Chapter U5, Problem C18.3RE

(a)

Interpretation Introduction

Interpretation: The number of calories of energy transferred by rise the temperature of 20g of water by $25°\text{C}$ needs to be calculated.

Concept Introduction: Thermal energy is total kinetic energy that combined with motions and mass of particles in a sample of matter measured as heat energy.

Answer to Problem C18.3RE

Number of calories of energy transferred by rise the temperature of 20g of water by $25°\text{C}$ is 500 cal.

Explanation of Solution

Given mass of water (m) = 20g

Temperature change $\left(\Delta \text{T}\right)=25°\text{C}$

Specific heat of water is $\text{1}\text{cal}/\text{g}\cdot °\text{C}$

The equation of heat is as follows:

  $\text{H=mCΔT}$

Here H is heat, m is mass, C is specific heat and T is temperature.

Put the values in above equation is as follows:

  $\begin{array}{c}\text{H=20}\cancel{\text{g}}\times \text{1}\frac{\text{cal}}{\text{g×}\cancel{\text{°C}}}\times \text{25}\cancel{°\text{C}}\\ \text{=500cal}\end{array}$

Thus number of calories of energy transferred is 500 cal.

(b)

Interpretation Introduction

Interpretation: The number of calories of energy transferred by rise the temperature of 200g of copper by $50°\text{C}$ needs to be calculated.

Concept Introduction: Thermal energy is total kinetic energy that combined with motions and mass of particles in a sample of matter measured as heat energy.

Answer to Problem C18.3RE

Number of calories of energy transferred by rise the temperature of 200g of copper by $50°\text{C}$ is 900 cal.

Explanation of Solution

Given mass of water (m) = 200g

Temperature change $\left(\Delta \text{T}\right)=50°\text{C}$

Specific heat of copper is $0.09\text{cal}/\text{g}\cdot °\text{C}$

The equation of heat is as follows:

  $\text{H=mCΔT}$

Here H is heat, m is mass, C is specific heat and T is temperature.

Put the values in above equation is as follows:

  $\begin{array}{c}\text{H=200}\cancel{\text{g}}\times 0.09\frac{\text{cal}}{\text{g×}\cancel{\text{°C}}}\times 50\cancel{°\text{C}}\\ \text{=900cal}\end{array}$

Thus number of calories of energy transferred is 900 cal.

(c)

Interpretation Introduction

Interpretation: The number of calories of energy transferred by rise the temperature of 20g of methanol by $40°\text{C}$ to be calculated.

Concept Introduction: Thermal energy is total kinetic energy that combined with motions and mass of particles in a sample of matter measured as heat energy.

Answer to Problem C18.3RE

Number of calories of energy transferred by rise the temperature of 20g of methanol by $40°\text{C}$ is 460 cal.

Explanation of Solution

Given mass of water (m) = 20g

Temperature change $\left(\Delta \text{T}\right)=40°\text{C}$

Specific heat of water is $0.575\text{cal}/\text{g}\cdot °\text{C}$

The equation of heat is as follows:

  $\text{H=mCΔT}$

Here H is heat, m is mass, C is specific heat and T is temperature.

Put the values in above equation is as follows:

  $\begin{array}{c}\text{H=20}\cancel{\text{g}}\times 0.575\frac{\text{cal}}{\text{g×}\cancel{\text{°C}}}\times 40\cancel{°\text{C}}\\ \text{=460cal}\end{array}$

Thus number of calories of energy transferred is 460 cal.