Concentration

Solution Concentration

Concentration = quantity of solute quantity of solution

There are 3 basic ways to express concentration:1) Percentages2) Ppm and ppb (used for very low

concentration)3) Molar concentrations

1. Percent Concentration

O % concentration can be in O % Volume/VolumeO % Weight/WeightO % Weight/Volume

Percent V/V Concentration

% V/V = volume of solute (mL or L) x 100%

volume of solution (mL or L)

Example:: 140 mL of acetic acid is present in 500. mL of water. What is the percentage by volume concentration of acetic acid?

Percent W/W Concentration

% W/W = weight of solute (g or Kg) x 100% weight of solution (g or Kg)

Example: What is the % W/W if 8.0 g copper is added to enough zinc to produce 100. g of an alloy?

Percent W/V Concentration

% W/V = weight of solute (g) x 100% volume of solution (mL)

•Can use g/mL or Kg/L

Example: If 250 g of sodium chloride is present in 3.0 L of solution, what I the percentage weight by volume of sodium chloride?

2. Very Low Concentrations

O Expressed in parts per million (ppm) or part per billion (ppb)

O A type of W/W or W/V concentration O Chlorine concentration in a swimming pool

may be expressed as ppm1 mg/L or 1 mg/Kg = 1ppm1 mg /1000 L or 1 mg/1000 Kg = 1ppb

Example: 1) Convert 45 ppm to g/L, 45 ppb to g/L.2) Convert 3.75 mg in 50 mL to ppm.

Molar Concentration

Molar Concentration = amount of solute (in moles)

volume of solution (in L)

C = n/V

Units are mol/L or M or Molar

Molar Concentration

Examples:1) If a reaction produced 0.186 mol of

sodium hydroxide in 0.250 L of solution, calculate the molar concentration of sodium hydroxide.

2) 64 g of oxygen gas (O2) are dissolved in 100. L of air. What is the concentration?