Calorimetry

Any idea how to go about doing these questions?
In an experiment, 1.00g of hexane was completely burned in air. The heat evolved raised the temperature of 200g of water by 15.6°C. Use this data to
a) calculate the heat given off by the 1.00g of hexane
b) calculate the heat given off by hexane in kJ/g
c) calculate the moles of hexane burned
d) calculate the heat given off by hexane in kJ/mol
Any help would be really appreciated

Reply 1

help_101

Original post by theJoyfulGeek

The useful equation here is ΔQ = mcΔT
ΔQ is heat given off, m is mass of water, c is specific heat capacity of water (4.2J/g) and ΔT is temperature change.

It doesn't matter whether temperature is in °C or K here.

a) Q = 200 g * 4.2 J/g °C* 15.6°C = 13104 J.

b) Heat given off by burning 1g = 13.104 kJ / 1 g = 13.104 kJ/g or 13.1kJ/g to 3 sf.

c) Hexane is C6H14, and has a molar mass of 86g/mol. 1g / 86g/mol = 1/86 mol = 0.011627... mol or 0.0116 mol to 3sf.

d) 13.104kJ / 1/86 mol = 1126.944 kJ/mol or 1130 kJ/mol to 3sf.

I hope this helps!