Search found 105 matches

by Letty Liu 2C
Fri Mar 13, 2020 7:33 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7.9
Replies: 1
Views: 10

7.9

Can someone explain this problem? The solutions manual mentions different scenarios and I don't really understand it.
by Letty Liu 2C
Tue Mar 10, 2020 11:45 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 7E.1
Replies: 3
Views: 21

7E.1

How does a catalyst affect (a) the rate of the reverse reaction; (b) the value of delta H for the reaction?

Does the catalyst slow the rate of the reverse reaction and have no change on delta H?
by Letty Liu 2C
Tue Mar 10, 2020 11:28 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 7D.7
Replies: 3
Views: 23

7D.7

For the reversible, one-step reaction A + A -> B + C, the forward rate constant for the formation of B is 265 L?mol2 1?min2 1 and the rate constant for the reverse reaction is 392 L mol2 1? min2 1. The activation energy for the forward reaction is 39.7 kJ?mol2 1 and that of the reverse reaction is 2...
by Letty Liu 2C
Tue Mar 10, 2020 11:21 pm
Forum: General Rate Laws
Topic: Different Types of Rate Laws
Replies: 2
Views: 28

Different Types of Rate Laws

What's the difference between differential and integrated rate laws? When do we have 2k as a constant instead of just k?
by Letty Liu 2C
Tue Mar 10, 2020 9:12 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7C.3
Replies: 2
Views: 21

7C.3

Write the overall reaction for the mechanism proposed below and identify any reaction intermediates.
Step1 AC + B -> AB + C Step2 AC + AB -> A2B + C

How do we approach these questions?
by Letty Liu 2C
Tue Mar 10, 2020 7:45 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7C.1
Replies: 1
Views: 17

7C.1

Each of the following is an elementary reaction. Write its rate law and state its molecularity. (a) NO + NO -> N2O2; (b) Cl2 -> Cl + Cl.

Is part a k[NO]^2 and bimolecular? What is part b?
by Letty Liu 2C
Sat Mar 07, 2020 5:53 pm
Forum: General Rate Laws
Topic: 7A.17
Replies: 5
Views: 53

7A.17

For part a, we're asked to write the rate law of the reaction. I understand the general way to determine the reaction orders, but how would we know to compare experiments 2 and 3 for reactant B? Why couldn't we compare experiments 1 and 3 instead?
by Letty Liu 2C
Tue Mar 03, 2020 5:07 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6.53
Replies: 2
Views: 33

Re: 6.53

Yes, since the lower concentration cell is usually the product and at the anode (the oxidation), this leaves the higher concentration cell in the reduced half of the reaction.
by Letty Liu 2C
Tue Mar 03, 2020 5:04 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 3
Views: 40

Re: Nernst Equation

I think it depends on what information you're given, so what you're working with. I believe there is only two versions of the Nernst equation though: one with lnQ and one with logQ.
by Letty Liu 2C
Mon Mar 02, 2020 4:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6.53
Replies: 1
Views: 24

6.53

"How will each of the following changes affect the cell potential? Justify your answers. (b) Adding 100 mL pure water to the anode compartment. (c) Adding 100 mL of 1.0 m NaOH(aq) to the cathode compartment (Cr(OH)3 is insoluble). (d) Increasing the mass of the chromium electrode in the anode c...
by Letty Liu 2C
Mon Mar 02, 2020 4:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6.51
Replies: 1
Views: 24

6.51

This is the question: "A galvanic cell functions only when the electrical circuit is complete. In the external circuit the current is carried by the flow of electrons through a metal wire. Explain how the current is carried through the cell itself." Does the salt bridge help carry the curr...
by Letty Liu 2C
Mon Mar 02, 2020 4:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Deciding Where Reactions Occur
Replies: 2
Views: 26

Deciding Where Reactions Occur

Does the reduction retain always occur at the electrodes with higher concentration? Is this because the reduction reaction is like the "reactants" of the redox reaction?
by Letty Liu 2C
Sun Mar 01, 2020 1:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.13
Replies: 2
Views: 23

6M.13

Identify the reactions with K . 1 in the following list and, for each such reaction, identify the oxidizing agent and calculate standard cell potential. For part b, shouldn't the SRP for Ce3+ -> Ce 4+ be -1.61 since it's the reversed reaction of Ce4+ -> Ce3+? Do we just ignore the equation we're giv...
by Letty Liu 2C
Sun Mar 01, 2020 2:00 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potential
Replies: 3
Views: 13

Standard Cell Potential

Do standard cell potentials always have to be positive? Also, is it just the cell potential of the reduction reaction minus the oxidation reaction?
by Letty Liu 2C
Tue Feb 25, 2020 5:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 4
Views: 74

6M.5

For each reaction that is spontaneous under standard con- ditions (that is, K . 1), write a cell diagram, determine the stan- dard cell potential, and calculate DG8 for the reaction: (a) 2NO32(aq)18H1(aq)16Hg(l)S 3 Hg221(aq) 1 2 NO(g) 1 4 H2O(l) (b) 2 Hg21(aq) 1 2 Br2(aq) S Hg221(aq) 1 Br2(l) (c) Cr...
by Letty Liu 2C
Tue Feb 25, 2020 4:57 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Calculating Standard Potentials
Replies: 4
Views: 49

Calculating Standard Potentials

When calculating standard potentials for electrodes and two redox reactions, do we just subtract the right from the left for electrodes but use standard Gibbs free energy for two redox reactions?
by Letty Liu 2C
Mon Feb 24, 2020 10:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potential
Replies: 2
Views: 49

Standard Cell Potential

Why can we not just add the standard potentials of the redox reactions? Like in example 6M.2, why do they not use the same method as in 6M.1.
by Letty Liu 2C
Mon Feb 24, 2020 3:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 D
Replies: 1
Views: 21

6L.5 D

For part D, I separated the two half reactions as Au+(aq) -> Au (s) and then Au+(aq) -> Au3+(aq). Is this right? I end up with a different Au in my cell reaction than the answer.
by Letty Liu 2C
Tue Feb 18, 2020 10:58 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 7
Views: 45

Oxidation Numbers

When calculating net charges, are oxygen and hydrogen the only atoms that will always be its actual oxidation number?
by Letty Liu 2C
Tue Feb 18, 2020 10:53 pm
Forum: Balancing Redox Reactions
Topic: Acidic vs. Basic
Replies: 1
Views: 18

Acidic vs. Basic

Is the only difference between acidic and basic solutions the H/OH? I'm not sure if this is right: for acidic solutions, we just add hydrogen ions where necessary but for basic solutions, we add water molecules on both sides before adding hydroxide.
by Letty Liu 2C
Tue Feb 18, 2020 10:51 pm
Forum: Balancing Redox Reactions
Topic: 6K.1
Replies: 1
Views: 33

6K.1

The following redox reaction is used in acidic solution in the Breathalyzer test to determine the level of alcohol in blood: H1 (aq) 1 Cr2O722 (aq) 1 C2H5OH(aq) ¡ Cr31 (aq) 1 C2H4O(aq) 1 H2O(l) Identify the elements undergoing oxidation or reduction and indicate their initial and final oxidation num...
by Letty Liu 2C
Tue Feb 18, 2020 5:08 pm
Forum: Van't Hoff Equation
Topic: 5.55
Replies: 2
Views: 19

5.55

C(s) 1 H2O(g) ∆CO(g) 1 H2(g). (a) Evaluate K At 900 K, given that the standard Gibbs free energies of formation of CO(g) and H2O(g) at 900 K are 2191.28 kJ?mol21 and 2198.08 kJ?mol21, respectively. (b) A sample of graphite of mass 5.20 kg and 125 g of water were placed into a 10.0-L container and he...
by Letty Liu 2C
Tue Feb 18, 2020 5:04 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5J.15
Replies: 2
Views: 45

5J.15

Calculate the equilibrium constant at 25 8C and at 150 8C for each of the following reactions, using data available in Appendix 2A:
(a) NH4Cl(s) ∆ NH3(g) 1 HCl(g)
(b) H2(g) 1 D2O(l) ∆ D2(g) 1 H2O(l)

For part b, why does the solutions manual leave out the gaseous compounds in the enthalpy equation?
by Letty Liu 2C
Wed Feb 12, 2020 12:00 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Adiabatic
Replies: 2
Views: 34

Adiabatic

When a system is adiabatic, what do we assume about delta U, w, and q?
by Letty Liu 2C
Tue Feb 11, 2020 11:57 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Cp and Cv
Replies: 2
Views: 35

Cp and Cv

How do we know when to use the ideal gas 3/2R, 5/2R, etc. ratios for Cp/Cv?
by Letty Liu 2C
Tue Feb 11, 2020 11:55 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: change in enthalpy
Replies: 2
Views: 56

change in enthalpy

Why does the change in enthalpy equation for constant volume use Cp in its nCpT equation?
by Letty Liu 2C
Tue Feb 11, 2020 11:51 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G
Replies: 2
Views: 45

delta G

How do we know if delta G = 0 if we're just given molecules? Are diatomic molecules the only ones that are at equilibrium?
by Letty Liu 2C
Tue Feb 11, 2020 11:50 pm
Forum: Calculating Work of Expansion
Topic: Midterm Q
Replies: 1
Views: 41

Midterm Q

Do we need to know isobaric or isochoric processes for the midterm?
by Letty Liu 2C
Sat Feb 08, 2020 6:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 3
Views: 22

Bond Enthalpies

How do we know which bonds are broken/formed when given a reaction? Do we have to draw out the lewis structures?
by Letty Liu 2C
Sat Feb 08, 2020 6:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Vaporization and Condensation
Replies: 1
Views: 34

Vaporization and Condensation

When calculating enthalpy of equations, how do we know which enthalpy of vaporizations to subtract or add? Are vaporized molecules always added and condensed ones subtracted, or is it related to the side of the equation it’s on?
by Letty Liu 2C
Sat Feb 08, 2020 9:46 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U at Constant V/P
Replies: 4
Views: 31

Delta U at Constant V/P

What is the internal energy equation at constant volume and pressure? Is it U = q for constant volume and U = q + w at constant pressure?
by Letty Liu 2C
Sat Feb 08, 2020 12:58 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 4C.3
Replies: 1
Views: 24

4C.3

Calculate the final temperature and the change in enthalpy when 765 J of energy is transferred as heat to 0.820 mol Kr(g) at 298 K and 1.00 atm (a) at constant pressure; (b) at constant vol- ume. Treat the gas as ideal.

Which formulas do I use for this question?
by Letty Liu 2C
Fri Feb 07, 2020 4:57 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molecular Interlude
Replies: 1
Views: 14

Molecular Interlude

Can someone explain the Self-test 4B.3A problem, "Estimate the contribution of motion to the molar internal energy of water vapor at 25 C"

I thought we would use the equation 3/2 x (8.3145) x (298.15), but I think I'm missing something.
by Letty Liu 2C
Sun Feb 02, 2020 4:00 pm
Forum: Calculating Work of Expansion
Topic: 4B.9
Replies: 3
Views: 21

4B.9

Did we go over adiabatic processes in class?
by Letty Liu 2C
Sun Feb 02, 2020 3:59 pm
Forum: Calculating Work of Expansion
Topic: 4B.13
Replies: 1
Views: 45

4B.13

Calculate the work for each of the following processes beginning with a gas sample in a piston assembly with T 5 305 K, P 5 1.79 atm, and V 5 4.29 L: (a) irreversible expansion against a constant external pressure of 1.00 atm to a final volume of 6.52 L; (b) isothermal, reversible expansion to a fin...
by Letty Liu 2C
Sun Feb 02, 2020 1:20 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.7
Replies: 1
Views: 11

4A.7

Why does the solutions manual use the specific heat of water with the copper and the specific heat of copper with water?
by Letty Liu 2C
Sun Feb 02, 2020 1:15 am
Forum: Calculating Work of Expansion
Topic: L atm and J
Replies: 3
Views: 24

L atm and J

What is the relationship between L atm and J? How do you convert between the two?
by Letty Liu 2C
Sun Feb 02, 2020 1:08 am
Forum: Calculating Work of Expansion
Topic: Reversible vs. Irreversible
Replies: 1
Views: 20

Reversible vs. Irreversible

Can someone explain the factors that make a reaction irreversible, and why reversible reactions do more work than irreversible ones?
by Letty Liu 2C
Sat Jan 25, 2020 12:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Internal Energy of Systems
Replies: 2
Views: 28

Internal Energy of Systems

Can someone explain the relationship between q, w, and delta U in relation to systems?
by Letty Liu 2C
Sat Jan 25, 2020 12:27 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4B.5
Replies: 1
Views: 30

4B.5

An ideal gas in a cylinder was placed in a heater and gained 5.50 kJ of energy as heat. If the cylinder increased in volume from 345 mL to 1846 mL against an atmospheric pressure of 750. Torr during this process, what is the change in internal energy of the gas in the cylinder? What equation do we u...
by Letty Liu 2C
Sat Jan 25, 2020 12:24 pm
Forum: Phase Changes & Related Calculations
Topic: 4B.3
Replies: 1
Views: 16

4B.3

The internal energy of a system increased by 982 J when it was supplied with 492 J of energy as heat. (a) Was work done by or on the system? (b) How much work was done?

What’s the difference between work being done on or by the system and how do you know?
by Letty Liu 2C
Sat Jan 25, 2020 12:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4B.1
Replies: 1
Views: 19

4B.1

A gas sample in a cylinder is supplied with 524 kJ of energy as heat. At the same time, a piston compresses the gas, doing 340 kJ of work. What is the change in internal energy of the gas during this process? What’s the thought process behind calculations? Is doing work negative and supplied energy ...
by Letty Liu 2C
Sat Jan 25, 2020 11:56 am
Forum: Phase Changes & Related Calculations
Topic: 4A.1
Replies: 1
Views: 10

4A.1

How do we know if a system is closed or open?
by Letty Liu 2C
Fri Jan 17, 2020 10:29 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc & Kp
Replies: 12
Views: 66

Re: Kc & Kp

It depends on the information we’re given. For 5I.17, the problem gives us Kc so we have to use that.
by Letty Liu 2C
Fri Jan 17, 2020 10:27 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium concentration of products
Replies: 2
Views: 21

Re: Equilibrium concentration of products

I believe you can determine the equilibrium concentration of a product based off the concentration of the other.
by Letty Liu 2C
Fri Jan 17, 2020 10:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Exponents and the K constant
Replies: 4
Views: 48

Re: Exponents and the K constant

We use exponents to indicate there are two moles of something reacting to form the molecule. Please correct me if I’m wrong!
by Letty Liu 2C
Fri Jan 17, 2020 10:08 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial concentrations and molar ratios
Replies: 2
Views: 17

Re: Initial concentrations and molar ratios

We can’t determine the initial concentration of the other reactant based off of one reactant because the moles are used for equilibrium. The initial concentrations could range from anything. This is my train of thought but I’m not completely sure.
by Letty Liu 2C
Fri Jan 17, 2020 10:03 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas does not change pressure?
Replies: 7
Views: 47

Re: Inert Gas does not change pressure?

I think inert gases don’t change the pressure of reactions because it’s not directly affecting the concentration of the products/reactants involved in the reaction.
by Letty Liu 2C
Sun Jan 12, 2020 4:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.23
Replies: 2
Views: 19

5I.23

A reaction mixture consisting of 2.00 mol CO and 3.00 mol H2 is placed in a reaction vessel of volume 10.0 L and heated to 1200. K. At equilibrium, 0.478 mol CH4 was present in the system. Determine the value of Kc for the reaction CO(g) 1 3 H2(g) ∆ CH4(g) 1 H2O(g) at 1200. K. Is there a reason why ...
by Letty Liu 2C
Thu Jan 09, 2020 5:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K pressure units
Replies: 3
Views: 23

Re: K pressure units

Since atm and bar are different, I think the values should be in the same units before you start plugging them in.
by Letty Liu 2C
Thu Jan 09, 2020 5:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure
Replies: 4
Views: 39

Re: Pressure

Pressure does not directly affect equilibrium. Only a change in concentration, by lowering the volume, would result in either an increase or decrease in K depending on whether it's the product/reactant being changed.
by Letty Liu 2C
Thu Jan 09, 2020 4:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: kc and kp
Replies: 3
Views: 24

Re: kc and kp

Kc and Kp are related by PV=nRt. You usually only calculate one or the other since one deals with concentrations and the other with pressure. I think you only connect the two together when you're converting one to the other. Hope this helps!
by Letty Liu 2C
Wed Jan 08, 2020 8:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 1
Views: 40

5I.13

In an experiment, 2.0 mmol Cl2(g) was sealed into a reac- tion vessel of volume 2.0 L and heated to 1000. K to study its dissociation into Cl atoms. Use the information in Table 5G.2 to calculate the equilibrium composition of the mixture. I understand how to solve the problem, but I can't find the ...
by Letty Liu 2C
Tue Jan 07, 2020 10:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.3
Replies: 2
Views: 23

5H.3

Use the information in Table 5G.2 to determine the value of K at 300 K for the reaction 2 BrCl(g) 1 H2(g) ∆ Br2(g) 1 2 HCl(g).

Does anybody know how/which numbers to use from the table?
by Letty Liu 2C
Thu Dec 05, 2019 12:17 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength of Acids
Replies: 2
Views: 22

Strength of Acids

Can somebody explain the properties that make an acid strong? I understand that longer, weaker bonds are stronger acids, but this concept is flipped when considering electronegativity. How would we know when to use which property?
by Letty Liu 2C
Wed Dec 04, 2019 11:28 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.5 and example 6B.1
Replies: 1
Views: 22

6B.5 and example 6B.1

Why can we simply subtract the pH from 14 to find pOH, but the steps in example 6B.1 part c is more complicated?
by Letty Liu 2C
Wed Dec 04, 2019 9:38 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.3
Replies: 2
Views: 55

Re: 6B.3

In order to calculate pH you use the concentration of hydronium. Therefore you need to divide mol H3O by L of solution which will give you .025 M H3O. Same for (b) You divide the .005 mol H30 by .250L in order to get the new concentration ([H3O] which gives you .02. Then you can take the -log of th...
by Letty Liu 2C
Wed Dec 04, 2019 3:52 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: J.9
Replies: 1
Views: 37

J.9

Identify the salt that is produced from the acid–base neutralization reaction between (a) potassium hydroxide and acetic acid, CH3COOH; (b) ammonia and phosphoric acid; (c) calcium hydroxide and bromous acid; (d) sodium hydroxide and hydrosulfuric acid, H2S (both H atoms react). Since acid-base neut...
by Letty Liu 2C
Wed Dec 04, 2019 3:43 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: J.9
Replies: 4
Views: 71

Re: J.9

Does anybody have the answers to this problem? I tried to identify the salts but am not sure if I did it right.
by Letty Liu 2C
Sun Dec 01, 2019 11:02 am
Forum: Lewis Acids & Bases
Topic: Neutralization Reactions
Replies: 2
Views: 55

Neutralization Reactions

For problems like "Select an acid and a base for a neutralization reaction that results in the formation of (a) potassium bromide; (b) zinc nitrite; (c) calcium cyanide, Ca(CN)2; (d) potassium phosphate. Write the balanced equation for each reaction." How do we know which atoms are paired ...
by Letty Liu 2C
Sat Nov 30, 2019 2:00 pm
Forum: Naming
Topic: TM in complexes
Replies: 1
Views: 22

TM in complexes

Do the Roman numerals for TMs relate to charges? Like, for sodium bisoxalato(diaqua)ferrate(III), the overall complex is negative because of the -ate, but can iron be negatively charged too?
by Letty Liu 2C
Sat Nov 30, 2019 1:34 pm
Forum: Naming
Topic: 9C.3
Replies: 1
Views: 26

9C.3

Use the information in Table 9C.1 to write the formula for each of the following coordination compounds: (a) potassium hexacyanidochromate(III). I can't find this section in the solutions manual. If potassium is at the front, does that mean the complex has negative charge? Would the potassium be wri...
by Letty Liu 2C
Fri Nov 29, 2019 9:52 am
Forum: Octet Exceptions
Topic: 2.27
Replies: 7
Views: 77

2.27

(a) Draw a Lewis structure for each of the following species: CH31; CH4; CH32; CH2; CH221; CH222. (b) Identify each as a radical or not. After I drew out the Lewis Structures and counted the valence electrons, they all have an even number of electrons and all electrons are paired. Is the answer to q...
by Letty Liu 2C
Thu Nov 28, 2019 6:17 pm
Forum: Hybridization
Topic: 2F.7
Replies: 1
Views: 24

2F.7

Identify the hybrid orbitals used by the atom in boldface red type in each of the following species a) BF3. I know that part of the answer is Bsp^2 ---- F, but how do you figure out what orbital F is? Would it just be F2p?
by Letty Liu 2C
Thu Nov 28, 2019 5:57 pm
Forum: Hybridization
Topic: Unhybridized Orbitals
Replies: 1
Views: 24

Unhybridized Orbitals

When determining hybridization orbitals, do we always put extra electrons into unhybridized p orbitals? Would we ever place them into the unhybridized s ones?
by Letty Liu 2C
Sun Nov 24, 2019 9:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shape
Replies: 3
Views: 33

Re: T Shape

Yes! The T shape is a subcategory under trigonal bipyramidal, has three bonded pairs and two lone pairs, and is AX3E2.
by Letty Liu 2C
Sun Nov 24, 2019 9:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 7
Views: 67

Re: Test 2

Also, does anybody know when we would get them back if we don't have discussion this week?
by Letty Liu 2C
Sun Nov 24, 2019 7:33 pm
Forum: Hybridization
Topic: Hybridization Concept
Replies: 1
Views: 30

Hybridization Concept

When determining the hybridization orbitals, we first write out the atomic orbitals and p always has three orbitals. If p always has three and number of orbitals are conserved in hybridization, how do sp or sp^2 orbitals exist?
by Letty Liu 2C
Mon Nov 18, 2019 3:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Ethene Molecular Shape
Replies: 1
Views: 14

Ethene Molecular Shape

Is ethene made up of two trigonal planars? I am not sure if molecules could have overlapping shapes, and I've only been classifying them with one shape.
by Letty Liu 2C
Sun Nov 17, 2019 11:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.11 Part B
Replies: 2
Views: 29

2E.11 Part B

The question asks for a prediction of the shape of iodine tetrachloride. After drawing the Lewis structure, there are three bonds to chlorine and two lone pairs on iodine.I understand that all the bonds form a trigonal bypyramidal, but why is the ending shape T-shaped and not trigonal planar?
by Letty Liu 2C
Fri Nov 15, 2019 2:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 9
Views: 51

Re: bond angles

Besides for some tetrahedral and trigonal pyramidal bond angles being less than 109.5, are there other molecular shapes we should know for test 2? Also, how would we know the bond angles for more complicated shapes like trigonal bipyramidals?
by Letty Liu 2C
Thu Nov 14, 2019 5:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.7
Replies: 3
Views: 38

2E.7

Part C of this question asks "What values are expected for the OSCl and ClSCl bond angles?"

How do we calculate the bond angles, and why would OSCL and CLSCL have the same answer? Doesn't the difference in atomic attractions affect the resulting bond angle?
by Letty Liu 2C
Mon Nov 11, 2019 7:27 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: 3F.5 [ENDORSED]
Replies: 4
Views: 81

3F.5 [ENDORSED]

Suggest, giving reasons, which substance in each of the following pairs is likely to have the higher normal melting point (Lewis structures may help your arguments): (a) HCl or NaCl; (b) C2H5OC2H5 (diethyl ether) or C4H9OH (butanol); (c) CHI3 or CHF3; (d) C2H4 or CH3OH. Can someone explain how we sh...
by Letty Liu 2C
Mon Nov 11, 2019 5:30 pm
Forum: Dipole Moments
Topic: Dipole-Dipole Forces
Replies: 2
Views: 29

Dipole-Dipole Forces

In figure 3F.5, why is the top polar molecule in a higher energy orientation than the one on the bottom? Shouldn’t the negative and positive ends of polar molecules have greater attraction and energy?
by Letty Liu 2C
Mon Nov 11, 2019 4:59 pm
Forum: Bond Lengths & Energies
Topic: 2.25
Replies: 2
Views: 27

2.25

The problem is “Which bond is longer: (a) the CN bond in HCN or in H3CNH2? (b) The NF bond in NF3 or the PF bond in PF3?”

When I drew out the Lewis structures for the two compounds in part b, they are the same. How do I figure out which one is longer?
by Letty Liu 2C
Thu Nov 07, 2019 5:14 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability of Anions
Replies: 3
Views: 22

Re: Polarizability of Anions

Anions are more polarizable if their electron clouds are bigger, and anions with greater negative charge are larger. So more negative charge means more polarizability.
by Letty Liu 2C
Thu Nov 07, 2019 5:09 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.1
Replies: 3
Views: 68

Re: 1E.1

The angular momentum quantum number is n-1, so going from 1s to 2s would increase this quantum number. For 1s, 1-0=1 and 2s is 2-1=1.
by Letty Liu 2C
Thu Nov 07, 2019 4:54 pm
Forum: Electronegativity
Topic: ionic character
Replies: 9
Views: 91

Re: ionic character

Yes, I believe ionic character is proportional to difference in electronegativity since the atoms will not be sharing the electrons equally if the electronegativity is greater; one atom will have a greater pull.
by Letty Liu 2C
Thu Nov 07, 2019 4:51 pm
Forum: Trends in The Periodic Table
Topic: Ionization energies
Replies: 3
Views: 32

Re: Ionization energies

Nitrogen and oxygen are both in the same p orbital but since oxygen has more electrons to fill the shells than nitrogen, oxygen is more unstable. The three electrons in the 2p orbital for Nitrogen are evenly balanced whereas oxygen as one paired electron with two unpaired. Hope this makes sense!
by Letty Liu 2C
Wed Nov 06, 2019 1:32 pm
Forum: Electronegativity
Topic: Determining Electronegativity
Replies: 4
Views: 56

Determining Electronegativity

If we don’t know the element’s electronegativity, how do we figure out which compounds have a greater difference in electronegativity if they’re near each other on the periodic table? For example, how would we figure out which is more ionic: SiCl or SiBr?
by Letty Liu 2C
Sun Nov 03, 2019 12:34 am
Forum: DeBroglie Equation
Topic: Unit Conversion
Replies: 2
Views: 53

Re: Unit Conversion

You're not necessarily converting seconds to joules. It's more accounting for the fact that the question asks about two seconds and the energy is in terms of joules per second, which is why you multiply the energy by two.
by Letty Liu 2C
Sun Nov 03, 2019 12:29 am
Forum: Properties of Light
Topic: Equations
Replies: 4
Views: 41

Re: Equations

Yes I think they will all be on an equation sheet.
by Letty Liu 2C
Sun Nov 03, 2019 12:28 am
Forum: DeBroglie Equation
Topic: Dino Nuggets 13.2
Replies: 2
Views: 74

Re: Dino Nuggets 13.2

Matt used the equation for light, but potassium ions have mass and should be plugged into the de Broglie equation.
by Letty Liu 2C
Sun Nov 03, 2019 12:25 am
Forum: Photoelectric Effect
Topic: Threshold Energy
Replies: 5
Views: 74

Re: Threshold Energy

Yes, I believe the threshold energy and work function interchangeable terms.
by Letty Liu 2C
Wed Oct 30, 2019 5:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.25 Part C
Replies: 2
Views: 31

1E.25 Part C

For part c, it asks for the notation of Group 5 transition metals. Don't these elements have 3 valence electrons? Shouldn't the answer be (n-1)d^3 ns2?
by Letty Liu 2C
Fri Oct 25, 2019 3:51 pm
Forum: Lewis Structures
Topic: Expanded Valence Shells Example
Replies: 2
Views: 24

Expanded Valence Shells Example

During lecture today, the slide said "EX: S in sulfate ion" and then the rest of the work was for phosphorus pentachloride. Are these separate problems?
by Letty Liu 2C
Fri Oct 25, 2019 3:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge and Molecules
Replies: 4
Views: 34

Re: Formal Charge and Molecules

It's not a coincidence, the formal charges of each atom should always add up to the ionic charge.
by Letty Liu 2C
Fri Oct 25, 2019 3:46 pm
Forum: Octet Exceptions
Topic: Expanded Valence Shells
Replies: 4
Views: 27

Re: Expanded Valence Shells

I am also confused about this. Dr. Lavelle said elements in period 3 or higher can accommodate more than 8 electrons, but I don't know if all the elements could have expanded valence shells.
by Letty Liu 2C
Fri Oct 25, 2019 3:43 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 8
Views: 73

Re: Drawing Lewis Structures

Hydrogen can never be a central atom.
by Letty Liu 2C
Thu Oct 24, 2019 11:49 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 2
Views: 38

Electron Configurations

For 1E.7, is the configuration for nitrogen representing an excited state of the atom because the second spin on 2p is not pointing up?
by Letty Liu 2C
Fri Oct 18, 2019 11:20 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 3d and 4s States
Replies: 2
Views: 28

3d and 4s States

I'm confused about the energy levels with 4s and 3d. How is 4s before 3d if it is a higher energy level? Could someone explain the reasoning behind this concept and how it applies to the elements we went over in class?
by Letty Liu 2C
Fri Oct 18, 2019 10:40 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: electron spin arrows
Replies: 6
Views: 37

Re: electron spin arrows

I think it helps to draw the electrons out as arrows on available orbitals, and make sure to fill up all the orbitals with one arrow before parting them up.
by Letty Liu 2C
Fri Oct 18, 2019 10:33 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Two Exceptions
Replies: 2
Views: 30

Re: Two Exceptions

The two exceptions are referring to the Cu and Cr elements. Cu is (Ar) 3d^10 4s^1, and Cr is (Ar) 3d^5 4s^1
by Letty Liu 2C
Thu Oct 17, 2019 2:08 pm
Forum: Properties of Electrons
Topic: 1B.15
Replies: 1
Views: 52

1B.15

For part c, it asks “what is the wavelength of the radiation that caused photoejection of the electron?” I know that it’s asking for the wavelength of the total energy after looking at the solutions manual, but I originally interpreted it as asking for the wavelength of the energy required to remove...
by Letty Liu 2C
Mon Oct 14, 2019 4:58 pm
Forum: Properties of Light
Topic: 1A.11
Replies: 2
Views: 43

1A.11

I understand how the series are related to energy levels, but I don't understand the answer for this question. "In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series or Lyman series, as shown in Fig. 1A.10). What...
by Letty Liu 2C
Sun Oct 13, 2019 11:30 am
Forum: Properties of Light
Topic: Rydberg constant
Replies: 7
Views: 71

Re: Rydberg constant

Isabella Dal Porto 1I wrote:Why is the Rydberg equation only applicable towards hydrogen atoms?


I believe it's because the Rydberg equation was derived from a spectroscopic experiment using hydrogen as the atom. Correct me if I'm wrong please!
by Letty Liu 2C
Sun Oct 13, 2019 11:20 am
Forum: Properties of Light
Topic: e=hv
Replies: 7
Views: 91

Re: e=hv

Is the E=hV formula derived from the photoelectric experiment?
by Letty Liu 2C
Sun Oct 13, 2019 11:15 am
Forum: Properties of Light
Topic: 1A3
Replies: 5
Views: 59

Re: 1A3

The speed of light is a constant, so it can never change or be affected by the frequency.
by Letty Liu 2C
Sun Oct 13, 2019 11:11 am
Forum: Properties of Light
Topic: 1A.3
Replies: 3
Views: 46

Re: 1A.3

I'm also confused about the relationship between the frequency of electromagnetic radiation and the extent of change in the electrical field.
by Letty Liu 2C
Fri Oct 11, 2019 4:39 pm
Forum: Properties of Light
Topic: Quanta vs Photon
Replies: 4
Views: 45

Re: Quanta vs Photon

I believe photons are particles representing a quantum of light, so photons are made up of quanta (which are quantities of energy).

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