
To find:
a) Write a balanced chemical equation for the reaction that takes place in a cup.
b) Determine if
c) Calculate the enthalpy change per mole of

Answer to Problem 9.107QA
Solution:
a) Balanced equation for the reaction of
b) Both
c) Enthalpy change per mole of
Explanation of Solution
1) Concept:
We know the concentrations, volumes, densities, and initial and final temperatures of two solutions – a strong acid and a strong base. We are asked to calculate the value of
The density of both aqueous solutions is nearly the same as that of water, which confirms that they are dilute solutions with heat capacities that are essentially the same as that of water. Therefore, equation for
2) Formula:
i)
where
ii)
where,
iii)
iv) The relation between enthalpy change and energy transferred is
where,
v)
3) Given:
i) Molarity of
ii) Volume of
iii) Molarity of
iv) Volume of
v) Initial temperature =
vi) Final temperature =
vii) Density of mixed solution is
viii) The specific heat of the mixed solution is
4) Calculation:
a) Writing the balanced equation for the neutralization reaction between
Taking an inventory of atoms on both sides of reaction,
Add coefficient 2 in front of
This is a balanced equation.
b) Limiting reactant:
Moles of
Convert volume in
Calculate the moles of
Convert volume in
Mole ratio of
i.e., for the reaction
c) Calculating enthalpy change per mole of
Total volume of solution =
Calculating the mass of solution using density:
Calculating the energy required for the reaction:
Since no heat is lost to surroundings,
Conclusion:
The limiting reactant is determined using stoichiometry of the reaction. Then from the energy transferred, enthalpy change per mole of water is calculated.
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Chapter 9 Solutions
Chemistry: An Atoms-Focused Approach
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