Question

The latent heats of fusion in \[J{g^{ - 1}}\] of five substances (mol. mass=18); b (mol. mass=20); c (mol. mass=30); d (mol. mass=60); and e (mol. mass=30) are respectively 80, 45, 90, 45, 45. Which of the following pairs has the same value of \[\Delta {H_{fusion}}\] ?
A) a, c
B) b, e
C) d, e
D) c, d

Answer 1

Hint: Latent heat of fusion is the enthalpy change of any amount of substance when it melts. When the heat of fusion is referenced to a unit of mass, it is called the specific heat of fusion and the molar heat of fusion refers to the enthalpy change per amount of substance in moles.

Complete answer:
\[\Delta {H_{fusion}}\] is also called latent heat of fusion or enthalpy of fusion. Enthalpy of fusion of a substance is the change in its enthalpy resulting from providing energy or heat to a specific quantity of a substance to change its state from solid to liquid at constant pressure. The heat of solidification that is the conversion from liquid to solid is equal and opposite.
The formula for calculating energy needed is given as
Heat transferred= Mass \[ \times \] specific latent heat capacity
\[\Delta {H_{fusion}}\] for given compounds is as given below:
For substance a,
\[a = 18 \times 80 = 1440J\]
For substance b,
\[b = 20 \times 45 = 900J\]
For substance c,
\[c = 30 \times 90 = 2700J\]
For substance d,
\[d = 60 \times 45 = 2700J\]
For substance e,
\[e = 30 \times 45 = 1350J\]
Here we can see that c and d have the same value of \[\Delta {H_{fusion}}\] .

Therefore, the correct answer is option D.

Note: The question was simple but Heat of fusion is an important topic to determine information about any reaction like it is exothermic or endothermic and how much heat is released and many more.