Concept explainers
A 12-oz (355-mL) Pepsi contains 38.9 mg caffeine (molar mass = 194.2 g/mol). Assume that the Pepsi, mainly water, has a density of 1.01 g/mL. For such a Pepsi, calculate: (a) its caffeine concentration in ppm; (b) its molarity of caffeine; and (c) the molality of caffeine.
(a)
Interpretation:
The caffeine concentration in
Answer to Problem 56QRT
The caffeine concentration in
Explanation of Solution
Given data as follows: Molar mass is
As known,
Conversion of water from
Conversion of
Therefore, caffeine concentration in
(b)
Interpretation:
The molarity of caffeine has to be calculated.
Concept introduction:
Molarity: Dividing moles of solute by the volume of solution in Liter.
Answer to Problem 56QRT
The caffeine concentration in
Explanation of Solution
Given data as follows: Molar mass is
Conversion of mass into mole as,
Conversion of
Molarity of solution is calculated as,
Therefore, molarity of caffeine was
(c)
Interpretation:
The molality of caffeine has to be calculated.
Concept introduction:
Molality: Dividing the moles of solute by the mass of solvent in kg.
Answer to Problem 56QRT
The molality of caffeine was
Explanation of Solution
Given data as follows: Molar mass is
Conversion of mass into mole as,
Conversion of
Conversion of water from
Molality of solution is calculated as,
Therefore, molality of caffeine was
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Chapter 13 Solutions
Chemistry: The Molecular Science
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