Chapter 15.1, Problem 5PP

Interpretation Introduction

Interpretation:

The specific heat of an unknown substance is to be calculated for given amount and rise in temperature and the substance is to be identified

Concept introduction:

Specific heat is defined as quantity of heat required to raise the temperature of one gram substance by one Kelvin. It is represented by ‘c’.

Answer to Problem 5PP

The specific heat of substance is $2.45J/g-°C$

Table shows the substance is ethanol.

Explanation of Solution

The quantity of heat required can be calculated by using formula:

$\begin{array}{l}q=mc\Delta T\\ whereqisquantityofheatabsorbed\\ m=givenmass\\ \Delta T=riseintemperature\\ cisspecificheat\\ \therefore c=\frac{q}{m\Delta T}\end{array}$

Given data:

$\begin{array}{l}m=155g\\ \Delta T=40-25\\ =15°C\\ q=5696J\end{array}$

Substituting the values in formula:

$\begin{array}{c}c=\frac{q}{m\Delta T}\\ =\frac{5696}{155\times 15}\\ =2.45J/g-°C\end{array}$

Table shows that ethanol has this value of specific heat.

Conclusion

Thus specific heat of substance is $2.45J/g-°C$

Table shows the substance is ethanol.