Basic Principles and Calculations in
Chemical Engineering (9th Edition,
2023 – Himmelblau & Riggs) | Complete
Solutions Manual PDF
Law of definite proportions - answer-In a pure compound, the elements are always present in
the same definite proportions by mass.
Significant figures - answer-Refer to them (sec 2.5) because they are important here.
Using decomposition data to illustrate the law of definite proportions - answer-If you have the
sample mass before decomposition and the mass of the constituents after decomposition then:
To find the percent of a component, divide the mass of the component in question by the total
mass of the sample, and multiply that by 100.
Percent (element) = mass of (element) obtained/ total sample mass x 100
**Don't forget about the rules for significant figures.
Other method of doing this:
Given two samples, mass of element 1/mass of element 2 = a ratio. Do this for for samples, and
compare the ratios. If the ratios are similar, then the
1
, **Refer to example 9.1
The ratio in which substances react - answer-is always the same.
*Refer to table 9.1 and figure 9.1 for illustration
Formula mass - answer-is the sum of the atomic masses of all atoms present in one formula unit
of a substance, expressed in atomic mass units.
The term "molecular mass" can be used interchangeably with "formula mass" when referring to
substances that contain discrete molecules, but cannot be used when talking about ionic
substances.
Significant figures and formula mass operational rules: - answer-Used throughout the remainder
of the text.
1) Atomic masses are rounded to the hundredths place for formula determinations.
2) If the atomic mass becomes a limiting factor (which is hardly ever the case), masses with
additional sig figs are found on the page next to the front inside cover. The first four only have 3
sig figs for example, and the sig figs are extended in the table in the aforementioned page.
3) When you are figuring out the formula mass treat all calculations are pure addition problems.
If you multiply amu by n, still treat it as an addition problem.
Percent by mass composition of a compound - answer-is the percent by mass of each element
present in the compound. For example, the percent composition by mass of water is 88.81%
oxygen and 11.19% hydrogen.
Percent by mass of an element in a compound - answer-is the number of grams of the element
present in 100 grams of the compound.
2
Chemical Engineering (9th Edition,
2023 – Himmelblau & Riggs) | Complete
Solutions Manual PDF
Law of definite proportions - answer-In a pure compound, the elements are always present in
the same definite proportions by mass.
Significant figures - answer-Refer to them (sec 2.5) because they are important here.
Using decomposition data to illustrate the law of definite proportions - answer-If you have the
sample mass before decomposition and the mass of the constituents after decomposition then:
To find the percent of a component, divide the mass of the component in question by the total
mass of the sample, and multiply that by 100.
Percent (element) = mass of (element) obtained/ total sample mass x 100
**Don't forget about the rules for significant figures.
Other method of doing this:
Given two samples, mass of element 1/mass of element 2 = a ratio. Do this for for samples, and
compare the ratios. If the ratios are similar, then the
1
, **Refer to example 9.1
The ratio in which substances react - answer-is always the same.
*Refer to table 9.1 and figure 9.1 for illustration
Formula mass - answer-is the sum of the atomic masses of all atoms present in one formula unit
of a substance, expressed in atomic mass units.
The term "molecular mass" can be used interchangeably with "formula mass" when referring to
substances that contain discrete molecules, but cannot be used when talking about ionic
substances.
Significant figures and formula mass operational rules: - answer-Used throughout the remainder
of the text.
1) Atomic masses are rounded to the hundredths place for formula determinations.
2) If the atomic mass becomes a limiting factor (which is hardly ever the case), masses with
additional sig figs are found on the page next to the front inside cover. The first four only have 3
sig figs for example, and the sig figs are extended in the table in the aforementioned page.
3) When you are figuring out the formula mass treat all calculations are pure addition problems.
If you multiply amu by n, still treat it as an addition problem.
Percent by mass composition of a compound - answer-is the percent by mass of each element
present in the compound. For example, the percent composition by mass of water is 88.81%
oxygen and 11.19% hydrogen.
Percent by mass of an element in a compound - answer-is the number of grams of the element
present in 100 grams of the compound.
2
