Question

Calculate the amount of heat needed to boil 21.3g of ethanol ( CH3CH2OH ), beginning from a temperature of 31.4°C . Be sure your answer has a unit symbol and the correct number of significant digits

please put the correct number of significant digits

Answer 1

Q = mc∆T

Q = heat energy (Joules, J), m = mass of a substance (g)

c = specific heat (units J/g∙^oC), ∆ is a symbol meaning "the change in"

∆T = change in temperature (^oC Celcius)

Specific heat of ethanol = 2.44 J/g∙^oC

Boiling point of ethanol =  78.37 °C

Heat of vaporization of ethanol = 38.6 Kj/Mol

Q = 21.3 x 2.44 J/g∙^oC x ( 78.37 °C- 31.4°C) + 21.3 x 38600 / 46.07

Q = 2441.124 Joules + 17486.32 Joules

Q = 20,287.44 Joules = 20.287 Kilo Joules

Hence 20.287 Kilo joules of heat is required to boil 21.3g of ethanol ( CH3CH2OH ), beginning from a temperature of 31.4°C