- Replies: 10
- Views: 460
Re: Kw Equations
ka*kb=kw=10^-14
pka+pka=pkw=14 (you get this by taking the -log of the first equation)
Also, these equations are on the equation sheet just replace [H3O+] with ka, [OH-] with kb, pH with pka, and POH with pkb.
pka+pka=pkw=14 (you get this by taking the -log of the first equation)
Also, these equations are on the equation sheet just replace [H3O+] with ka, [OH-] with kb, pH with pka, and POH with pkb.
- Sun Jan 26, 2020 11:17 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka and Kb
- Replies: 10
- Views: 464
Re: Ka and Kb
All acids/bases have a Ka or a Kb but strong acids and bases have such large Ka and Kb's that they are considered to fully dissociate.
- Sun Jan 26, 2020 11:11 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Shifts Left or Right
- Replies: 15
- Views: 501
Re: Reaction Shifts Left or Right
Whenever you see heat added or released from a system, you can treat it just like the concentrations of products and reactants using Le Chatelier's.
- Sun Jan 26, 2020 11:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE
- Replies: 20
- Views: 815
Re: ICE
You may also need to use an ICE table when asked for the PH. Indirectly they are asking for the [H3O+] concentration to find the PH.
- Sun Jan 26, 2020 11:03 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: delta s
- Replies: 5
- Views: 214
Re: delta s
No delta S is entropy which measures change in disorder of a system. Delta H is enthalpy which measures change of heat in a system.
- Sun Jan 26, 2020 11:01 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase changes
- Replies: 8
- Views: 164
Re: Phase changes
Phase changes take up a large amount of heat so although heat is being supplied, the temperature does not change until the threshold for the new phase is reached.
- Sun Jan 26, 2020 10:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Hess's Law
- Replies: 8
- Views: 161
Re: Hess's Law
Hess' Law essential proves that enthalpy is a state function because you are allowed to add enthalpies without any regard for how the value was obtained.
- Sun Jan 26, 2020 10:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Percent Ionization
- Replies: 12
- Views: 491
Re: Percent Ionization
Percent ionization is the x, or [H3O+] concentration divided, by by the initial acid concentration.
- Sun Jan 26, 2020 10:56 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy of Vaporization and Fusion
- Replies: 5
- Views: 130
Re: Enthalpy of Vaporization and Fusion
The energy required to turn a liquid into a gas is a lot more than the energy that is required to turn a solid into a liquid.
- Fri Jan 10, 2020 11:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure's Effect on Equilibrium
- Replies: 6
- Views: 222
Re: Pressure's Effect on Equilibrium
When an inert gas is added, the concentrations of the products and the reactions are the same because there are the same moles present in the same volume container; therefore, K does not change.
- Fri Jan 10, 2020 11:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Table Ratios
- Replies: 7
- Views: 212
Re: ICE Table Ratios
The ratio does not matter, but using whole number coefficients goes along better with the balanced equation.
- Fri Jan 10, 2020 10:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Meaning of equilibrium constant
- Replies: 5
- Views: 203
Re: Meaning of equilibrium constant
When 10^-3<K<10^3, neither the products nor the reactants are significantly favored. However, if K< 1, the reactants are slightly favored and the reaction lies to the left. Also, if K> 1, the products are slightly favored and the reaction lies to the right.
- Fri Jan 10, 2020 10:51 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: K vs Q
- Replies: 9
- Views: 1558
Re: K vs Q
When Q is less than K there are more reactants because a larger denominator in [products]/[reactants] will lead to a smaller value Q. Therefore, this reaction will shift to the right to regain equilibrium. When Q is greater than K there are more products because a larger numerator in [products]/[rea...
- Fri Jan 10, 2020 10:42 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: predicting effects
- Replies: 9
- Views: 386
Re: predicting effects
Removing SO3 will lead to increase in not only NO but also SO3 because when the products are removed the reactants are favored, which means the reaction must shift to the left to once again reach equilibrium to accommodate for the higher concentration of the reactants.
- Mon Dec 09, 2019 3:50 am
- Forum: Bronsted Acids & Bases
- Topic: Strong Acids and Bases
- Replies: 8
- Views: 510
Re: Strong Acids and Bases
Strong acids are HCl, Her, HI, H2SO4, HClO3, HClO4, and HNo3.
The strong bases are group 1 and 2 oxides and hydroxides.
The strong bases are group 1 and 2 oxides and hydroxides.
- Mon Dec 09, 2019 3:47 am
- Forum: Quantum Numbers and The H-Atom
- Topic: n, l ,ml, ms
- Replies: 13
- Views: 1402
Re: n, l ,ml, ms
ms tells you if the electron is spin up or spin down. If it is the first time filling the orbital it is spin up. If you need to pair an electron it will be spin down.
- Mon Dec 09, 2019 3:45 am
- Forum: DeBroglie Equation
- Topic: converting from nm to m
- Replies: 3
- Views: 362
Re: converting from nm to m
You should convert nm to m so that the units cancel with the m in J.
- Mon Dec 09, 2019 3:44 am
- Forum: Lewis Acids & Bases
- Topic: Lewis acid
- Replies: 3
- Views: 341
Re: Lewis acid
NH4+ cannot accept anymore electrons because its octet is full.
- Mon Dec 09, 2019 3:42 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Stronger acid?
- Replies: 13
- Views: 1116
Re: Stronger acid?
HClO2 is the stronger acid because it pulls electrons away from the H-C bonds making them easier to break which results in more H+ ions in solution.
- Mon Dec 09, 2019 3:41 am
- Forum: Calculating the pH of Salt Solutions
- Topic: OH- and H+
- Replies: 6
- Views: 522
Re: OH- and H+
If there is an acid in solution it will result in H+(H3O+) and if there is a base in solution it will result in OH-.
- Mon Dec 09, 2019 3:39 am
- Forum: Calculating the pH of Salt Solutions
- Topic: pH
- Replies: 6
- Views: 311
Re: pH
The higher the H3)+ concentration the lower the pH and the higher the pOH. The higher the OH- concentration the higher the pH and the lower the pOH.
- Mon Dec 09, 2019 3:36 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 2750
Re: Bent Shape
A bent shape can have either 1 or 2 lone pairs.
Re: "Ferrate"
In this case it would be ferrate because the coordination compound has a negative charge.
- Mon Dec 09, 2019 3:32 am
- Forum: Biological Examples
- Topic: Myoglobin
- Replies: 4
- Views: 359
Re: Myoglobin
Myoglobin has the biological capacity to transport 1 single Oxygen molecule.
Re: Oxidation
To find the oxidation, take the charge of the one of the atoms you know for sure. O is always -2 and H is always +1. Essentially, take what you know and find the charges of the other atoms by adding or subtracting it to the charge of the molecule.
- Wed Nov 27, 2019 12:08 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: How do you know is an acid is strong or weak?
- Replies: 6
- Views: 315
Re: How do you know is an acid is strong or weak?
The stronger the acid the more it will dissociate in water. The weaker the acid the less it will dissociate in water
- Wed Nov 27, 2019 12:02 am
- Forum: Naming
- Topic: Alphabetical Order
- Replies: 6
- Views: 367
Re: Alphabetical Order
Do all the ligands in alphabetical order not paying attention to the greek prefixes then put the central metal atom. All of these must be in the coordination sphere. Following the items within the coordination sphere, put the other ions and molecules.
- Tue Nov 26, 2019 11:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity and dipole moments
- Replies: 8
- Views: 569
Re: Polarity and dipole moments
A dipole cancels when a molecule has no lone pairs and the same attachments. It also will cancel when the net dipole moments cancel when they are facing the opposite directions. In addition, it is important to know that 2-3 linear geometry and square planar are non-polar when they have the same atta...
- Tue Nov 26, 2019 11:54 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric
- Replies: 8
- Views: 346
Re: Amphoteric
If you look at Be, Al, Ga, Sn, Pb, and Sb they form a rough diagonal line on the periodic table
- Sun Nov 24, 2019 9:34 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Numbers
- Replies: 4
- Views: 295
Re: Coordination Numbers
The coordination number is the amount of atoms or molecules attached directly to the central atom.
- Sun Nov 24, 2019 9:26 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Transition Metals
- Replies: 7
- Views: 434
Re: Transition Metals
Because the transition metals are all good Lewis acids, they can all form coordination compounds, but I'm pretty sure he said we only need to concern ourselves with the first row.
- Sun Nov 24, 2019 9:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Sphere
- Replies: 5
- Views: 376
Re: Coordination Sphere
The coordination sphere is the sphere around the molecules and ions attached to the transition metal atom. The ligands need to be in the sphere because ligands are the ions attached to the transition metals. Anything within the "[]" is inside the coordination sphere
- Sun Nov 24, 2019 9:12 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: H3O+
- Replies: 12
- Views: 25931
Re: H3O+
H3O+ is has an electron arrangement tetrahedral because there are 4 regions of electron density. However, the shape of H3O+ is trigonal planar because there are 3 bonds and 1 lone pair in H3O+. Be sure when looking at a molecule that you differentiate whether or not you are looking for shape or elec...
- Sun Nov 24, 2019 9:09 pm
- Forum: Sigma & Pi Bonds
- Topic: sigma and pi bonds
- Replies: 27
- Views: 1553
Re: sigma and pi bonds
Yes. All single bonds are sigma bonds. As you add an extra bond, you add a single pi bond to the sigma bond, so a double bond is sigma and pi and a triple bond is a sigma with 2 pis.
- Thu Nov 14, 2019 3:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VESPR Model of H2O
- Replies: 12
- Views: 774
Re: VESPR Model of H2O
H20 has a bent shape because it has 2 lone pairs and 2 single bonds. When trying to determine shape, count all the bonding regions and lone pairs. I assume we will learn about this in class on Friday.
- Thu Nov 14, 2019 3:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape Name
- Replies: 17
- Views: 791
Re: Molecular Shape Name
Yes, you should know the shape names as well as the bonding angles. These are easiest to memorize when you look at them in terms of total bonding regions as opposed to individually. You do not need to know how to draw the structure in 3d space, only the lewis structures; 3d will be reserved for orga...
- Thu Nov 14, 2019 3:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Methane VSEPR
- Replies: 7
- Views: 369
Re: Methane VSEPR
In 3-d Space when all the H atoms are equally spaced from C and when all the H atoms are as far apart as possible, the angle of the H-C-H bonds are approximately 109.5 degrees.
- Thu Nov 14, 2019 3:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Electrons
- Replies: 9
- Views: 426
Re: Electrons
When electrons are close together, their negative charges repel each other which leads to a more unstable molecule. When the electrons are father apart, the electron electron repulsion is much less and in some cases 0.
- Thu Nov 14, 2019 3:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Resonance VSEPR
- Replies: 6
- Views: 226
Re: Resonance VSEPR
When trying to determine shape, only pay attention to bonding regions, not the amount of bonds.
- Fri Nov 01, 2019 12:44 pm
- Forum: Lewis Structures
- Topic: Charges on Lewis Structures
- Replies: 7
- Views: 432
Re: Charges on Lewis Structures
For a molecule with a +1 charge such as ammonium, NH4+, you would subtract one e- from the valence e- so the total valence e- would 8. For a molecule with a -1 share like sulfate, SO4^2-, you would add 2 extra valence e-. The result is 32. To draw the lewis structure, just be sure to satisfy the amo...
- Fri Nov 01, 2019 12:35 pm
- Forum: Lewis Structures
- Topic: Lone Pairs
- Replies: 10
- Views: 397
Re: Lone Pairs
Lone pairs are pairs of electrons that are not shared with other elements. They are represented by dots around an element. To find the amount of lone pairs, count the number of dots and divide that number by 2.
- Fri Nov 01, 2019 12:29 pm
- Forum: Bond Lengths & Energies
- Topic: Single bond vs double bond
- Replies: 14
- Views: 785
Re: Single bond vs double bond
The double bonds are shorter than the single bonds because the extra e- creates more attractions between 2 elements. However, for benzene there are not true single or double bonds. Benzene actually has delocalized bonds, so rather than drawing a hexagon with alternating double bonds, the actually st...
- Fri Nov 01, 2019 12:17 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing electron configuration
- Replies: 7
- Views: 318
Re: Writing electron configuration
Yes, for Ca the electron configuration would en with 4s^2. For Ca^2+, the electron configuration would end with 3p^6.
- Fri Nov 01, 2019 12:12 pm
- Forum: Bond Lengths & Energies
- Topic: bond lengths
- Replies: 10
- Views: 518
Re: bond lengths
Bond dissociation is the energy required to break a chemical bond. For example, to break an H--H bond, the bond dissociation energy is 436D.
- Fri Nov 01, 2019 12:04 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing electron configuration
- Replies: 7
- Views: 318
Re: Writing electron configuration
Whenever you are writing an electron configuration the orbital with the lower n should come first.
- Sun Oct 27, 2019 7:32 pm
- Forum: Lewis Structures
- Topic: Lewis Structure
- Replies: 5
- Views: 164
Re: Lewis Structure
The 2 double bonds on the sulfate atom bring the formal charge of sulfate to 0. It is more important to have a lower formal charge on the central atom because it has a lower electron affinity.
- Sun Oct 27, 2019 7:30 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: p-orbitals
- Replies: 11
- Views: 379
Re: p-orbitals
The Px, Py, Pz should only be used when showing if the orbitals are full.
- Sun Oct 27, 2019 7:25 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 5
- Views: 311
Re: Formal Charge
A single bond is counted as one electron although a single bond has a value of 2 electrons because 1 electron goes to one atom and the other electron goes to the other atom.
- Sun Oct 27, 2019 6:49 pm
- Forum: Properties of Electrons
- Topic: Electron removal
- Replies: 11
- Views: 369
Re: Electron removal
The electrons closer to the nucleus experience a stronger attraction and shield the outer electrons from receiving the same type of attraction.
- Sun Oct 27, 2019 6:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 16
- Views: 641
Re: Valence Electrons
The valence electrons are electrons in the outer shell. If n=3, all of the electrons in that shell are the valance electrons.
- Sun Oct 20, 2019 9:58 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Pauli Exclusion Prinicple
- Replies: 3
- Views: 172
Re: Pauli Exclusion Prinicple
The Pauli Exclusion Principle essentially means that there cannot be more than 1 quantum number per election because, even if they share the same subshell, they will have different spin. If more than 2 electrons were to exist in an orbital they would have the same quantum numbers.
- Sun Oct 20, 2019 9:53 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron configurations of ions
- Replies: 4
- Views: 146
Re: Electron configurations of ions
If the ion is positive, electrons must be taken away from the electron configuration because electrons have a negative charge. When the ion is negative, electrons must be added to the next available subshells.
- Sun Oct 20, 2019 9:49 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Number
- Replies: 4
- Views: 173
Re: Quantum Number
You should not have to memorize anything since it can all be found on the periodic table.
- Sun Oct 20, 2019 9:48 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Ground State
- Replies: 5
- Views: 220
Re: Ground State
Ground state means that all the electrons are in the lowest possible energy levels. An excited state is when the electrons exist in a higher energy level.
- Sun Oct 20, 2019 9:41 pm
- Forum: Properties of Electrons
- Topic: Electron Configuration
- Replies: 4
- Views: 2121
Re: Electron Configuration
The 3d orbital has less energy than the 4s orbital so it must come before because electron configurations are written in order based on amounts of energy.
- Sun Oct 13, 2019 5:53 pm
- Forum: DeBroglie Equation
- Topic: Wavelength
- Replies: 6
- Views: 214
Re: Wavelength
The smallest detectable wavelength is a gamma ray at 10^-14 meters. Professor Lavelle said anything smaller than 10^-15 meters is irrelevant and we should consider it to have an undetectable wavelength.
- Sun Oct 13, 2019 5:34 pm
- Forum: SI Units, Unit Conversions
- Topic: Unit conversion
- Replies: 15
- Views: 1456
Re: Unit conversion
You need to use stoichiometry. (Unit A)(Unit B/Unit A). This will work for any unit so long as they are similar. For example: meters with millimeters or grams with kilograms.
- Sun Oct 13, 2019 5:21 pm
- Forum: Balancing Chemical Reactions
- Topic: Combustion
- Replies: 17
- Views: 905
Re: Combustion
Combustion, or burning, occurs whenever a hydrocarbon interacts with Oxygen. The products are Carbon dioxide and Water. The more oxygen present the more successful the combustion will be.
- Sun Oct 13, 2019 5:15 pm
- Forum: Significant Figures
- Topic: When to apply Sig Figs
- Replies: 6
- Views: 332
Re: When to apply Sig Figs
You should apply sig figs at the end of the calculation so that you do not get a rounding error for your final answer. It will be more accurate if you wait until the end.
- Sun Oct 13, 2019 5:11 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Configuration
- Replies: 5
- Views: 230
Re: Electron Configuration
You need to memorize it based on where the element shows up on the periodic table. The first S orbital begins with 1. The first P orbital starts with 2. The first D orbital starts with 3. The first F orbital starts with 4. For each row you go down on the periodic table these numbers increase by 1.
- Fri Oct 04, 2019 1:19 am
- Forum: Limiting Reactant Calculations
- Topic: Percent or theoretical yield
- Replies: 14
- Views: 1237
Re: Percent or theoretical yield
The theoretical yield is calculated using stoichiometry to find the ideal mass of a product under ideal lab conditions. The percent yield shows how accurate the actual yield is in comparison to the theoretical yield. The percent yield is calculated using the following equation: percent yield= (actua...
- Fri Oct 04, 2019 1:03 am
- Forum: SI Units, Unit Conversions
- Topic: scientific notation
- Replies: 7
- Views: 274
Re: scientific notation
Scientific notation should be used to provide a more simplified view of an extreme number. .000006 is difficult to understand quickly so 6.0 x 10^-6 is used so that scientists can understand the number and it’s ramifications more easily.
- Fri Oct 04, 2019 12:37 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Converting Before or After?
- Replies: 10
- Views: 539
Re: Converting Before or After?
You can have the final units in whichever unit makes the most sense. For example, you would not want a final mass to be 9.8 x 10^-2 kg because you could just say 98g unless it explicitly asks for kg. As you work the problem, you should use whichever units are easiest to use. Grams are usually easies...