1. Mass/Mass (grams solute / 100 grams water)
| mass solute | = | X | OR | mass solute | x100 |
| mass water | 100 | mass water |
2. Percent (%)
| mass solute | = | X | OR | mass solute | x 100 |
| mass solution | 100 | mass solution |
3. Parts Per Million (ppm)
| mass solute | = | X | OR | mass solute | x 1,000,000 |
| mass solution | 100,000,000 | mass solution |
4. Parts Per Billion (ppb)
| mass solute | = | X | OR | mass solute | x 1,000,000,000 |
| mass solution | 1,000,000,000 | mass solution |
NOTE: For ppm and ppb, the amount of solute is so tiny that the mass of the solution and the mass of water can be considered the same. If the mass of solute makes a difference in the answer, then you should use the percent method.