1) When hydrazine (N2H4) is burned in a 253-g brick container, the temperature of the brick increases by 5.13 degrees Celsius. Calculate the quantity of heat released in this raection. The specific heat of brick is 0.840 J/(gC).
2) A sample of coal is burned in a bomb calorimeter with a heat capacity of 4.62 KJ/C. The temperature in the calorimeter rises from 20.22 to 25.25 degrees celsius. Calculate the heat of the combustion reaction (qrxn) in KJ.
1) When hydrazine (N2H4) is burned in a 253-g brick container, the temperature of the brick increases by 5.13 degrees Celsius. Calculate the quantity of heat released in this raection. The specific heat of brick is 0.840 J/(gC).
2) A sample of coal is burned in a bomb calorimeter with a heat capacity of 4.62 KJ/C. The temperature in the calorimeter rises from 20.22 to 25.25 degrees celsius. Calculate the heat of the combustion reaction (qrxn) in KJ.
How do I solve these problems?
See one of your later posts.
To calculate the quantity of heat released in these reactions, we can use the formula:
q = m * c * ΔT
where:
q is the quantity of heat released or absorbed (in joules),
m is the mass of the substance (in grams),
c is the specific heat capacity of the substance (in J/(g°C)), and
ΔT is the change in temperature (in °C).
Let's solve the first question:
1) Given:
- Mass of the brick container (m): 253 g
- Specific heat capacity of the brick (c): 0.840 J/(g°C)
- Change in temperature (ΔT): 5.13 °C
Using the formula:
q = m * c * ΔT
q = 253 g * 0.840 J/(g°C) * 5.13 °C
q ≈ 1091.26 J
Therefore, the quantity of heat released in this reaction is approximately 1091.26 J.
Now let's move to the second question:
2) Given:
- Heat capacity of the bomb calorimeter (C): 4.62 kJ/°C (kilojoules per degree Celsius)
- Change in temperature (ΔT): 25.25 °C - 20.22 °C = 5.03 °C
Note that the heat capacity of the calorimeter is given in kilojoules (kJ), so we need to convert the change in temperature to kilojoules as well.
Using the formula:
q = C * ΔT
q = 4.62 kJ/°C * 5.03 °C
q ≈ 23.213 kJ
Therefore, the heat of the combustion reaction (qrxn) is approximately 23.213 kJ.