Concentrations of Solutions Concentration measures exactly how much solute is in a certain amount of solvent. Concentration measures exactly how much solute is in a certain amount of solvent. Parts per Million (ppm or mg/L) Parts per Million (ppm or mg/L) Parts per Billion (ppb) Parts per Billion (ppb)

Acceptable lead levels in drinking water [

Concentrations of Solutions If chlorine levels are 3.0 ppm in drinking water what does this mean in terms of grams of water? If chlorine levels are 3.0 ppm in drinking water what does this mean in terms of grams of water? 1 million H 2 O molec.1 mole H 2 O 6.02 x molec x moles H 2 O

= x g H 2 O 18.0 g H 2 O 1 mol H 2 O Or… 3 chlorine atoms in every g of water!

Concentrations of Solutions For larger concentrations, Molarity (M) can be used: For larger concentrations, Molarity (M) can be used:

Concentrations of Solutions Example: Example: What is the molarity of a solution where 10.0 g of H 2 SO 4 is mixed in mL of water? What is the molarity of a solution where 10.0 g of H 2 SO 4 is mixed in mL of water?

= mol = 1.02 mol/L 10.0 g H 2 SO 4 1 mol H 2 SO g H 2 SO mol L

Concentrations of Solutions When only the mass of the solution can be measured, molality (m) can be used: When only the mass of the solution can be measured, molality (m) can be used:

Concentrations of Solutions Example: Example: What is the molality of a solution where 87.8 g of NaCl is mixed with g of ice (H 2 O)? What is the molality of a solution where 87.8 g of NaCl is mixed with g of ice (H 2 O)?

= 1.50 mol = 10.0 mol/kg 87.8 g NaCl 1 mol NaCl 58.5 g NaCl 1.50 mol kg