Question

Calculate the amount of heat needed to melt 148. g of solid octane (C8H18 ) and bring it to a temperature of 117.8 degrees c. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.

Answer 1

Answer:

The amount of heat is 84.4894kJ

Explanation:

Given data:

mass of octane=148g

The moles of octane is:

$n_{octane} =148g*\frac{1mol}{114.23g} =1.2956moles$

The melting point is=-56.82°C

ΔHfus=20.73kJ/mol

The heat of fusion is:

$Q_{fus} =n_{octane} *delta-H_{fus} =1.2956*20.73=26.8578kJ$

The heat to bring the octane to a temperature of 117.8°C is:

$Q_{2} =mCp(117.8-(56.82))=148*2.23*(117.8+56.82)=57631.5848J=57.6316kJ$

The total heat in the process is:

Qtotal=Qfus+Q₂=26.8578+57.6316=84.4894kJ