Chapter U5, Problem 12STP

Interpretation Introduction

Interpretation:

The amount of energy transferred to the water from octane needs to be determined.

Concept introduction:

The amount of energy transferred in a system can be calculated as follows:

$q=mc\Delta T$

Here, m is mass, c is specific heat capacity and $\Delta T$ is change in temperature.

Answer to Problem 12STP

The correct option is (B).

Explanation of Solution

The specific heat capacity of water is $4.2{\text{ J/g }}^{\text{o}}\text{C}$

The mass of octane is 2.6 g and volume of water is 926 mL. The change in temperature takes place from $22{}^{\text{o}}\text{C}$ to $54{}^{\text{o}}\text{C}$.

The energy transferred can be calculated as follows:

$q=mc\Delta T$

Putting the values,

$\begin{array}{l}q=\left(2.6\text{ g}\right)\left(4.2{\text{ J/g }}^{\text{o}}\text{C}\right)\left(54-22\right){}^{\text{o}}\text{C}\\ =349.44\text{ J}\left(\frac{{10}^{-3}\text{ kJ}}{1\text{ J}}\right)=0.35\text{ kJ}\end{array}$

Thus, the amount of heat transferred is 0.35 kJ.

Conclusion

Therefore, the correct option is (B).