Solutions Concentrations of Solutions

Solute versus Solvent Solute – the substance (usually a solid, sometime a liquid) being dissolved or broken down by the solvent Solute – the substance (usually a solid, sometime a liquid) being dissolved or broken down by the solvent Solvent - the substance (usually a liquid, sometimes can be a gas) that dissolves or breaks down the solute Solvent - the substance (usually a liquid, sometimes can be a gas) that dissolves or breaks down the solute Water is the universal solvent. Why??? Water is the universal solvent. Why???

Molarity From your own experience, what does “concentration” mean? From your own experience, what does “concentration” mean?

Molarity Concentration: Concentration: Used to quantitatively tell us how much solute per solvent we have in a given solution Used to quantitatively tell us how much solute per solvent we have in a given solution Dilute solution: Dilute solution: Only has a little solute Only has a little solute Concentrated solution: Concentrated solution: Has a lot of solute Has a lot of solute

Molarity Molarity: Molarity: A form of expressing concentration in which 1 molar = 1 mole of solute per 1 liter of solution A form of expressing concentration in which 1 molar = 1 mole of solute per 1 liter of solution Calculating molarity: Calculating molarity:

Molarity Example 1: a chemist makes a 400 mL solution by adding 67.4 g of AgNO3 to some water. What is the molarity of this solution? Step 1 – convert from grams to moles

Molarity Example 1: a chemist makes a 400 mL solution by adding 67.4 g of AgNO 3 to some water. What is the molarity of this solution? Example 1: a chemist makes a 400 mL solution by adding 67.4 g of AgNO 3 to some water. What is the molarity of this solution? Step 2 – calculate molarity Step 2 – calculate molarity

Molarity Example 2: how many moles of a solute are present in 34 mL of 3.64 M Ba(OH) 2 ? Example 2: how many moles of a solute are present in 34 mL of 3.64 M Ba(OH) 2 ?

Making Dilutions Would adding water to a concentrated solution dilute it? Would adding water to a concentrated solution dilute it? Yes Yes Would diluting a solution change the number of moles of solute present in the sample? Would diluting a solution change the number of moles of solute present in the sample? No, it would only make the volume bigger. No, it would only make the volume bigger.

Making Dilutions

2.3 moles of sodium chloride in 0.45 liters of solution. 2.3 moles of sodium chloride in 0.45 liters of solution. 1.2 moles of calcium carbonate in 1.22 liters of solution. 1.2 moles of calcium carbonate in 1.22 liters of solution moles of sodium sulfate in 12.0 mL of solution moles of sodium sulfate in 12.0 mL of solution.

120 grams of calcium nitrite in 240 ml of solution. 120 grams of calcium nitrite in 240 ml of solution. 2L of 6M HCI 1.5L of 2M NaOH 2L of 6M HCI 1.5L of 2M NaOH 45 ml of 0.12 M sodium carbonate 45 ml of 0.12 M sodium carbonate

Making Dilutions Example: Suzie needs 3L of a 0.05M HCl. She only has 12M HCl available. How much does she need to dilute to make her solution? Example: Suzie needs 3L of a 0.05M HCl. She only has 12M HCl available. How much does she need to dilute to make her solution?

Percent Solutions Two ways of expressing concentrations by percent: Two ways of expressing concentrations by percent: Volume/volume (%(v/v)): Volume/volume (%(v/v)): Mass/volume (%(m/v)): Mass/volume (%(m/v)):

Percent Solutions Example 1: a bottle of juice claims to be 12%(v/v) pure fruit juice. You run expensive tests and determine that, in 500 mL of juice, there is 58 mL of pure juice. Does the company have a law suit coming up? Example 1: a bottle of juice claims to be 12%(v/v) pure fruit juice. You run expensive tests and determine that, in 500 mL of juice, there is 58 mL of pure juice. Does the company have a law suit coming up?

Percent Solutions Example 1: a bottle of juice claims to be 12%(v/v) pure fruit juice. You run expensive tests and determine that, in 500 mL of juice, there is 58 mL of pure juice. Does the company have a law suit coming up? Example 1: a bottle of juice claims to be 12%(v/v) pure fruit juice. You run expensive tests and determine that, in 500 mL of juice, there is 58 mL of pure juice. Does the company have a law suit coming up?

Percent Solutions Example 2: A student needs to make a 25% (m/v) NaCl solutions. To make 367 mL, how much NaCl is needed? Example 2: A student needs to make a 25% (m/v) NaCl solutions. To make 367 mL, how much NaCl is needed?