(a)
Interpretation: The amount of heat lost or gained when 0.625 mol of NaOH (s) is dissolved in water needs to be determined.
Concept Introduction: A measurement in one set of units can be converted into another set of units using a conversion factor.
(a)
Explanation of Solution
The enthalpy of the dissolution reaction of NaOH is -41.6 kJ/mol. Thus, if 1 mol of NaOH is dissolved in water, 41.6 kJ of heat is lost.
The amount of heat lost for 0.625 mol of NaOH will be:
Thus, the amount of heat lost is 26 kJ. Here, the negative sign shows the loss of heat.
(b)
Interpretation: The amount of heat lost or gained when 1.17 mol of water freezes at
Concept Introduction: A measurement in one set of units can be converted into another set of units using a conversion factor.
(b)
Explanation of Solution
The enthalpy of the fusion of water is 6.01 kJ/mol. Thus, for 1 mol of water, 6.01 kJ of heat is required for fusion. To freeze water, the same amount of heat will be lost and the value will be -6.01 kJ.
The amount of heat lost for 1.17 mol of water will be:
Thus, the amount of heat lost is
(c)
Interpretation: The amount of heat lost or gained when 0.30 mol of
Concept Introduction: A measurement in one set of units can be converted into another set of units using a conversion factor.
(c)
Explanation of Solution
Heat of vaporization of
The amount of heat required for 0.30 mol of
Thus, the amount of heat gained is
(d)
Interpretation: The amount of heat lost or gained when 0.66 mol of the steam condenses at
Concept Introduction: A measurement in one set of units can be converted into another set of units using a conversion factor.
(d)
Explanation of Solution
The heat of condensation of steam is 40.8 kJ/mol. Thus, for 1 mol of water, 40.8 kJ of heat is gained.
The amount of heat required for 0.66 mol of steam will be:
Thus, the amount of heat gained is
Chapter 21 Solutions
Chemistry 2012 Student Edition (hard Cover) Grade 11
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