Elements in the compound

masses of the elements in the compound, taking into account the number of atoms of each element (which is indicated by its subscript).

Refer to Example 4.3 on page 111. Explain how to calculate the number of atoms in a given mass of an element.

Use the atomic mass as the conversion factor to convert from mass to moles, and then use Avogadro's number as the conversion factor to convert from moles to atoms.

Explain how to use Avogadro’s number to calculate the number of moles in a given number of atoms of an element.

Divide the number of atoms of an element by Avogadro's number to get the number of moles of the element.

Refer to Example 4.7 on page 116. Explain how to calculate the mass percentage of each element in a compound.

Divide the mass of the element present in 1 mole of the compound by the total mass of 1 mole of the compound.

Describe how combustion analysis is used to derive the percentage composition of a compound.

The sample is burned in the presence of oxygen. The products are collected by absorption using appropriate materials, and their amounts are determined by measuring the increase in masses of the absorbing materials.

Refer to Example 4.11 on page 122. Explain how to calculate the empirical formula for a compound from mass percentages.

Assume that you have a 100.00 g sample of the compound. Use this to convert the mass of each substance to moles. Because the empirical formula is a mole ratio, divide each mole value by the smallest number of moles present. This ratio gives the empirical formula.

Refer to Example 4.13 on page 127. Explain how to calculate the molecular formula for a compound from the empirical formula and the molecular mass.

To find the molecular formula, divide the molar mass of the compound by the empirical formula mass. Multiply the resulting number by each of the subscripts in the empirical formula to give the molecular formula.

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