AP Chemistry Lab No. 3: What Makes Water Hard?

tudents will investigate the suitability of gravimetric analysis for determining the amount of water hardness in the form of calcium carbonate found in various water samples. The activity contains enough materials for 15 groups of students as well as a Teacher’s Guide and Student Study Guide Copymasters. Meets Big Idea 1, Investigation 3, Primary Learning Objective 1.19

Kit Includes:

• 40g Calcium Chloride
• 50g Sodium Carbonate
• 500mL Sodium Carbonate 0.5M
• 2 Filter Paper, pk/100
• 200mL Water Sample #1 (0.75M Calcium Chloride)
• 200mL Water Sample #2 (0.2M Calcium Chloride)
• 200mL Water Sample #3 (0.5M Calcium Chloride)
• 200mL Water Sample #4 (0.1M Calcium Chloride)
• 200mL Water Sample #5 (0.05M Calcium Chloride)
• 200mL Water Sample #6 (0.9M Calcium Chloride)

Materials needed but not supplied:

• 250mL Beakers
• 100mL Beakers
• 100mL Graduated Cylinders
• Watch Glasses
• Distilled or Deionized Water
• Wash Bottles
• Analytical Balance(s) (0.001g resolution or better)
• Drying Oven
• Vacuum filtration setups (aspirators or small vacuum pumps, 250mL Buchner funnels, 250mL Erlenmeyer flasks w/sidearm, ring stands w/ laboratory clamps, rubber tubing, glass tubing, #6 two-hole rubber stoppers, #6 Buchner funnel rubber stoppers)