Formulas Specifying Proportional parts

Sometimes the formula of a pharmaceutical product lists ingredients in parts rather than measures of weight or volume. Factor method can be used to reduce or enlarge formulas that express metric quantities in weight or volume.

Solved Problem:

From the following formula, calculate the quantity of each ingredient required to make 1000 g of powder.

Ingredient
Calcium carbonate 5 parts
Magnesium oxide 1 part
Sodium bicarbonate 4 parts
Bismuth subcarbonate 3 parts

Approach: Use the equation to determine the factor. Multiply each ingredient with the factor.

$$Factor = {1000 \ g (desired) \over 5+1+4+3(formula \ given) } = {1000\ g \over 13\ parts}=76.923\ grams/part $$

Using the factor 2.5, quantity of each ingredient can be determine.

Ingredient
Calcium carbonate 5 parts X 76.923 = 384.62 g
Magnesium oxide 1 part X 76.923 = 76.923 g
Sodium bicarbonate 4 parts X 76.923 = 307.69 g
Bismuth subcarbonate 3 parts X 76.923 = 230.77 g

Answer: Calcium carbonate 384.62 g; Magnesium oxide 76.923 g, Sodium bicarbonate 307.69 g, Bismuth subcarbonate 230.77 g.