Question

Express latent heat of fusion and latent heat of vaporizations of water in j/g, kj/g and in kj/mol ?


I want solution in Mathematical

Answer 1

The molar latent heat of fusion, which is an alternative name given to the enthalpy of fusion, tells you how much heat is required in order to convert a specific amount of a given substance, either a gram or a mole, from solid at its melting point to liquid at its melting point.

Ice is said to have a molar enthalpy of fusion equal to

Δ

H

fus

=

6.0 kJ mol

−

1

This means that in order to melt

1

mole of ice at its normal melting point of

0

∘

C

, you must supply it with

6.0 kJ

of heat.

Now, your sample of ice has a mass of

36 g

, so the first thing to do here is to convert it to moles by using the molar mass of water

36

g

⋅

1 mole H

2

O

18.015

g

=

1.998 moles H

2

O

You can now use the molar enthalpy of fusion as a conversion factor to help you figure out how much heat must be supplied to your sample

1.998

moles ice

⋅

6.0 kJ

1

mole ice

=

12 kJ

−−−−−

The answer is rounded to two sig figs.

Answer 2

$\bf\huge\textbf{\underline{\underline{According\:to\:the\:Question}}}$  

Latent heat of fusion of water = 80 cal/g

= 80 × 4.184 j/g (1 cal = 4.184 j)

= 334.72 j/g

=0.335 kj/j

= 334.72 kj/kg

= 0.335 × 18 kg/mol (Molar mass of Water = 18)

$\bf\huge\bf\huge{\boxed{\bigstar{{6.03\: kj/mol}}}}$

Latent heat of vaporization of water = 540 cal/g

= 540 × 4.184 j/g

= 2259.3 j/g

= 2.2593 kg/g

= 2259.3 kj/kg

= 2.259 × 18 kj/mol

$\bf\huge\bf\huge{\boxed{\bigstar{{40.662\: kg/mol}}}}$

Additional Information = The value which is expressed in kj/mol are known as Molar heat of fusion and also Molar heat of Vaporisation