Answer:
(a)
From surrounding to wax
(b)
Q = 2.62 KJ
(c)
Density of a substance is defined as the no. of particles of the substance, that occur in a unit volume. So, when the substance melts, the inter-molecular attractive forces and bonds between molecules or atoms are weakened. This, increases the distance between the molecules or atoms. Hence, the no. of particles in a unit volume is decreased. As, a result of this, the density of the substance also decreases.
Explanation:
(a)
During the melting process, the solid material or substance requires energy, in order to break the bonds between its molecules or atoms.
<u>Therefore, while the wax is melting, the net flow of thermal energy is from surrounding to the wax.</u>
<u></u>
(b)
The amount of energy required to melt solid paraffin wax is given by the formula:
Q = nC
where,
Q = amount of energy
C = Molar Heat of Fusion = 48.78 KJ/mol
n = No. of Moles = Mass in gram/Molar Mass = (15.2 g)/(282.62 g/mol)
n = 0.0538 mol
Therefore,
Q = (0.0538 mol)(48.78 KJ/mol)
<u>Q = 2.62 KJ</u>
<u></u>
(c)
Density of a substance is defined as the no. of particles of the substance, that occur in a unit volume. So, when the substance melts, the inter-molecular attractive forces and bonds between molecules or atoms are weakened. This, increases the distance between the molecules or atoms. Hence, the no. of particles in a unit volume is decreased. As, a result of this, the density of the substance also decreases.
