# Composition of Substances and Solutions

## Vocabulary

### aqueous solution

solution in which the solvent is water

### atomic mass unit (amu)

mass of a single proton or neutron, equal to 1 gram per mole (g/mol), defined as one-twelfth the mass of a carbon-12 atom

number of particles of a substance per mole of that substance (in atoms, ions, or molecules), equal to $6.022\times{10}^{23}$

### concentrate

to let the solvent evaporate from a solution to increase its concentration

### concentration

amount of solute dissolved in a given volume of solvent

### crystallization

formation of a solid in which the particles form a highly organized structure

### dilute

to decrease a solution's concentration by adding more solvent to it

### dilution

less concentrated solution made by diluting a solution

### dissolve

to incorporate a substance into a liquid so as to form a solution

### formula mass

sum of the atomic weights of all atoms in a compound

### gas chromatography

analytical method in which a compound is vaporized and separated into its components

### mass percent

concentration of a solution expressed as the mass of the solute (in grams) divided by the mass of the solvent (in grams), multiplied by 100 to get a percentage

### mass/volume percent

concentration of a solution expressed as the mass of the solute (in grams) divided by the volume of the solution (in milliliters), multiplied by 100 to get a percentage

### molar mass

mass of one mole of the atoms, molecules, or formula units that make up a substance

### molarity (M)

number of moles of a solute dissolved in 1 liter of water

### mole

amount of a substance that contains as many particles as 12 grams of pure carbon-12, equal to equal to $6.022\times{10}^{23}$ (Avogadro's number) particles

### molecular mass

sum of the atomic weights of all atoms in a molecule

### parts per billion (ppb)

concentration expressed as mass of solute divided by mass of solution, multiplied by 109. For an aqueous solution, the parts per billion concentration is the mass (in micrograms, µg) of solute per liter of solution.

### parts per million (ppm)

concentration expressed as mass of solute divided by mass of solution, multiplied by 106. For an aqueous solution, the parts per million concentration is the mass (in milligrams, mg) of solute per liter of solution.

### percent composition

percentage by mass of each element present in a compound

### saturated solution

solution that contains the maximum amount of dissolved solute normally possible at a certain temperature

### solute

dissolved material in a solution

### solvent

substance that dissolves a material to form a solution

### supersaturated solution

solution that contains more than the maximum amount of dissolved solute normally possible at a certain temperature

### unsaturated solution

solution that contains less than the maximum amount of dissolved solute normally possible at a certain temperature

### volume percent

concentration of a solution expressed as the volume of the solute (in liters) divided by the volume of the solution (in liters), multiplied by 100 to get a percentage