Exam 1 Practice Test PDF

Preview

Summary

Dr. Gartner Gen Chem 150 Exam 1 Practice Test...

Description

CHEM 150 Spring 2019

Exam 1 Practice Test 1. In a coffee cup calorimeter, 14.45 g of solid nickel hydroxide was added to 0.500L of HBr solution (density of 1.03 g/mL). After the reaction, the temperature of the solution raised from 16.25oC to 41.5oC. The specific heat capacity of the solution is 4.184 J g -1 oC-1. Calculate the ΔH for 3.25 moles of Ni(OH) 2. Ni(OH) 2(s) + HBr(aq) → NiBr2(aq) + H2O(l)

2. Consider the following reaction: 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O (l) a. Calculate the change in entropy and change in enthalpy for this reaction.

b. Determine if this reaction will be spontaneous at 85oC.

c. Circle one: The potential energy of the reactants is greater than / less than / equal to the potential energy of the products. Explain your choice.

d. Determine the change in internal energy for the reaction of 18.0 g of C 2H2 at 85oC.

CHEM 150 Spring 2019 3. In lab, a 41.9 g piece of 135C iron metal is dropped into 165 g of 27.4C water. Once thermal equilibrium is reached, what will be the final temperature of the water?

4. Consider the following reaction: H2O (l) + Na2CO3(s) + CO2 (g) → 2NaHCO3(s) ΔHo= -129 kJ a. Is the spontaneity of this reaction temperature dependent? Explain your choice in words.

b. At what temperature in oC does the spontaneity change (if at all)? Show your work.

c. Circle one: For this reaction, the entropy of the surroundings will increase / decrease / remain constant. Explain your choice.

d. What is the maximum amount of useful work that can be obtained from this reaction with 2.86 moles of Na2CO3?

CHEM 150 Spring 2019 5. A 0.580 g sample of benzoic acid (C6H5COOH) was combusted in a bomb calorimeter at an initial temperature of 22.7C. The final temperature was 32.4C. The molar E for this combustion is -3227 kJ/mol. Calculate the heat capacity of the calorimeter in units of kJ/ C.

6. Consider the following reactions: 2NO(g) + O2(g) → 2NO2(g)

ΔH= -116 kJ

2N2 (g) + 5O2(g) + 2H2O (l) → 4HNO3(aq)

ΔH= -256 kJ

N2(g) + O2(g) → 2NO(g)

ΔH= +183 kJ

Calculate the ΔH for the following reaction: 3NO2(g) + H2O (l) → 2HNO3(aq) + NO(g)

7. Circle one: The change in internal energy for a reaction can be quantified using a bomb calorimeter / coffee cup calorimeter. Explain your choice and why the other option is incorrect.

CHEM 150 Spring 2019 8. Predict if the following reaction would be endothermic or exothermic. Explain your choice. FeCl3(s) → Fe(s) + 3Cl(s)

9. You have a hot copper pot of 1150 g at 234C. Copper has a specific heat capacity of 387 J/kgK. You add 127.5 g of an unknown liquid into the copper pot. Before adding the unknown liquid, it had a temperature of 305 K. The unknown liquid heats up to a temperature of 128C. a. Determine the identity of the unknown liquid.

b. Calculate the heat capacity of the liquid.

sH2O= 4.184 J g-1 oC-1

So(C2H2(g))= 200.8 J/molK

sFe= 0.4498 J g-1 oC-1

So(CO2(g))= 213.6 J/molK

ΔHf(C2H2(g))= 226.75 kJ/mol

So(H2O(l))= 69.96 J/molK

ΔHf(CO2(g))= -393.5 kJ/mol

So(Na2CO3(s))= 136 J/molK

ΔHf(H2O(l))= -285.9 kJ/mol

So(NaHCO 3(s))= 102 J/molK...