[SOS]

When a 1.000 g sample of the rocket fuel hydrazine, N2H4, is burned in a bomb calorimeter which contains 1200 g of water, the temperature rises from 24.62°C to 28.16°C. If the C for the bomb is 840 J/°C, calculate the heat of
combustion of hydrazine in kJ/mol.

---------- Let me know if I did this correctly or not-----

Heres what I did:

Bomb Calorimeter = c Delta T

= (850J/°C)(3.54°C) = 3009J = 3.009 kJ (surrounding)

Water = m x c x Delta T

= (1200g)(840J/°C)(3.54°C) = 3568320 J = 3568.32 kJ (surrounding)

3.009 kJ + 3568.32 kJ = 3571.329 kJ (surrounding)

Since the bomb calorimeter and water are surrounding and the energy is positive, the system should be negative. The question wants the heat of combustion for the hydrazine in kJ/mol I divided..

-3571.329/0.3125mol = -11427.2 kJ/mol.

Is this correct?

[Borek]

Logic behind looks OK, I have not checked numbers.

[DrCMS]

When a 1.000 g sample of the rocket fuel hydrazine, N2H4, is burned in a bomb calorimeter which contains 1200 g of water, the temperature rises from 24.62°C to 28.16°C. If the C for the bomb is 840 J/°C, calculate the heat of
combustion of hydrazine in kJ/mol.

---------- Let me know if I did this correctly or not-----

Heres what I did:

Bomb Calorimeter = c Delta T

= (850J/°C)(3.54°C) = 3009J = 3.009 kJ (surrounding)

Water = m x c x Delta T

= (1200g)(840J/°C)(3.54°C) = 3568320 J = 3568.32 kJ (surrounding)

3.009 kJ + 3568.32 kJ = 3571.329 kJ (surrounding)

Since the bomb calorimeter and water are surrounding and the energy is positive, the system should be negative. The question wants the heat of combustion for the hydrazine in kJ/mol I divided..

-3571.329/0.3125mol = -11427.2 kJ/mol.

Is this correct?

No

Logic behind looks OK, I have not checked numbers.

Sort of but the numbers are wrong.

What is the specific heat capacity of water?   If you use the correct value and recalculate you should come up with the correct answer.

[SOS]

When a 1.000 g sample of the rocket fuel hydrazine, N2H4, is burned in a bomb calorimeter which contains 1200 g of water, the temperature rises from 24.62°C to 28.16°C. If the C for the bomb is 840 J/°C, calculate the heat of
combustion of hydrazine in kJ/mol.

---------- Let me know if I did this correctly or not-----

Heres what I did:

Bomb Calorimeter = c Delta T

= (850J/°C)(3.54°C) = 3009J = 3.009 kJ (surrounding)

Water = m x c x Delta T

= (1200g)(840J/°C)(3.54°C) = 3568320 J = 3568.32 kJ (surrounding)

3.009 kJ + 3568.32 kJ = 3571.329 kJ (surrounding)

Since the bomb calorimeter and water are surrounding and the energy is positive, the system should be negative. The question wants the heat of combustion for the hydrazine in kJ/mol I divided..

-3571.329/0.3125mol = -11427.2 kJ/mol.

Is this correct?

No

Logic behind looks OK, I have not checked numbers.

Sort of but the numbers are wrong.

What is the specific heat capacity of water?   If you use the correct value and recalculate you should come up with the correct answer.

Oh you're right. For Water the specific heat is 4.18. I used 840J.