Question 1

How much heat is absorbed when 30.00 g of C(s)reacts in the presence of excess SO2(g)to produce CS2(l)and CO(g)according to the following chemical equation? 5 C(s)+ 2 SO2(g)→ CS2(l)+ 4 CO(g)ΔH° = 239.9 kJ

Accepted Answer

A) 119.8 kJ 
B) 239.9 kJ 
C) 599.2 kJ 
D) 1439 kJ

Question 2

A process is carried out at constant pressure.Given that 0 > ΔH > ΔE,

Accepted Answer

A) the system absorbs heat and expands during the process. 
B) the system absorbs heat and contracts during the process. 
C) the system loses heat and expands during the process. 
D) the system loses heat and contracts during the process.

Question 3

He gas is contained in a one-liter flask that is connected to an empty one-liter flask with a closed stopcock between the two flasks.When the stopcock is opened some of the He enters the evacuated flask.For this system

Accepted Answer

A) ΔH is negative and ΔS is zero. 
B) ΔH is zero and ΔS is positive. 
C) ΔH is zero and ΔS is negative. 
D) ΔH is positive and ΔS is positive.

Question 4

-What are the signs of ΔH and ΔS for the reaction represented in the above drawing?

Accepted Answer

A) ΔH = +,ΔS = + 
B) ΔH = +,ΔS = - 
C) ΔH = -,ΔS = + 
D) ΔH = -,ΔS = -

Question 5

Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide according to the chemical equation shown below.When 0.015 mol of Na is added to 100.00 g of water,the temperature of the resulting solution rises from 25.00°C to 31.45°C.If the specific heat of the solution is 4.18 J/(g ∙ °C),calculate ΔH for the reaction,as written. 2 Na(s)+ 2 H2O(l)→ 2 NaOH(aq)+ H2(g)ΔH = ?

Accepted Answer

A) -5.41 kJ 
B) -90.0 kJ 
C) -180 kJ 
D) -360 kJ

Question 6

Which is a measure of the sum of the kinetic and potential energies of each particle in the system?

Accepted Answer

A) E,the internal energy 
B) G,the Gibbs free energy 
C) H,the enthalpy 
D) T,the temperature

Question 7

It takes 15.5 kJ of energy to raise the temperature of 200 g of benzene from 25.0°C to 70.0°C.What is the specific heat of benzene?

Accepted Answer

A) 1.10 J/(g ∙ °
C)  
B) 1.72 J/(g ∙ °
C)  
C) 3.48 J/(g ∙ °
C)  
D) 5.41 J/(g ∙ °
C)

Question 8

Is a hydroelectric dam a form of kinetic or potential molecular energy?

Accepted Answer

The answer of Is a hydroelectric dam a form of...

Question 9

When 50.0 mL of 0.400 M Ca(NO3)2 is added to 50.0 mL of 0.800 M NaF,CaF2 precipitates,as shown in the net ionic equation below.The initial temperature of both solutions is 25.00°C.Assuming that the reaction goes to completion,and that the resulting solution has a mass of 100.00 g and a specific heat of 4.18 J/(g ∙ °C),calculate the final temperature of the solution. Ca2+(aq)+ 2 F-(aq)→ CaF2(s)ΔH° = -11.5 kJ

Accepted Answer

A) 24.45°C 
B) 25.55°C 
C) 26.10°C 
D) 26.65°C

Question 10

At a constant pressure of 2.50 atm what is the enthalpy change ΔH for a reaction where the internal energy change ΔE is 58.0 kJ and the volume increase is 12.6 L? (1 L·atm = 101.325 J. )

Accepted Answer

A) 39.1 kJ 
B) 54.8 kJ 
C) 61.2 kJ 
D) 76.9 kJ

Exam 9: Thermochemistry: Chemical Energy

How much heat is absorbed when 30.00 g of C(s) reacts in the presence of excess SO₂(g) to produce CS₂(l) and CO(g) according to the following chemical equation? 5 C(s) + 2 SO₂(g) → CS₂(l) + 4 CO(g) ΔH° = 239.9 kJ

A process is carried out at constant pressure.Given that 0 > ΔH > ΔE,

He gas is contained in a one-liter flask that is connected to an empty one-liter flask with a closed stopcock between the two flasks.When the stopcock is opened some of the He enters the evacuated flask.For this system

-What are the signs of ΔH and ΔS for the reaction represented in the above drawing?

Which is a measure of the sum of the kinetic and potential energies of each particle in the system?

It takes 15.5 kJ of energy to raise the temperature of 200 g of benzene from 25.0°C to 70.0°C.What is the specific heat of benzene?

Is a hydroelectric dam a form of kinetic or potential molecular energy?

At a constant pressure of 2.50 atm what is the enthalpy change ΔH for a reaction where the internal energy change ΔE is 58.0 kJ and the volume increase is 12.6 L? (1 L·atm = 101.325 J. )

Exam 9: Thermochemistry: Chemical Energy

How much heat is absorbed when 30.00 g of C(s) reacts in the presence of excess SO2(g) to produce CS2(l) and CO(g) according to the following chemical equation? 5 C(s) + 2 SO2(g) → CS2(l) + 4 CO(g) ΔH° = 239.9 kJ

A process is carried out at constant pressure.Given that 0 > ΔH > ΔE,

He gas is contained in a one-liter flask that is connected to an empty one-liter flask with a closed stopcock between the two flasks.When the stopcock is opened some of the He enters the evacuated flask.For this system

-What are the signs of ΔH and ΔS for the reaction represented in the above drawing?

Which is a measure of the sum of the kinetic and potential energies of each particle in the system?

It takes 15.5 kJ of energy to raise the temperature of 200 g of benzene from 25.0°C to 70.0°C.What is the specific heat of benzene?

Is a hydroelectric dam a form of kinetic or potential molecular energy?

At a constant pressure of 2.50 atm what is the enthalpy change ΔH for a reaction where the internal energy change ΔE is 58.0 kJ and the volume increase is 12.6 L? (1 L·atm = 101.325 J. )

How much heat is absorbed when 30.00 g of C(s) reacts in the presence of excess SO₂(g) to produce CS₂(l) and CO(g) according to the following chemical equation? 5 C(s) + 2 SO₂(g) → CS₂(l) + 4 CO(g) ΔH° = 239.9 kJ