Question

to warm 400.0g of water, 0.050 mol of ethanol (C2H5OH) is burned. The water warms from 24.6 Celcius to 65.5 Celcius. What is the heat of the reaction, and what is he Enthalpy change of the reaction on molar basis?

Answer 1

Temperature change of water 24.6⁰C to 65.5⁰C

T = 65.5 - 24.6 = 40.9⁰C

specific of water = 4.184 J/ g K

mass of water = 400 gm

q = mass of water   specific heat of H₂O_(l)      T

= 400   4.184   40.9

q = 68450.24 J = 68.45024 KJ

ethanol burning release heat therefore sign is negative

heat of reaction = -68.45024 KJ

0.050 mole theanol produce heat -68.45024 KJ then 1 mole ethanol produce heat = 1 - 68.45024 / 0.050

= -1369.0048 KJ/mol

enthalpy change = -1369.0048 KJ / mol