Question

A sample of hexane (C6H14) has a mass of 0.580 g. The sample is burned in a bomb calorimeter that has a mass of 1.900 kg and a specific heat of 3.21 J/giK. What amount of heat is produced during the combustion of hexane if the temperature of the calorimeter increases by 4.542 K?

Answer 1

Use the formula, Q= mcT

Q= heat
m= mass= 1.900Kg= 1.900 x 10^3 grams
c= specific heat= 3.21
T= 4.542 K

Q= (1.900 x10^3g)(3.21)(4.542K)= 14.6 Joules.

Answer 2

Answer : The amount of heat produced during the combustion of hexane per mole is 4109.79 kJ/mole.

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

Formula used :

`Q=m* c* \Delta T`

where,

Q = heat absorb = ?

m = mass of calorimeter = 1.900 kg = 1900 g

c = specific heat of calorimeter =
`3.21J/g.K`

`\Delta T` = change in temperature = 4.542 K

Now put all the given value in the above formula, we get:

`Q=1900g* 3.21J/g.K* 4.542K`

`Q=27701.658J=27.70kJ`

Now we have to calculate the moles of hexane.

`\text{Moles of }C_6H_(14)=\frac{Mass of }C_6H_(14)}{Molar mass of }C_6H_(14)=(0.580g)/(86.18g/mole)=0.00674mole`

Now we have to calculate the heat produced during the combustion of hexane per mole.

`\text{Heat produced}=(27.70kJ)/(0.00674mole)=4109.79kJ/mole`

Therefore, the amount of heat produced during the combustion of hexane per mole is 4109.79 kJ/mole.