| Why can it be assumed that that the heat of the reaction is the same thing as the heat as one part of the components of the reaction
C3H8(g)+5O2(g) yields 3CO2(g)+4H20
what mass of C3H3 is necessary to heat 1.8L of water from 25 to 100 degree Celsius ? assume only 15% of heat emitted from combustion reaction to heat up the water

I understand that (1800ml)(4.18J/g Celsius)(75) to find heat of water
I don't understand what to do next

Question

| Why can it be assumed that that the heat of the reaction is the same thing as the heat as one part of the components of the reaction
C3H8(g)+5O2(g) yields 3CO2(g)+4H20
what mass of C3H3 is necessary to heat 1.8L of water from 25 to 100 degree Celsius ? assume only 15% of heat emitted from combustion reaction to heat up the water

I understand that (1800ml)(4.18J/g Celsius)(75) to find heat of water
I don't understand what to do next