Search found 21 matches

by Yiwei Zhou 2I
Fri Mar 16, 2018 4:22 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: 14.119
Replies: 2
Views: 387

14.119

14.119 One stage in the extraction of gold from rocks involves dissolving the metal from the rock with a basic solution of sodium cyanide that has been thoroughly aerated. This stage results in the formation of soluble Au(CN)2- ions. The next stage is to reduce gold to the metal by the addition of z...
by Yiwei Zhou 2I
Thu Mar 15, 2018 1:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Questions in the second test
Replies: 2
Views: 131

Questions in the second test

Q: Rank the following in order of increasing oxidizing power.

a).Mn,Ag,Ti

Could someone answer this question and also explain the solving process?
Thanks so much!
by Yiwei Zhou 2I
Wed Feb 21, 2018 3:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: TEXTBOOK 14.57
Replies: 1
Views: 78

TEXTBOOK 14.57

Aqueous solutions of (a) Mn2; (b) Al3; (c) Ni2; (d) Au3 with concentrations of 1.0 molL1 are electrolyzed at pH  7. For each solution, determine whether the metal ion or water will be reduced at the cathode. What is the standard reduction potential of water? 2H2O + 2e- = H2 + 2OH-  -0.83V ...
by Yiwei Zhou 2I
Wed Feb 21, 2018 12:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: TEXTBOOK 14.25
Replies: 2
Views: 153

TEXTBOOK 14.25

14.25 Arrange the following metals in order of increasing strength as reducing agents for species in aqueous solution: (a) Cu, Zn, Cr, Fe; (b) Li, Na, K, Mg; (c) U, V, Ti, Al; (d) Ni, Sn, Au, Ag When we compare the standard reduction potential of Cu, which data should we use? Why? (Cu+) + (e-) = Cu ...
by Yiwei Zhou 2I
Mon Feb 12, 2018 3:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: TEXTBOOK 11.83
Replies: 1
Views: 87

TEXTBOOK 11.83

"Calculate the equilibrium constant at 25 C and at 150 C for each of the following reactions, using data available in Appendix 2A"

When can we calculate the equilibrium constant deltaG with Gibbs Free Energy of Formation in Appendix 2?
When can't we?
by Yiwei Zhou 2I
Sun Jan 28, 2018 10:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity [ENDORSED]
Replies: 4
Views: 166

Re: Heat capacity [ENDORSED]

I think that specific heat capacities will be given in the constants and formulas sheet or be mentioned in the question.
by Yiwei Zhou 2I
Wed Jan 24, 2018 2:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Textbook 8.113
Replies: 1
Views: 97

Textbook 8.113

8.113 Water gas is an inexpensive, low-grade fuel that can be made from coal. (a) Is the production of water gas exothermic or endothermic? The reaction is C+H2O=CO+H2 The solution manual solves it by using standard enthalpy of formation. Can we solve it by using bond enthalpies? (I tried but the re...
by Yiwei Zhou 2I
Sun Jan 21, 2018 11:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.117
Replies: 2
Views: 158

Re: 8.117

For the production of 1.00 mol H2, you have 1/3 mol CH4, 1/3 mol H20, and 1/3 mol CO2 produced. So the net mole of gas is 2/3 mol.
by Yiwei Zhou 2I
Sun Jan 21, 2018 11:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies
Replies: 4
Views: 186

Re: Bond enthalpies

I think we would be given certain bond enthalpies value instead of a whole chart
by Yiwei Zhou 2I
Sun Jan 14, 2018 5:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Heating curves
Replies: 1
Views: 100

Re: Heating curves

It means that in a given heat amount, one with lower heat capacity changes the temperature more rapidly than the one with higher heat capacity.
by Yiwei Zhou 2I
Sun Jan 14, 2018 5:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73.b
Replies: 3
Views: 148

Re: 8.73.b

Because 4 hydrogen atoms are bounded on C atom so the bond enthalpy should be multiplied by 4. You can also count every bond, broken or not, in the reactants and the products that it takes less time to think about the bond breaking and forming process.
by Yiwei Zhou 2I
Sat Dec 09, 2017 12:55 pm
Forum: Bronsted Acids & Bases
Topic: Textbook 12.115 [ENDORSED]
Replies: 1
Views: 149

Textbook 12.115 [ENDORSED]

12.115 Acetic acid is used as a solvent for some reactions between acids and bases. (a) Nitrous acid and carbonic acids are both weak acids in water. Will either of them act as strong acid in acetic acid? Explain your answer. (b) Will ammonia act as a strong or weak base in acetic acid? Explain your...
by Yiwei Zhou 2I
Sat Dec 09, 2017 12:05 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.27 part B
Replies: 1
Views: 113

Re: 12.27 part B

250.0 means it is a 250.0-mL volumetric flask. We need to divide the moles by volume to get the H3O+ concentration.
by Yiwei Zhou 2I
Fri Dec 08, 2017 11:17 pm
Forum: Biological Examples
Topic: Question on practice exam [ENDORSED]
Replies: 2
Views: 280

Question on practice exam [ENDORSED]

22. A protein like histidine can bind at one site to the heme complex iron to from myoglobin. How many O2 molecules can myoglobin bind? How many myoglobin form a hemoglobin?

Can someone explain this question for me? Thanks so much!
by Yiwei Zhou 2I
Sun Dec 03, 2017 5:06 pm
Forum: Lewis Acids & Bases
Topic: H+ as Lewis acid/base [ENDORSED]
Replies: 2
Views: 467

Re: H+ as Lewis acid/base [ENDORSED]

It is a Bronsted acid/base reaction if H+ is referred as a proton.
by Yiwei Zhou 2I
Sun Dec 03, 2017 5:01 pm
Forum: Conjugate Acids & Bases
Topic: Identifying Conjugates
Replies: 2
Views: 150

Re: Identifying Conjugates

A conjugate acid contains one more H atom and one more + charge than the base that formed it. A conjugate base contains one less H atom and one more - charge than the acid that formed it. Take a example: HCO₃⁻ + H₂O → H₂CO₃ + OH⁻ base + acid → Conj A + Conj B HCO₃⁻ becomes H₂CO₃. It has one more H a...
by Yiwei Zhou 2I
Mon Nov 27, 2017 4:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question about Table 11.2 in textbook
Replies: 1
Views: 148

Question about Table 11.2 in textbook

What is the difference between K and Kc+ in the Table 11.2 in the textbook?
by Yiwei Zhou 2I
Sun Nov 26, 2017 8:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 45 part c
Replies: 1
Views: 103

Re: 45 part c

Cl2's dissociation has a smaller equilibrium constant so Cl2 is more stable.
by Yiwei Zhou 2I
Sun Nov 26, 2017 8:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 11.29
Replies: 2
Views: 132

Re: Problem 11.29

Though it is not an assigned problem, to calculate K you need the format of deltaG = - RTlnK.
The Gibbs free energy of formation of 1 mol NO can be found from appendix 2 in the textbook.
by Yiwei Zhou 2I
Sun Nov 19, 2017 11:20 pm
Forum: Hybridization
Topic: Electron density question
Replies: 4
Views: 262

Re: Electron density question

Single, double and triple bonds count as one region of electron density.
Paired elections or an unpaired electron also count as one region of electron density.
by Yiwei Zhou 2I
Sun Nov 19, 2017 10:51 pm
Forum: Hybridization
Topic: Purpose of hybridization [ENDORSED]
Replies: 5
Views: 819

Re: Purpose of hybridization [ENDORSED]

Hybridization is actually the way we explain the VSEPR model. We first discover some molecular geometry. For example, the C-H bond in CH4 has equal length, but the valence electrons are not in the same energy level; and later we use hybridization as an explanation that hybrid orbitals are assumed to...

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