## Search found 53 matches

Wed Mar 14, 2018 12:59 am
Forum: Second Order Reactions
Topic: Test 3 #8
Replies: 2
Views: 217

### Re: Test 3 #8

Since you have the half life and initial concentration, you can solve for k using the equation for second order half-life

t(1/2) = 1/(k[A]naught)

After solving for k, you can use the second order equation

1/[A] = kt + 1/[A]naught

Plug in 2.00M for [A], 5.00M for [A]naught, and k
then solve for t
Wed Mar 14, 2018 12:53 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2 Question 8b
Replies: 9
Views: 590

### Test 2 Question 8b

Wednesday in Dane's section Consider the following unbalanced half reactions Hg2Cl2(s) + 2e- -> 2Hg(l) + 2Cl-(aq) Enaught = +0.27V 2H+(aq) + 2e- -> H2(g) Enaught = 0.00V b) If PH2 = 2.0 bar, [H+] = 3.16x10^4 M and [Cl] = 0.75M, what is Q? For this problem, how to you deal with partial pressure and M...
Wed Mar 14, 2018 12:43 am
Forum: Balancing Redox Reactions
Topic: Test 2 Question 8
Replies: 2
Views: 128

### Re: Test 2 Question 8

I think for #8 they already gave you the balanced equation. If they didn't then you have to balance it using the steps for balancing redox equations. To find the number of electrons exchanged, you can look at the charges on both side of the equation. If you see any discrepancies between the charges ...
Mon Mar 05, 2018 6:37 pm
Forum: General Rate Laws
Topic: unique reaction rate sign
Replies: 2
Views: 106

### Re: unique reaction rate sign

I think they are always positive. I am pretty sure Dr. Lavelle said something about there is no such thing as a negative rate, at least for what we are doing
Mon Mar 05, 2018 6:33 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 918897

### Re: Post All Chemistry Jokes Here

Mon Mar 05, 2018 6:23 pm
Forum: Zero Order Reactions
Topic: Units of k
Replies: 12
Views: 591

### Re: Units of k

The units for zero order is mol/(L*s)
Tue Feb 27, 2018 8:53 pm
Forum: Experimental Details
Topic: Homework Problem 15.3 Part C
Replies: 5
Views: 358

### Re: Homework Problem 15.3 Part C

Unique rate is calculated by dividing the rate of a species by its stoichiometric coefficient
Tue Feb 27, 2018 8:47 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalytic Reactions
Replies: 2
Views: 110

### Re: Catalytic Reactions

A catalyst is something that increases the rate of a reaction. I think photosynthesis is an example
Tue Feb 27, 2018 8:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram order
Replies: 4
Views: 142

### Re: Cell diagram order

In the textbook, it ways to write the oxidized form, reduced form; however in the solutions manual, sometimes they have the reduced form before the oxidized form, so I am not sure
Tue Feb 20, 2018 4:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.23c
Replies: 2
Views: 123

### Re: Homework 14.23c

I guess I am trying to ask how do you know what order you put everything in in cell diagrams.

I thought that ions in solution are written in the order oxidized state, reduced state, so I was wondering why Pu3+(aq), Pu4+(aq) written with the reduced state first
Tue Feb 20, 2018 12:19 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.17
Replies: 1
Views: 95

### Homework 14.17

14.17 (a) Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride. (b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagram). anode: Fe 2+(aq) -> Fe 3+(aq) + e-...
Tue Feb 20, 2018 12:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt in Cell diagrams
Replies: 4
Views: 181

### Re: Pt in Cell diagrams

Pt is necessary when both the oxidized and reduced species are in the same solution
Tue Feb 20, 2018 12:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.23c
Replies: 2
Views: 123

### Homework 14.23c

14.23 For each reaction that is spontaneous under standard conditions, write a cell diagram, determine the standard cell potential, and calculate delta G naught for the reaction: c) Cr2O7^2- (aq) + 14 H+ (aq) + 6 Pu3+ (aq) S -> 6 Pu4+ (aq) + 2 Cr3+ (aq) + 7 H2O(l) The cell diagram is Pt(s)IPu3+(aq),...
Tue Feb 13, 2018 3:37 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Is it possible to force a reaction that will decrease the entropy of the universe?
Replies: 1
Views: 73

### Re: Is it possible to force a reaction that will decrease the entropy of the universe?

The textbook says that "The natural progression of a system and its surroundings (which together make up “the universe”) is from order to disorder, from organized to random, from lower to higher entropy." Thus, I think that decreasing the entropy of the universe defies the second law of th...
Tue Feb 13, 2018 2:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: constant pressure
Replies: 2
Views: 217

### Re: constant pressure

If you are given enthalpy (H), then you can assume constant pressure, since q=deltaH under constant pressure
Tue Feb 13, 2018 2:35 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Isothermal Systems and deltaU
Replies: 2
Views: 102

### Re: Isothermal Systems and deltaU

Yes I think so

The textbook says "deltaU=0 for the isothermal expansion (or compression) of an ideal gas"
Tue Feb 06, 2018 4:31 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.1
Replies: 4
Views: 192

### Re: 9.1

I think it is talking about the surroundings
Tue Feb 06, 2018 4:25 pm
Forum: Balancing Redox Reactions
Topic: Ozone oxidation number
Replies: 2
Views: 88

### Re: Ozone oxidation number

I think it's 0
Tue Feb 06, 2018 4:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Bruin Cast
Replies: 5
Views: 279

### Re: Bruin Cast

I do not think it is
Mon Jan 29, 2018 3:31 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: A spontaneous reaction
Replies: 7
Views: 201

### Re: A spontaneous reaction

A spontaneous reaction is a reaction that is favorable (with a negative deltaG)
Mon Jan 29, 2018 3:08 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Homework 9.5 [ENDORSED]
Replies: 11
Views: 410

### Re: Homework 9.5[ENDORSED]

We use S=-q/T for the entropy at 800 K because heat released, and we use S=q/T for the entropy at 200 K because heat is absorbed by the reservoir
Mon Jan 29, 2018 3:05 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible vs. Reversible Pathways
Replies: 3
Views: 131

### Re: Irreversible vs. Reversible Pathways

Also, more work is done in reversible pathways than in irreversible pathways.
Tue Jan 23, 2018 8:15 pm
Forum: Phase Changes & Related Calculations
Topic: How to differentiate when to use certain formulas
Replies: 3
Views: 164

### Re: How to differentiate when to use certain formulas

I think some of the main equations we need to know are
q=nC(deltaT)
w=-P(deltaV)
(deltaU)=q+w
Tue Jan 23, 2018 8:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units
Replies: 2
Views: 76

### Re: Units

I think my ta said they would not take off points for either, but we should use kj/mol
Tue Jan 23, 2018 8:11 pm
Forum: Administrative Questions and Class Announcements
Topic: When can we pick up our finals from Chem 14A?
Replies: 3
Views: 315

### Re: When can we pick up our finals from Chem 14A?

In the email that Dr. Lavelle sent us, he said we can pick them up at 4006 Young Hall, Week 3 Winter quarter. But I do not know what time specifically
Fri Jan 19, 2018 10:33 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: C(v) and C(p)
Replies: 3
Views: 129

### Re: C(v) and C(p)

Gasses have Cp and Cv (specific heats at constant pressure and volume), but I think solids and liquids only have one value for specific heat
Fri Jan 19, 2018 10:24 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capcity for Water
Replies: 8
Views: 263

### Re: Heat Capcity for Water

Specific heat capacity for water(solid) is 2.03 J/g°C, water(liquid) is 4.184 J/g°C, and water(vapor) is 2.01 J/g°C
Fri Jan 19, 2018 10:10 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Internal Energy/Open System
Replies: 4
Views: 194

### Re: Internal Energy/Open System

You can increase the temperature of an open system and it will increase its internal energy, but I am not sure how effective it is to, say, heat up an open beaker where the heat can just leave
Wed Jan 10, 2018 3:57 pm
Forum: Phase Changes & Related Calculations
Topic: Exothermic Rxn
Replies: 6
Views: 275

### Re: Exothermic Rxn

Not all exothermic reactions are spontaneous, meaning that the reaction will occur without outside influence. Just because a reaction is exothermic doesn't mean that its reactants cannot be found naturally.
Wed Jan 10, 2018 3:50 pm
Forum: Phase Changes & Related Calculations
Topic: qp=deltaH
Replies: 8
Views: 386

### Re: qp=deltaH

DeltaH is what people usually use, so I don't think we will use qp
Wed Jan 10, 2018 3:43 pm
Forum: Phase Changes & Related Calculations
Topic: Endo and Exothermic Ways to Remember
Replies: 28
Views: 2467

### Re: Endo and Exothermic Ways to Remember

Also in chemistry, exothermic and endothermic refers to the system. Exothermic releases heat (so the surroundings feel warm) and endothermic requires heat (so the surroundings feel cool)
Mon Dec 04, 2017 7:19 pm
Forum: Lewis Acids & Bases
Topic: Writing equations with acids and bases
Replies: 5
Views: 212

### Re: Writing equations with acids and bases

I think we need to know what the strong acids/bases are
Mon Dec 04, 2017 6:58 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: EDTA
Replies: 2
Views: 142

### Re: EDTA

It can bind twice at the N and 4 times at the O
Thu Nov 30, 2017 11:23 am
Forum: Naming
Topic: Suffixes
Replies: 4
Views: 289

### Re: Suffixes

The textbook says that "If the complex has an overall negative charge (an anionic complex), the suffix -ate is added to the stem of the metal’s name," so it does not matter if the ligand has a negative charge or not. Because 17.29d has an overall positive charge, no suffix is added to the ...
Thu Nov 30, 2017 11:14 am
Forum: Naming
Topic: Trans & Cis Naming
Replies: 3
Views: 170

### Re: Trans & Cis Naming

I think so? Otherwise you wouldn't know the placement of the molecules?
Tue Nov 21, 2017 8:39 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining the direction of reaction
Replies: 1
Views: 81

### Re: Determining the direction of reaction

To determine the direction of the reaction when given the INITIAL concentrations and a K value, find Q, which equals [C][D]/[A][B] (it looks like k) for A+B->/<-C+D.
And if Q<K, reaction will go forward; Q>K reaction will reverse; Q=K at equilibrium
Tue Nov 21, 2017 8:35 am
Forum: Conjugate Acids & Bases
Topic: Strong vs Weak Acids/bases
Replies: 4
Views: 275

### Re: Strong vs Weak Acids/bases

I think the strength of acids is based on percent of dissociation; strong acids are assumed to be 100% dissociated in aqueous environments. Strong bases are usually salts with -OH (there are exceptions)
Wed Nov 15, 2017 6:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determing Molecular Shape
Replies: 2
Views: 121

### Re: Determing Molecular Shape

I think the one electron should be put on the less electronegative atom (central atom) because the more electronegative one will be more attractive to electrons and have its octet filled
Wed Nov 15, 2017 6:36 pm
Forum: Sigma & Pi Bonds
Topic: When looking at at molecule how can I determine when they will form sigma and pi bonds?
Replies: 3
Views: 167

### Re: When looking at at molecule how can I determine when they will form sigma and pi bonds?

I think all you have to do is determine how many single/double/triple bonds there are. Because there are two double bonds in CO2, there are two sigma and two pi bonds since each double bond has one sigma and one pi bond
Tue Nov 07, 2017 10:14 pm
Forum: Lewis Structures
Topic: Homework 3.33 C
Replies: 2
Views: 165

### Re: Homework 3.33 C

The central atom is always the atom with the lowest ionization energy
Tue Nov 07, 2017 9:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The valence electron of Cu and Br
Replies: 2
Views: 343

### Re: The valence electron of Cu and Br

Valence electrons are usually in the outermost s or p block. There is one valence electron in Cu (because of 4s^2) and 7 valence electrons in Br (because of 4s^1 4p^5). They could be in the d block though. For example, Fe has 2 (4s^2) or 3 valence electrons (3d^6 because there are two electrons in o...
Thu Nov 02, 2017 12:31 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: More Polarizable/Polarizing Power
Replies: 6
Views: 319

### Re: More Polarizable/Polarizing Power

Yes I think that's right
Thu Nov 02, 2017 12:29 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy in Orbitals
Replies: 2
Views: 127

### Re: Energy in Orbitals

No. Within the same energy level, s<p<d<f
Tue Oct 24, 2017 11:50 pm
Forum: Trends in The Periodic Table
Topic: 2.59
Replies: 1
Views: 102

### Re: 2.59

They are isoelectronic, but being isoelectronic only means that they have the same amount of electrons, but they still have different properties. Because they have the same number of electrons and Cl- has more protons, the radius for Cl- is the smallest because there are more positive energy attract...
Tue Oct 24, 2017 11:43 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: #55 part c
Replies: 1
Views: 119

### Re: #55 part c

5p is higher in energy than 5d, so the p shell in group 5 appears after the transition metals
Tue Oct 24, 2017 11:37 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: #55 d
Replies: 3
Views: 175

### Re: #55 d

A full d^10 is more stable than d^9, so the electron configuration is ns^1(n-1)d^10
Wed Oct 18, 2017 10:22 pm
Forum: Properties of Electrons
Topic: 1.57
Replies: 3
Views: 258

### 1.57

1.57 Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0, and 410.2 nm. What is the wavelength of the next line in the series?
How do you set up this problem?
Mon Oct 16, 2017 6:43 pm
Forum: Properties of Electrons
Topic: Hydrogen Series
Replies: 4
Views: 259

### Hydrogen Series

In the textbook it said that the Lyman series is in the UV region and the Balmer series in the visible light. But it didn't mention the Paschen nor Brackett series. Do you think we need to know which region they are in?
Thu Oct 12, 2017 6:42 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 918897

### Re: Post All Chemistry Jokes Here

"Susie, these past two years have been amazing, but recently, I just feel like I've been living a half life..."
Mon Oct 09, 2017 10:11 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Models of Atoms- Question 2.31
Replies: 4
Views: 218

### Re: Models of Atoms- Question 2.31

I think you are getting n and l mixed up. n is the number of subshells (the number in front of the letter). The reason there's no 2d orbital is that n=2 consists of only 2s and 2p. l describes the shape, which correlates with the letters, meaning that when you try to interpret quantum numbers, you w...
Thu Oct 05, 2017 9:26 pm
Forum: Molarity, Solutions, Dilutions
Topic: E. 23
Replies: 2
Views: 327

### Re: E. 23

Oh my gosh I wrote down CuBr3 instead of CuBr2. Thanks!
Thu Oct 05, 2017 9:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: E. 23
Replies: 2
Views: 327

### E. 23

Question:
Calculate the amount (in moles) of (a) Cu2 ions in 3.00 g of CuBr2; (b) SO3 molecules in 7.00 x 10^2 mg of SO3; (c) F ions in 25.2 kg of UF6; (d) H2O in 2.00 g of Na2CO3 10H2O.

Hey can someone show me how to set up part a? I seem to be having a brain fart...
Thu Oct 05, 2017 6:01 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Calculations Post-Module Assessment
Replies: 2
Views: 218

### Re: Limiting Reactant Calculations Post-Module Assessment

The information about the temperature and pressure isn't really relevant right now