Search found 22 matches

by jennifer_zhou2C
Mon Mar 07, 2016 3:57 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Solution Manual Error Not Yet Spotted? (8.63c)
Replies: 1
Views: 261

Solution Manual Error Not Yet Spotted? (8.63c)

I don't know whether anybody else has posted about this, but I saw this error today after review some chemistry problems and did not see it in the solutions manual error page. In Chapter 8, #63c, the problem asks you to find the standard reaction enthalpy. The equation is: H2S(aq)+2KOH(aq)->K2S(aq)+...
by jennifer_zhou2C
Sun Mar 06, 2016 10:40 am
Forum: Phase Changes & Related Calculations
Topic: 2010 Final Exam Q1B: Which is greater delta H?
Replies: 1
Views: 250

2010 Final Exam Q1B: Which is greater delta H?

The part I'm struggling with is the second part of the question which asks: Which requires more heat: Breaking one mole of carbon-carbon single bonds or melting one mole ice? The answer states "breaking a covalent bond" but aren't both of these bonds O-H and C-C covalent bonds?? I put that...
by jennifer_zhou2C
Thu Feb 25, 2016 10:55 am
Forum: *Aldehydes
Topic: Chapter 2 Number 42: Naming an aldehyde
Replies: 1
Views: 523

Chapter 2 Number 42: Naming an aldehyde

The question asks: A methyl derivative of citronellal is being tested as a stronger insect repellent against mosquitoes that carry malaria. Write the IUPAC name for: o=CH-CH(CH3)-CH(CH3)-CH2-CH2-CH=C(CH3)2. I got 2,3,7-trimethyloct-6-en-1-al. The book states that the answer is 2,3,7-trimethyloct-6en...
by jennifer_zhou2C
Tue Feb 23, 2016 2:09 pm
Forum: *Alkanes
Topic: Aliphatic Hydrocarbons
Replies: 1
Views: 266

Re: Aliphatic Hydrocarbons

An aliphatic hydrocarbon actually means that the hydrocarbon does not have a ring present in the structure. This can include double and triple bonds as long as there is no ring.
by jennifer_zhou2C
Tue Feb 16, 2016 11:37 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrolytic Cell
Replies: 1
Views: 328

Electrolytic Cell

Why is an electrolytic cell different than a galvanic cell? How does it work?
by jennifer_zhou2C
Tue Feb 16, 2016 11:34 pm
Forum: General Rate Laws
Topic: Rate Laws in Graphs
Replies: 1
Views: 410

Rate Laws in Graphs

I know that 2nd order rate laws must be graphed differently in order to determine k, but what is the difference between making a graph molarity vs time, 1/M vs time, and ln(M) vs time?s
by jennifer_zhou2C
Sun Feb 14, 2016 4:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrodes and Cell Diagrams
Replies: 2
Views: 299

Re: Electrodes and Cell Diagrams

Galvanic cells are positive cells. The overall charge on a galvanic cell is positive simply because that's the definition of a galvanic cell. Keep in mind that galvanic cells can refer to fuel cells, rocket fuel, a battery cell, or many other names.
by jennifer_zhou2C
Sun Feb 14, 2016 4:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to separate solids in a cell diagram
Replies: 3
Views: 440

Re: How to separate solids in a cell diagram

Why would you even need the Pt? One solution is aqueous and the other is solid, and the solid would function as the electrode. Am I missing something?
by jennifer_zhou2C
Fri Jan 29, 2016 7:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Residual Molar Entropy
Replies: 3
Views: 453

Re: Residual Molar Entropy

Use the equation klnW. (Because many organic compounds specify how to draw each one, there are limited ways of drawing them). Count up the different ways and use the equation.
by jennifer_zhou2C
Fri Jan 29, 2016 7:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Quiz 1 Preparation Question (Gibbs Free Energy?)
Replies: 2
Views: 631

Re: Quiz 1 Preparation Question (Gibbs Free Energy?)

Bonds are being broken, so it is endothermic. The delta H would be positive.
by jennifer_zhou2C
Fri Jan 29, 2016 7:09 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Constant Pressure, Constant Volume Work
Replies: 1
Views: 363

Re: Constant Pressure, Constant Volume Work

If gas is generated, then work is done so you include work in the change in internal energy.
by jennifer_zhou2C
Fri Jan 29, 2016 7:07 pm
Forum: Calculating Work of Expansion
Topic: calculating work
Replies: 2
Views: 321

Re: calculating work

Reversible uses more work. The equation for that is w=-nRTln(V2/V1). For irreversible, use the equation w=P delta V. The pressure of work is the pressure of surroundings.
by jennifer_zhou2C
Sun Nov 15, 2015 9:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework Question 11.63: a question on assuming
Replies: 1
Views: 256

Homework Question 11.63: a question on assuming

After following the ICE method, I reached an impasse with my calculator when I did the calculation: x^{2}-(1.28\cdot 10^{-33})x^{2} and got 1 (which I should have known seeing as anything 10^{33} will be really close to 0). Anyways, my question is when is the correct time to practice assumin...
by jennifer_zhou2C
Sun Nov 15, 2015 9:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question on a step in 11.61?
Replies: 2
Views: 364

Re: Question on a step in 11.61?

I believe the solutions manual is wrong. I literally multiplied the calculations they had put together and they didn't even get the numbers they posted. I checked my math roughly about 100 times because I thought I was wrong.
by jennifer_zhou2C
Mon Nov 02, 2015 3:46 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Idean's Chemistry Review Question #8
Replies: 1
Views: 294

Idean's Chemistry Review Question #8

The question asks, "What is the minimum uncertainty in the position of an electron confined to within the diameter of a zinc atom with an uncertainty in velocity of 3.00x10 6 \pm 2.24* 10^{6} ms? The diameter of a zinc atom is 139 pm. Are we certain that the electron is confined within the atom...
by jennifer_zhou2C
Mon Nov 02, 2015 3:41 pm
Forum: Ionic & Covalent Bonds
Topic: Drawing Ionic Bonds
Replies: 1
Views: 370

Drawing Ionic Bonds

How would you draw ionic bonds since the bond is actually electrostatic attraction?
by jennifer_zhou2C
Fri Oct 30, 2015 12:30 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7862
Views: 1100879

Re: Chemistry Jokes

Heisenberg calls up Pauli and says, "I have an idea that will revolutionize quantum physics!" to which Pauli replies, "Are you certain?!"
Heisenberg says, "Not at all!"
by jennifer_zhou2C
Sun Oct 25, 2015 11:45 pm
Forum: Sigma & Pi Bonds
Topic: Conceptual Explanation of Pi Bonds
Replies: 1
Views: 307

Re: Conceptual Explanation of Pi Bonds

The first bond formed between two atoms is always a sigma bond. This creates an head-on overlapping between bonds. The pi bonds are then formed because the next two regions of electron density are perpendicular to the head-on sigma bonds. Think of two right angles facing each other. Imagine that eac...
by jennifer_zhou2C
Sat Oct 17, 2015 10:16 pm
Forum: Octet Exceptions
Topic: Homework Problem 3.123: Radicals
Replies: 1
Views: 343

Re: Homework Problem 3.123: Radicals

Actually, the carbon should bond twice with one of the oxygens, leaving another oxygen with 7 valence electrons. This makes it a radical because there is one uncompleted octet. Because the structure is not ionized, there is no way for the oxygen to gain another electron as it does not apply for the ...
by jennifer_zhou2C
Sun Oct 04, 2015 9:13 pm
Forum: Empirical & Molecular Formulas
Topic: M21
Replies: 2
Views: 438

Re: M21

Sorry. I made a typo. Find out the percentage of the element in the molecule. You can do that by dividing the mass of the element by the mass of the sample given.
by jennifer_zhou2C
Sun Oct 04, 2015 9:10 pm
Forum: Empirical & Molecular Formulas
Topic: M21
Replies: 2
Views: 438

Re: M21

Yes. Attempt to find out how much each element would weigh, then find out the percentage of element in each atom. Convert percentages to whole numbers (pretending the sample is made of 100 grams is easiest) and then find the empirical/molecular formula from then on.
by jennifer_zhou2C
Sun Oct 04, 2015 9:07 pm
Forum: Significant Figures
Topic: Multiplying/Dividing with Sig Figs
Replies: 1
Views: 380

Multiplying/Dividing with Sig Figs

When I use stoichiometry, I cross multiply and cancel in order to cancel out the units. Because of this I often divide or multiply by 1 unit integers. Does this mean when using significant figures, I have to round to 1 sig fig?

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