Question

The diagram above represents the melting of H2O(s). A 2.00mole sample of H2O(s) at 0°C melted, producing H2O(l) at 0°C. Based on the diagram, which of the following best describes the amount of heat required for this process and the changes that took place at the molecular level?

Answer 1

Answer

Heat : 12 kJ,  to maintain hydrogen bonds

Further explanation

Given

A 2.00mole sample ⇒ n = 2 mol

H₂O(s) at 0°C melted, producing H₂O(l) at 0°C

Required

the amount of heat required

the changes that took place

Analysis

Conversion of mol to mass

Use formula of Heat  :

Q = mLf (melting/freezing)  

Lf=latent heat of fusion  (for water=334 J/g)

Solution

mass H₂O(MW=18 g/mol) :

$\tt mass=2\times 18=36~g$

Heat required :

$\tt Q=36\times 334=12024~J\approx 12~kJ$

The absorbed heat is used to maintain hydrogen bonds in water molecules (there are two hydrogen bonds per molecule)

Paraphrase

The amount of heat required : 12 kJ, and to maintain hydrogen bonds