Concept explainers
A sample containing
Interpretation:
The mass percent of each compound in the sample is to be calculated.
Concept introduction:
The percent composition of an element by its mass in a compound can be calculated as:
Here, n represents the element’s number of atoms in the given molecule or compound.
The number of moles is defined as the ratio of mass to the molar mass.
Here,
Answer to Problem 137AP
Solution: The percent composition by mass of
Explanation of Solution
Given information: The percent composition by mass of
Let the mass of sample be
The mass of sodium is
The mass of oxygen is
The mass of chlorine is
The molar mass of sodium is
The molar mass of oxygen is
The molar mass of chlorine is
Calculate the number of moles of sodium as follows:
Substitute,
Calculate the number of moles of oxygen as follows:
Substitute,
Calculate the number of moles of chlorine as follows:
Substitute,
The element
The remaining value of
In
Equation (1) is as follows:
Equation (2) is as follows:
Multiply equation (1) by two and solve as follows:
Subtract equation (2) from equation (3) as follows:
The value of A can be calculated from value of B by using equation (1) as follows:
So, the number of moles of
The number of moles of
So, the number of moles of
The molar mass of
The molar mass of
The molar mass of
The mass of each compound in the sample can be calculated as:
Calculate the percent by mass of
Substitute,
Calculate the percent by mass of
Substitute,
Calculate the percent by mass of
Substitute,
Hence, the percent composition by mass of
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Chapter 3 Solutions
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