Burning of fuel in air is called combustion. CH4(g) + 2O2(g)  CO2 (g)+ 2H2O(l) a) Calculate the heat of reaction for the above reaction by using the following bond energies . (3 Marks) C-H single bond is 412 kJ , O=O double bond is 496 kJ, C=O double bond is 743 kJ, H-O single bond is 463 kJ b) Draw the energy profile diagram for the above reaction .On your diagram label the • Products, Reactants • enthalpy for the reaction • activation energy, Ea.

Explanation:

ΔH = ∑ BREAKING BONDS + ∑ GREATING NEW BONDS

  =( 4×412 + 2×496) _ ( 2×743  +  4×463)

 =  2640    KJ             _   3338 KJ       =  - 698 KJ/Mole

exothermic reaction

b) CH4  +  O2 are the reactant

    CO2   +H2O are the product

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.