3.9 Composition of Compounds

Question 1

A ______ ______, in combination with the molar masses of its constituent elements, indicates the relative quantities of each ______ in a ______, which is extremely useful information.

Answer 1

A chemical formula, in combination with the molar masses of its constituent elements, indicates the relative quantities of each element in a compound, which is extremely useful information.

Question 2

How can we determine the mass of chlorine in a given mass of a CFC?

Answer 2

use the element’s mass percent composition for that compound. The mass percent composition or mass percent of an element is that element’s percentage of the compound’s total mass. We can calculate the mass percent of element X in a compound from the chemical formula as follows:

Question 3

The mass percent composition of an element in a compound is a ______ ______ between mass of the ______ and mass of the ______.

Answer 3

The mass percent composition of an element in a compound is a conversion factor between mass of the element and mass of the compound.

Question 4

______ ______ ______ is one way to understand how much chlorine is in a particular chlorofluorocarbon or, more generally, how much of a constituent element is present in a given mass of any compound.

Answer 4

Mass percent composition is one way to understand how much chlorine is in a particular chlorofluorocarbon or, more generally, how much of a constituent element is present in a given mass of any compound.

Question 5

Always remember that the chemical formula gives us a relationship between the amounts (in _____) of substances, not between the masses (in _____) of them.

Answer 5

Always remember that the chemical formula gives us a relationship between the amounts (in moles) of substances, not between the masses (in grams) of them.

Question 6

The general form for solving problems in which we are asked to find the mass of an element present in a given mass of a compound is

Mass compound -> moles compound -> moles element -> mass element
We use the atomic or molar mass to convert between mass and moles, and we use relationships inherent in the chemical to convert between moles and moles.

Answer 6

The general form for solving problems in which we are asked to find the mass of an element present in a given mass of a compound is

Mass compound -> moles compound -> moles element -> mass element
We use the atomic or molar mass to convert between mass and moles, and we use relationships inherent in the chemical to convert between moles and moles.