The time to heat the sample to its melting point is to be calculated. Concept introduction: Specific heat capacity ( c ) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K . The formula to calculate heat required is as follows: q = ( mass ) ( c ) ( T 2 − T 1 ) (1) Here, T 2 is the final temperature. T 1 is the initial temperature. q is the heat released or absorbed. c is the specific heat capacity of the substance. The formula to calculate heat at phase change is as follows: q = ( mass ) ( Δ H ) (2) Here, Δ H is the enthalpy change.

Question

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Answer 1

Question

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Conclusion

The time taken to melt 25 g sample is 10 min.

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.

q3=(25 g)(0.5 J/g⋅°C)(100 °C−85 °C)=187.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from 85 °C to 100 °C is calculated as follows:

Time=(187.5 J450 J/min)≈0.4 min.

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 2

Conclusion

The temperature versus time plot for the given sample represents the phase change.

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Answer 2

Question

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Conclusion

The time taken to melt 25 g sample is 10 min.

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.

q3=(25 g)(0.5 J/g⋅°C)(100 °C−85 °C)=187.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from 85 °C to 100 °C is calculated as follows:

Time=(187.5 J450 J/min)≈0.4 min.

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 2

Conclusion

The temperature versus time plot for the given sample represents the phase change.

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Answer 3

Question

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Conclusion

The time taken to melt 25 g sample is 10 min.

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.

q3=(25 g)(0.5 J/g⋅°C)(100 °C−85 °C)=187.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from 85 °C to 100 °C is calculated as follows:

Time=(187.5 J450 J/min)≈0.4 min.

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 2

Conclusion

The temperature versus time plot for the given sample represents the phase change.

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Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Answer 4

Question

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Conclusion

The time taken to melt 25 g sample is 10 min.

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.

q3=(25 g)(0.5 J/g⋅°C)(100 °C−85 °C)=187.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from 85 °C to 100 °C is calculated as follows:

Time=(187.5 J450 J/min)≈0.4 min.

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 2

Conclusion

The temperature versus time plot for the given sample represents the phase change.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Answer 5

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Conclusion

The time taken to melt 25 g sample is 10 min.

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.

q3=(25 g)(0.5 J/g⋅°C)(100 °C−85 °C)=187.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from 85 °C to 100 °C is calculated as follows:

Time=(187.5 J450 J/min)≈0.4 min.

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 2

Conclusion

The temperature versus time plot for the given sample represents the phase change.

Answer 6

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

Answer 7

Chapter 12, Problem 12.142P

a.

Interpretation Introduction

Interpretation:

The time to heat the sample to its melting point is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

Answer 8

a.

Expert Solution

Answer to Problem 12.142P

The time to heat the sample to its melting point is 1.1 min.

Answer 9

a.

Expert Solution

Answer 10

a.

Expert Solution

Answer 11

Expert Solution

Answer 12

Explanation of Solution

Substitute 25 g for mass, 1.0 J/g⋅°C for c, −20.0 °C for T2 and −40.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of sample from −40.0 °C to −20.0 °C.

q=(25 g)(1.0 J/g⋅°C)((−20.0 °C)−(−40.0 °C))=500 J

Constant rate of heating is 450 J/min. The time to heat the sample to its melting point is calculated as follows:

Time=(500 J450 J/min)=1.1111 min≈1.1 min.

Answer 13

Conclusion

The given sample reaches its melting point by heating for 1.1 min.

Answer 14

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Conclusion

The time taken to melt 25 g sample is 10 min.

Answer 15

(b)

Interpretation Introduction

Interpretation:

The time taken to melt the sample is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

Answer 16

(b)

Expert Solution

Answer to Problem 12.142P

The time taken to melt the sample is 10 min.

Answer 17

(b)

Expert Solution

Answer 18

(b)

Expert Solution

Answer 19

Expert Solution

Answer 20

Explanation of Solution

Substitute 25 g for mass and 180 J/g for ΔHfus° in the equation (2) to change the phase of solid sample at −20.0 °C to liquid sample at −20.0 °C.

q=(25 g)(180 J/g)=4500 J

Constant rate of heating is 450 J/min. The time taken to melt the sample is calculated as follows:

Time=(4500 J450 J/min)=10 min

Answer 21

Conclusion

The time taken to melt 25 g sample is 10 min.

Answer 22

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.

q3=(25 g)(0.5 J/g⋅°C)(100 °C−85 °C)=187.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from 85 °C to 100 °C is calculated as follows:

Time=(187.5 J450 J/min)≈0.4 min.

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 2

Conclusion

The temperature versus time plot for the given sample represents the phase change.

Answer 23

(c)

Interpretation Introduction

Interpretation:

A curve of temperature vs. time for the entire heating process is to be calculated.

Concept introduction:

Specific heat capacity (c) of a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 K. The formula to calculate heat required is as follows:

q=(mass)(c)(T2−T1) (1)

Here,

T2 is the final temperature.

T1 is the initial temperature.

q is the heat released or absorbed.

c is the specific heat capacity of the substance.

The formula to calculate heat at phase change is as follows:

q=(mass)(ΔH) (2)

Here,

ΔH is the enthalpy change.

Answer 24

(c)

Expert Solution

Answer to Problem 12.142P

The curve of temperature vs. time for the entire heating process is as follows:

CHEMISTRY(LOOSELEAF) W/CONNECT+EBOOK, Chapter 12, Problem 12.142P , additional homework tip 1

Answer 25

(c)

Expert Solution

Answer 26

(c)

Expert Solution

Answer 27

Expert Solution

Answer 28

Explanation of Solution

Substitute 25 g for mass, 2.5 J/g⋅°C for c, 85 °C for T2 and −20.0 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from −20.0 °C to 85 °C.

q1=(25 g)(2.5 J/g⋅°C)(85 °C−(−20.0 °C))=6562.5 J

Constant rate of heating is 450 J/min. The time to increase the temperature of the sample from −20.0 °C to 85 °C is calculated as follows:

Time=(6562.5 J450 J/min)≈15 min

Substitute 25 g for mass and 500 J/g for ΔHvap in the equation (2) to change the phase of the liquid sample at 85 °C to gas sample at 85 °C.

q2=(25 g)(500 J/g)=12500 J

Constant rate of heating is 450 J/min. The time to change the phase of the liquid sample at 85 °C to gas sample at 85 °C is calculated as follows:

Time=(12500 J450 J/min)≈28 min

Substitute 25 g for mass, 0.5 J/g⋅°C for c, 100 °C for T2 and 85 °C for T1 in the equation (1) to calculate the heat required to increase the temperature of the sample from 85 °C to 100 °C.