CH 233 Midterm 2 S20

Entropy

100

This entropy can never decrease.

What is the entropy of the universe?

200

Which is the correct Equation?

a. ΔS_uni=ΔS_sys + ΔS_surr

b. ΔS_sys = ΔS_uni + ΔS_surr

c. ΔS_uni = ΔS_sys - ΔS_surr

d. ΔS_surr = ΔS_uni - ΔS_sys

A and/or D.

300

Does absolute molar entropy increase or decrease with molecular complexity? Why?

Molar entropy increases with molecular complexity because energy can have a larger distribution over more molecules/bonds.

400

The standard molar entropy for diamond is 2.4 J/mol K. Calculate the number of microstates available to a single carbon atom in diamond, and the number of available microstates for one mole of carbon atoms in diamond.

(Double Jeopardy)

Part I: 1.322 microstates available per atom

Part II: e^{1.74*10^23} microstates available per mole

500

Calculate W for a system where you have five particles. Two of the particles must have 9 J of energy, one must have 5 J, one must have 3 J, and the other must have 10 J.

What is W=60?

Gibb's Free Energy

100

List 3 differences between the equilibrium dependent equations of ΔG^o and ΔG_rxn.

ΔG^o depends on K and is calculated with a negative sign. ΔG_rxn is calculated with Q and is dependent on ΔG^o.

200

Determine the signs of ΔS^o and ΔH^o for the combustion of propane given the following equation:

C_3H_8(g)+5O_2(g)->3CO_2(g)+4H_2O(g)

Why is ΔS^o positive and ΔH^o negative?

300

When the sign for ΔH^o is positive and the sign for ΔS^o is negative, this will be the for ΔG^o. 

What is positive?

400

Calculate the change in entropy that occurs in the surroundings when acetone (C3H6O) freezes at its melting point (-87.4 degrees C) ΔH_fus for acetone is 4.20 kJ/mol.

22.6 J/mol*K

500

The standard free energy change for the hydrolysis of ATP is -30.5 kJ.

ATP(aq)+H2O(l)→ADP(aq)+Pi(aq)

In a particular cell, the concentrations of ATP, ADP, and P_i are 0.0028 M , 0.0014 M , and 0.0047 M , respectively. Calculate the free energy change for the hydrolysis of ATP under these conditions. (Assume a temperature of 298 K.)

-45.5 kJ or -4.55*10⁴ J

Electro Chemistry

100

Fill in the blanks: During reduction, we ______ electrons. During oxidation, we ______ electrons. 

Gain, lose

200

This is the oxidation state of O₂. Explain why.

How much is 0 because O₂ is an element. 

300

These are the steps to balancing a redox reaction in a basic solution.

(Does not need to be answered in the form of a question, but extra 50 points if you can)

How do you separate into half reactions, balance all elements except oxygen, add in electrons, balance charges with hydroxide, balance oxygen with water, and then combine to cancel the electrons?

400

Determine which element is going through reduction/oxidation. CO + I₂O₅ -> CO₂ + I₂

Carbon is oxidized, iodine is reduced. 

500

Balance the Following Reaction in Base: 

C₆H₁₂O₆(aq) + VO₄ ³⁻(aq) -> CO₂(𝑔) + V²⁺(aq)

(Double Jeopardy)

C₆H₁₂O₆(aq) + 8VO₄ ³⁻(aq) +14H₂O(l)-> 6CO₂(𝑔) + 8V²⁺(aq)+40OH^-(aq)