1. Chemistry 11 Introduction to Molarity Lesson 1

2. Chemists need to make solutions that have precise concentrations

3. Pesticides must be in proper concentrations. Food additives must be in correct concentrations. A driver is legally impaired at 0.08 mg/mL blood alcohol content. A new driver is legally impaired at 0.00 mg/mL blood alcohol content. Chemists control the concentration of chemicals using the concepts we will develop in this unit.

4. The concentration of a solution tells you how much solute that is dissolved in a given amount of solvent (water). The molarity is the concentration of a solution. Molarity= Moles Litre

5. 1.2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the molarity. Molarity=2.255 moles 4.0 L =0.56 moles/litre =0.56 M (Molar) M means moles per 1 litre

6. =0.356 M 0.250 L 56.11 g x 1 mole5.00 g Molarity = 2.5.00 g KOH is dissolved in 250. mL of water, calculate the molarity.

7. 3.How many grams are there in 205. mL of a 0.172 M solution of NaCl? 1 L x 0.172 moles0.205 Lx 58.5 g 1 mole = 2.06 g

8. =2.62 L 0.500 mole x 1L1 mole 95.3 g 125 g x 4.How many litres of 0.500 M MgCl 2 solution contain 125 g MgCl 2 ?

9. 5.How many grams of NaCl must be used to prepare a 100.0 mL of 0.250 M solution. = 1.46 g 1 mole x 58.5 gx 0.250 moles 1 L 0.1000 L

10. 6.How many millilitres of a 0.200 M solution of CoCl 2 will contain 25.0 g ? = 962 mL 1 L x 1000 mL 0.200 mol x 1 L 129.9 g x 1 mole25.0 g

11. 7.Describe how you would prepare 100.0 mL of a 0.200 M solution of CoCl 2. Transfer and rinse to a 100 mL volumetric flask- fill to the line Dissolve in water Weigh 2.60 g of CoCl 2 = 2.60 g 1 mole x 129.9 g 1 L x 0.200 moles0.1000 L