# Chemistry

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The combustion of benzoic acid releases 26.38kJ/g and is often used to calibrate a bomb calorimeter. the combustion of 1.045 g of benzoic acid caused the temperature of the calorimeter to rise by 5.985C. Useing the same calorimeter, a sample of 0.876g of octane (C8H18) was burned. The temperature increased by 8.518C. What is the molar enthalpy of the combustion of octane?

• Chemistry -

q = Ccal x delta T
26,380 J x 1.045g = Ccal x 5.985. Solve for Ccal.

q octane = Ccal x delta T. Solve for q which will be q/0.876g. You want q/mol. Take q/g x molar mass octane.

• Chemistry -

is delta T supposed to stay in Celsius or should i convert it to kelvin ?

• Chemistry -

It doesn't matter which you use. Since it is the difference you can see why.
20 C is 293 K
10 C is 283 K.
delta T in C is 20-10 = 10
delta T in K is 293-283 = 10

I always use C; converting to K is another step where I can make an error.

• Chemistry -

thank you so much!

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