Methylhydrazone, CH 6 N 2 , is commonly used as rocket fuel. When 3.71g of methy
ID: 507296 • Letter: M
Question
Methylhydrazone, CH6N2, is commonly used as rocket fuel. When 3.71g of methylhydrazine is combusted in a “bomb” calorimeter containing 1500g of water, the temperature rose from 25.0oC to 39.5oC. If the reaction produces 1.30 x 103kJ/mol CH6N2, what is the heat capacity of the calorimeter? Specific heat capacity of water is 4.184J/g oC.
CH6N2(l) + 5 O2(g) ----> 2 N2(g) + 2 CO2(g) + 6 H2O(l)
a) 500J/oC b) 950J/oC c) 1500J/oC d) 3200J/oC e) 5400J/oC
I found, From reaction:104650 J , To water: 91002 J. The outside is assumed to be 0. But i dont know what to do for the calorimeter
Explanation / Answer
Ans. The heat released during combustion of fuel is absorbed by-
I. Water filled in water, and
II. The Calorimeter. The inner surface of the ignition chamber is generally made up of metal/ alloy (say, stainless steel). So, the calorimeter material also absorbs some amount of heat to reach the thermal equilibrium.
So,
Amount of heat absorbed by calorimeter =
(Total energy released from combustion – Heat absorbed by water)
= 1046500 J – 91002 J
= 955498 J
Amount of heat gained by Calorimeter while temperature increases is given by-
Q = C x dT
Where, C = heat capacity of calorimeter
Or, 955498 J = C x (14.50C)
Or, C = 955498 J / (14.50C) = 65896.41 J/0C
Thus, heat capacity of calorimeter = 65896.41 J/0C = 65.89 kJ/0C
Note: 1. From the available data, heat capacity of calorimeter = 65.89 kJ/0C It is a very high value for the heat capacity of a calorimeter.
2. Please check if there is any other information mission from the question that could alter the values. Or, re-check if all values in the question are put correctly. Or, the options provided are correct ?
3. If any variation is found, please do calculations accordingly. The values [From reaction:104650 J , To water: 91002 J ] have been calculated correctly by you.