## Search found 61 matches

Fri Mar 15, 2019 3:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 5
Views: 208

### Re: Test 2

So can we assume we always assume that when the pH is 7 then it will be pH + pH = 14 in which we will divide by 2.
Fri Mar 15, 2019 10:11 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 5
Views: 208

### Re: Test 2

How is there 2pH?
Fri Mar 15, 2019 10:09 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 3
Views: 190

### Re: Test 2

When would ΔG=0?
Wed Mar 13, 2019 2:15 pm
Forum: First Order Reactions
Topic: 7B.9
Replies: 2
Views: 122

### 7B.9

For the first order reaction A \rightarrow 3B + C, When [A]0 = .015 mol/l, the concentration of B increases to .018 mol/ L in 3.0 min. a) What is the rate of constant for the reaction expressed as the rate of loss of A? I got the answer 1.7 minutes but the answer is .17 minutes. I was wondering how ...
Tue Mar 12, 2019 11:37 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 3
Views: 190

### Test 2

7b. The combustion of a gas used to heat a BBQ at a pool party.

Would this be a spontaneous reaction?
Tue Mar 12, 2019 11:28 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 5
Views: 208

### Test 2

5. The ionic dissociation of water is given by the following reaction: The ΔH for the reaction is 58kJ/mol. The Kw for the reaction at 25°C is 10^-14. Is a pH of 7 acidic or basic at 30°C? 2H2O(l) \leftrightarrow H30+(aq) + OH-(aq) What is the pH? I used the nerst equation but I'm not getting the ri...
Tue Mar 12, 2019 11:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 Cell Diagram
Replies: 3
Views: 185

### Test 2 Cell Diagram

When do we use a comma for the cell diagram?
Do we also use a conductor when there is no solid present?
Thu Mar 07, 2019 12:34 am
Forum: General Rate Laws
Topic: 7A.15
Replies: 1
Views: 88

### 7A.15

How do you find the order for the reactants and overall order?

I'm confused on when to use each experiment?
Thu Mar 07, 2019 12:09 am
Forum: General Rate Laws
Topic: 7A.13
Replies: 3
Views: 189

### 7A.13

In the reaction CH3Br + OH- $\rightarrow$ CH3OH + Br-, when the OH- concentration alone was doubled, the rate doubled; when the CH3Br concentration alone was increased by a factor of 1.2, the rate increased by a factor of 1.2. Write the rate law for the reaction.

How do you determine the rate law?
Thu Feb 28, 2019 12:19 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5
Replies: 1
Views: 86

### 6L.5

Write the half reactions, balanced equation for the cell reaction and the cell diagram.
d) Au^+(aq) $\rightarrow$ Au(s) + Au^3+(aq)

Why do we use the solid Au for the anode?
Wed Feb 27, 2019 11:33 pm
Forum: Balancing Redox Reactions
Topic: 6K.5
Replies: 2
Views: 111

### Re: 6K.5

Thank you I forgot about the negative charge on OH so I put the electrons on the wrong side.
Wed Feb 27, 2019 10:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.1
Replies: 1
Views: 85

### 6L.1

When calculating the standard reaction GIbbs free energy how do we find n?
Wed Feb 27, 2019 8:29 pm
Forum: Balancing Redox Reactions
Topic: 6K.5
Replies: 2
Views: 111

### 6K.5

Balance each of the following skeletal equations by using oxidation and reduction half reactions.

a) O3 + Br- $\rightarrow$ O2 + BrO3-

How do you balance the half reaction of O3$\rightarrow$ O2?
Wed Feb 27, 2019 6:43 pm
Forum: Balancing Redox Reactions
Topic: 6K.3
Replies: 1
Views: 87

### 6K.3

Balance each of the following skeletal equations by using oxidation and reduction half reactions.

d) Cl2 $\rightarrow$ HClO + Cl2
Tue Feb 26, 2019 10:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm
Replies: 5
Views: 205

### Midterm

What does it mean for part 1c to comment on the relative stability of the reactants and products?
Mon Feb 11, 2019 12:38 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: 4G. 2B 7th edition
Replies: 2
Views: 104

### 4G. 2B 7th edition

Suggest a reason why the entropy of ice is nonzero at T= 0; think about how the structure of ice is affected by the hydrogen bonds.
Mon Feb 11, 2019 12:13 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: 4G. 1B 7th edition
Replies: 1
Views: 98

### 4G. 1B 7th edition

Calculate the entropy of a sample of a solid in which it is supposed that a substituted benzene molecule, C6H5F, may be found in any one of six orientations with the same energy at T=0. Suppose there is 1.0 mol of molecules in the sample.

Why is one mole of the molecule multiplied with the equation?
Mon Feb 11, 2019 12:02 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies
Replies: 10
Views: 336

### Bond enthalpies

To solve for bond enthalpies, do we have to know the lewis structure of the molecules?
Wed Feb 06, 2019 11:35 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 7th edition 4F.9
Replies: 1
Views: 100

### 7th edition 4F.9

Calculate the change in entropy when the pressure of 1.5mol Ne(g) is decreased isothermally from 15.0 atm to .500 atm. Assume ideal behavior.
Wed Jan 30, 2019 8:18 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 4B.3
Replies: 1
Views: 122

### 4B.3

The internal energy of a system increased by 982 J when it was supplied with 492 J of energy as heat.
How much work was done?
I got that work done was 490J but the book answer is 9.0 x 10^2J.
Wed Jan 30, 2019 6:54 pm
Forum: Calculating Work of Expansion
Topic: 4A.3 7th edition
Replies: 2
Views: 104

### 4A.3 7th edition

Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump is 3.0 cm and the pump is depressed 20.cm with a pressure of 2.00 atm.
How do you calculate the change in internal energy?
Wed Jan 30, 2019 6:46 pm
Forum: Calculating Work of Expansion
Topic: 4A.3 7th Ed
Replies: 6
Views: 196

### Re: 4A.3 7th Ed

Why is it -πr^2?
Mon Jan 21, 2019 5:49 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Post Assessment
Replies: 1
Views: 99

### Post Assessment

Determine the shift in equilibrium, if any, which will occur for the following reactions when the temperature is increased a) Photosynthesis: 6 CO2 (g) + 6 H2O (l) ⇌ C6H12O6(s) + 6 O2 (g) delta H° = +2802 kJ.mol-1 b) The hydrolysis of ATP: ATP (aq) + H2O (l) ⇌ ADP + PO42-(aq) delta H° = -30 kJ.mol-1...
Sun Jan 20, 2019 7:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Post Assessment
Replies: 1
Views: 112

### Post Assessment

A researcher fills a 1.00 L reaction vessel with 1.84 x 10-4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place. 2BrCl(g) ⇌ Br2 (g) + Cl2(g) I keep getting 19.8 but I know tha...
Wed Jan 16, 2019 8:34 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th Edition 5J.1
Replies: 3
Views: 94

### 7th Edition 5J.1

CO + H2O ⇌ CO2 +H2
c) If the concentration of CO is increased, what happens to the concentration of H2?
Why would H2 increase?
Wed Jan 16, 2019 8:28 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5I.7 7th edition
Replies: 2
Views: 104

### Re: 5I.7 7th edition

Thanks, I did forget to convert.
Wed Jan 16, 2019 7:34 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5I.7 7th edition
Replies: 2
Views: 104

### 5I.7 7th edition

A reaction vessel of volume .500L at 700. K contains 1.20 mmol SO2, .50 mmol O2, and .10 mmol SO3. At 700 K, Kc= 1.7 x 10^6 for the equilibrium 2SO2 + O2⇌ 2SO3.
Calculate the reaction quotient Qc.
I got 6.9 x 10^-3 but the answer was 6.9.
Wed Jan 16, 2019 12:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.7 7th edition
Replies: 1
Views: 106

### 5I.7 7th edition

If Q=1.0 for the reactin N2 + O2 $\rightarrow$ 2NO at 25 C will the reaction have a tendency to form products or reactants, or will it be at equilibrium?

How to you find the K value of the equation?
Wed Jan 16, 2019 12:28 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Post Assessment
Replies: 1
Views: 68

### Post Assessment

Write the equilibrium constant expression for the unbalanced chemical equation.
NO2 (g) + H2 (g) ⇌ NH3 (g) + H2 O (l).

Thu Jan 10, 2019 4:33 pm
Forum: Ideal Gases
Topic: HW # 5G.5 7th edition
Replies: 2
Views: 132

### HW # 5G.5 7th edition

c) Assuming that the initial pressure of X2 was .10 bar, calculate the value of K for the decomposition.
Thu Jan 10, 2019 1:01 am
Forum: Ideal Gases
Topic: Post Assessment
Replies: 3
Views: 138

### Post Assessment

Why are equilibrium constants useful?
Thu Dec 06, 2018 8:01 pm
Forum: Calculating the pH of Salt Solutions
Topic: 6D.11
Replies: 1
Views: 272

### 6D.11

Decide whether an aqueous solution of each of the following salts has a pH equal to , greater than, or less than 7? If pH> 7 or pH< 7, write a chemical equation to justify your answer. f) Cu(NO3)2 I don't understand how f) is less than 7. Also how would you write the chemical equation to justify?
Mon Dec 03, 2018 4:57 pm
Forum: Naming
Topic: 9C.3 7th edition
Replies: 1
Views: 85

### 9C.3 7th edition

a)potassium hexacynidochromate (III) - the answer is K3 [Cr(CN)6] How come the formulas don't have a charge when writing from the coordination compounds and why is it K3? d)soduim bisoxaltodiaquaferrate(III) - Na[Fe(OH2)2(CO3)2] Does the order of the ligands matter because I mixed up the (CO3)2 and ...
Sun Dec 02, 2018 6:31 pm
Forum: Naming
Topic: Naming and Charges
Replies: 1
Views: 105

### Naming and Charges

In lecture, there was an example of [Ni(CN)6]-2 and the name was tetracynonicelate(II). I was confused on the -ate part because I know you add the -ate if the metal has a negative charge but I thought Ni would have a positive charge.
Thu Nov 29, 2018 10:13 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Charges
Replies: 4
Views: 188

### Charges

How do you find the charges of each of the elements with the complexes?
Thu Nov 29, 2018 9:48 pm
Forum: Naming
Topic: Coordination Number
Replies: 3
Views: 175

### Coordination Number

How do you find out the coordination number?
Mon Nov 26, 2018 11:05 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: Ion- Ion and Dipole- Dipole
Replies: 1
Views: 48

### Ion- Ion and Dipole- Dipole

How do you tell if molecules have an ion- ion force or a dipole- dipole force? Like I don't understand why HCl is dipole- dipole.
Mon Nov 26, 2018 7:32 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: Boiling Point
Replies: 3
Views: 516

### Boiling Point

Rank the following in terms of increasing boiling point:
LiCl, C3H7OH, C4H8, N2

Does boiling point depend on the strength of the intermolecular force?
Mon Nov 26, 2018 7:16 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: intermolecular forces
Replies: 1
Views: 98

### intermolecular forces

Are ion- ion forces stronger than ion- dipole forces?
Sun Nov 25, 2018 11:13 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 3
Views: 176

### Polarizability

Which one has higher polarizability?
a) Be 2+ or Li 1+
b) Mg 2+ or Be 2+

I tried using the ideas of the polarizability trend but it didn't work.
Sat Nov 24, 2018 10:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E. 18
Replies: 1
Views: 87

### 2E. 18

d) Draw the lewis structure, VESPR formula, molecular shape, and bond angles: N2O
Why doesn't the lewis structure for N2O have a lone pair?
Sat Nov 24, 2018 9:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.9
Replies: 1
Views: 55

### 2E.9

What value is expected for the ClICl bond angle?
Sat Nov 24, 2018 7:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape vs molecular geometry
Replies: 3
Views: 73

### molecular shape vs molecular geometry

What is the difference between molecular shape and geometry? Which one depends on lone pairs?
Mon Nov 12, 2018 7:30 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Compounds 2D3
Replies: 2
Views: 169

### Ionic Compounds 2D3

How do you determine which compounds have ionic bonds?
And why is BaBr2 primarily more ionic than BeBr2 and BBr3?
Mon Nov 12, 2018 2:53 am
Forum: Ionic & Covalent Bonds
Topic: Boiling Point
Replies: 3
Views: 279

### Boiling Point

How do you determine which compounds have a higher boiling point such as CHCl3 and CCl4?
Sun Nov 04, 2018 5:28 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 114

### Electron Affinity

Which has a higher electron affinity, chlorine (Cl) or Neon (Ne)?

I know that chlorine has the higher electron affinity but why?
Sun Nov 04, 2018 5:08 pm
Forum: Trends in The Periodic Table
Replies: 4
Views: 179

What is the effect of electrons on the size of the atom?
Fri Nov 02, 2018 5:22 pm
Forum: Quantum Numbers and The H-Atom
Topic: Test #2
Replies: 1
Views: 134

### Test #2

What type of orbital with principal quantum number 4 has one more nodal plan than the 4s orbital?
Fri Nov 02, 2018 4:42 pm
Forum: Quantum Numbers and The H-Atom
Topic: Determining electrons
Replies: 3
Views: 362

### Determining electrons

How do you find the possible number of electrons given by quantum numbers?

Ex: n=2, l= 1
n=4, l=0, ml=-2, ms= -1/2
Fri Oct 26, 2018 5:53 pm
Forum: Quantum Numbers and The H-Atom
Topic: Test #2
Replies: 2
Views: 144

### Test #2

When writing the quantum numbers for an orbital, do you include all the values of m?
Fri Oct 26, 2018 5:36 pm
Forum: Quantum Numbers and The H-Atom
Topic: Test #2
Replies: 3
Views: 203

### Test #2

What does degeneracy mean?
Mon Oct 22, 2018 10:10 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: post assessment
Replies: 1
Views: 65

### post assessment

In the hydrogen atomic spectrum, what is the wavelength of light associated with the n = 2 to n = 1 electron transition?

When I worked this problem out, I got -1.22 x 10^-7 as the answer but this isn't correct.
Thu Oct 18, 2018 7:08 pm
Forum: DeBroglie Equation
Topic: post assessment #29
Replies: 2
Views: 149

### post assessment #29

If a proton and an electron have the same de Broglie wavelength do they have the same speed?
Sun Oct 14, 2018 6:29 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: post assessment #40
Replies: 2
Views: 72

### post assessment #40

What is the wavelength of radiation emitted by a hydrogen atom in a transition from the n = 6 to the n = 5 energy level?
Sun Oct 14, 2018 4:29 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: post assessment #28
Replies: 1
Views: 65

### post assessment #28

The meter was defined in 1963 as 1,650,763.73 wavelengths of radiation emitted by krypton-86 (it has since been redefined). What is the wavelength of this krypton-86 radiation? To what region of the electromagnetic spectrum does this wavelength correspond (i.e. infrared, ultraviolet, x-ray, etc.)? W...
Sat Oct 13, 2018 6:01 pm
Forum: Photoelectric Effect
Topic: Module Question 28 Part A
Replies: 1
Views: 69

### Re: Module Question 28 Part A

I used the equation Ek= 1/2mv^2 for this problem. The problem already gives you the velocity and the mass of the electron is 9.109 x 10^-31 kg (which is a constant provided in the back of the textbook). I got 1.98 x 10^-19 J as the answer.
Tue Oct 09, 2018 6:32 pm
Forum: Photoelectric Effect
Topic: post assessment
Replies: 2
Views: 121

### post assessment

In a photoelectric experiment light hits a metal surface and if the energy of the ________ light is ________ enough it causes electrons to be ejected from the metal surface. A. outgoing, large B. outgoing, small C. incoming, large D. incoming, small E. None of the above I know that the first blank i...
Sat Oct 06, 2018 1:49 am
Forum: Molarity, Solutions, Dilutions
Topic: post assessment
Replies: 1
Views: 83

### post assessment

5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentration of the solution in the 2nd flask? Molar Masses: K (39.10 g/mol), Mn (54.94 g/mol), O (16.00 g/mol) Why do you u...
Sat Oct 06, 2018 1:00 am
Forum: Molarity, Solutions, Dilutions
Topic: post assessment
Replies: 1
Views: 61

### post assessment

What volume of 0.0380 M KMnO4 is needed to prepare 250 mL of 1.50 x 10-3 M KMnO4?
Would you just need to set them equal to each other?
Thu Oct 04, 2018 5:30 pm
Forum: Limiting Reactant Calculations
Topic: Post Assessment 26 [ENDORSED]
Replies: 1
Views: 89

### Post Assessment 26[ENDORSED]

Based on the molar ratios in a balanced chemical equation a student expects 0.20 moles of product. If the molar mass of the product is 81 g.mol-1 what is the theoretical yield?
Do I just multiply the expected moles with the actual product? And why?
Thu Oct 04, 2018 3:45 pm
Forum: Empirical & Molecular Formulas
Topic: Problem F.1b
Replies: 3
Views: 171

### Problem F.1b

My calculations for the answer were off by the hundredth decimal point. For example I calculated 78.96% when the answer is 78.90%. Would I get the answer wrong?