# Concentrations of Solutions Concentration measures exactly how much solute is in a certain amount of solvent. Concentration measures exactly how much solute.

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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)

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 10 23 molec. 1.66 x 10 -18 moles H 2 O

= 2.988 x 10 -17 g H 2 O 18.0 g H 2 O 1 mol H 2 O Or… 3 chlorine atoms in every 0.000000000000000002988 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 100.0 mL of water? What is the molarity of a solution where 10.0 g of H 2 SO 4 is mixed in 100.0 mL of water?

= 0.102 mol = 1.02 mol/L 10.0 g H 2 SO 4 1 mol H 2 SO 4 98.1 g H 2 SO 4 0.102 mol 0.1000 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 150.0 g of ice (H 2 O)? What is the molality of a solution where 87.8 g of NaCl is mixed with 150.0 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 0.150 kg

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