A 1.435g of Naphthalene (C10H8) was burned in Constant Volume Bomb Calorimeter. Consequently, temperature of the water rose from 20.17 degrees cerisious to 25.84 degrees cerisious. If the mass of water surrounded the Calorimeter was exactly 2.0×10^3 Kg and the heat capacity of the Bob Calorimeter was was 1.80 Kj/degree cerisious, calculate the molar heat of reaction (combustion) in KJ of Naphthalene.
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To calculate the molar heat of combustion of Naphthalene (C10H8) in kilojoules per mole (kJ/mol), we need to follow these steps:
Step 1: Calculate the heat absorbed by the water
The heat absorbed by the water can be calculated using the formula:
q = mcΔT
where:
q = heat absorbed by the water (in Joules)
m = mass of water (in kilograms)
c = specific heat capacity of water (4.18 J/g·°C or 4.18 kJ/kg·°C)
ΔT = change in temperature of the water (in degrees Celsius)
First, let's convert the mass of water into grams.
mass of water = 2.0 × 10^3 kg × 1000 g/kg
mass of water = 2.0 × 10^6 g
Now, we can calculate the heat absorbed by the water:
q = (2.0 × 10^6 g) × (4.18 kJ/kg·°C) × (25.84°C - 20.17°C)
Step 2: Calculate the heat absorbed by the bomb calorimeter
The heat absorbed by the bomb calorimeter can be calculated using the formula:
q = CΔT
where:
q = heat absorbed by the bomb calorimeter (in Joules)
C = heat capacity of the bomb calorimeter (1.80 kJ/°C)
ΔT = change in temperature of the bomb calorimeter (in degrees Celsius)
ΔT = 25.84°C - 20.17°C
Now, we can calculate the heat absorbed by the bomb calorimeter:
q = (1.80 kJ/°C) × ΔT
Step 3: Calculate the total heat released by the combustion of Naphthalene
To calculate the total heat released by the combustion of Naphthalene, we need to sum up the heat absorbed by the water and the heat absorbed by the bomb calorimeter:
q_total = q_water + q_bomb_calorimeter
Step 4: Calculate the moles of Naphthalene
The moles of Naphthalene can be calculated using its molar mass (Mr). The molar mass of Naphthalene (C10H8) = 128.18 g/mol.
moles of Naphthalene = mass of Naphthalene (g) / molar mass of Naphthalene (g/mol)
Step 5: Calculate the molar heat of combustion of Naphthalene
The molar heat of combustion of Naphthalene can be calculated using the formula:
Molar heat of combustion (ΔH) = q_total / moles of Naphthalene
Finally, convert the result from Joules to kilojoules by dividing by 1000.
That's it! Follow these steps to calculate the molar heat of combustion of Naphthalene (C10H8) in kilojoules per mole.
I have no idea what a degree "cerisious" is but at least you're consistent. I assume you meant "Celsius".
q = mcdT + Ccal*dT
q = 2,000,000 x 4.184 J/C*K x (25.84-20.17) + 1800 J/C x (25.84-20.17).
That gives you q for 1.435 g naphthalene. Convert that to q for the molar mass of naphthalene in grams.
Post your work if you get stuck.