How do you measure the enthalpy change of combustion of methane using a saucepan?

Answer 1

Enthalpy change of Methane.

• In this case your saucepan is the calorimeter, although i would use a metal that conducts better e.g. a copper cup
  
• measure the mass of the saucepan.
• Measure the mas of saucepan + the amount of water your using (this could be anything)
• Minus this number from the original mass of the calorimeter to give the total mass of the water.

• record the starting temperature of the water and decide when to stop the combustion (e.g. after a 10 degree rise 20, 30 ,40 etc.-normally this is done in kelvin by adding 273 to Celsius
  
• Measure the mass of the fuel your going to burn beforehand often youll need some sort of burner to do this.

• Light your fuel (methane) and put the saucepan over it (this will turn the pan black) make sure the flame has as little movement as possible - keep the pan directly over the heat.
• After the water has risen the set amount stop.
  
• Measure the mass of the methane left.(mass of fuel and burner before - mass of fuel and burner after)

• Using the formula energy transferred =cm deltaT where c is the heat capacity of water 4.18Jg-1K-1 m is the mass of water in grams and deltaT is the change in temperature, this will be the same in Kelvin and Celsius
• Calculate the energy transferred (deltaHc)

Extension

• The energy transferred above is for the mass of fuel burned we want the energy transferred for 1 mole of methane. (energy released per mole)
  

• Work out how many moles of methane you used. number of moles =mass in grams / the molar mass. (formula for methane is CH4 therefor molar mass= 12+(4*1)

• Now you need the energy released per mole of methane ( how many times does the number moles calculated divide into 1 molar of methane.
  

• For this you do (1/number of moles *the energy transferred) all divided by 1000 to give the energy per mole in kilo joules

NOTE: this answer will vary extremely from the true value of enthalpy levels of methane (840.4 KJ-1) as the true value is calculated using standard conditions: a specified temperature , standard atmospheric pressure and standard concentration of fuel.

NOTE: this experiment is just an extreme estimate of the true value as heat is not constantly distributed to the water energy is lost to the air and saucepan etc.

Answer 2

To measure the enthalpy change of combustion of methane using a saucepan, you can fill the saucepan with a known volume of water, record its initial temperature, ignite the methane gas, and place the saucepan on the flame. Measure the final temperature of the water after the combustion has ceased. The enthalpy change can be calculated using the mass of water, its specific heat capacity, and the temperature change.