I am currently doing an experiment where I am burning methanol to test for the heat of combustion. To test this, I am heating 100g of water and raising it by 20 degrees Celsius before extinguishing the flame.
Using $q=m c \Delta T$, I have calculated that I need 8.4 kJ of energy to heat 100g of water by 20 degrees Celsius. The initial amount of methanol was 3.96g, and the remaining after combustion was 3.59g. This means that 0.37g of methanol was used in the process. The heat of combustion was -726 kJ/mol.
I have forgotten to time my experiment to see how long it took for this to occur. I was wondering if there is a formula or relationship that I can use to calculate this so that I don't have to do the experiment all over again.