[Physics] How do we measured specific heat capacity without knowing heat or other material heat capacity

thermodynamics

How can we find specific heat capacity without using heat, $$ c= \dfrac{\delta Q}{m \,\delta T}$$ Calorimeter $$ c_1\cdot m_1\cdot \delta T_1 =c_2\cdot m_2 \cdot \delta T_2 $$ In this formula we can measure mass by balance and temperature with thermometer. But we need one specific heat either $c_1$ or $c_2$ to calculate other material heat capacity.

The question arise how do we know heat capacity of the first material to use as reference, because we can not calculate heat & specific heat capacity directly. How the first time we calculate heat capacity.

Is there any reference material heat capacity to use as relative. Or any statistical calculation or any other?

Best Answer

$cm\delta T=\delta Q$ , that's pretty much self evident , for the reference material the $\Delta Q$ is calculated in isolation , maybe with a burner or something , by heating it , Now you already have the thermometer and from the amount of fuel exhausted you know the heat change for say in the temperature change $\Delta T$ . Now if we have a same temperature change in your two body setting then you already know the heat change in one of the body from the above experiment .So in the second equation you've put $c_1m_1\delta T$ is known because its equal to $\delta Q$ , you see there is no variable except $c_2$ now.
How is the calorific value of fuel calculated ?
The fuel is put in a bomb calorimeter , upon burning the fuel releases heat and heats up the surrounding water , of which we calculate the temperature change.The unit of heat is defined with respect to water (calorie units) as you must be knowing.Since you know the temperature change , of water , you directly know the number of calories of heat released by fuel(calorific value) , problem solved , now you can proceed with the first paragraph.

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