Unit 1: Calorimetry and Osmosis

How to prepare simple calorimetry experiment

1. Measure out a fixed volume (20 cm³) and pour it into a test tube

2. Clamp test tube to clamp and stand

3. Use thermometer to measure the water’s initial temperature

4. weight food sample

5. skewer food sample using needle

6. hold the food over Bunsen burner

7. immediately after it catches fire, place it under test tube

8. if food goes out but doesn’t fully burn, relight it immediately

9. find out final temperature of water

10. measure final mass of the burnt food

Energy content equation

4.2 x mass burnt x temperature change

Why is simple calorimetry experiment not accurate

• Heat energy is lost to the surroundings

• water lost via evaporation

• incomplete combustion

Why is bomb calorimetry more accurate

1. food is ignited inside a sealed container - no heat is lost

2. stirrer is used - even heat distribution

3. no water lost through evaporation

4. complete combustion

Diffusion

the net movement of particles form an area of high concentration to an area of low concentration

osmosis

the net movement of water particles through a partially permeable membrane from high water potential to low water potential.

active transport

The movement of substance against their concentration gradient from an area of low concentration to high concentration using protein carriers on cell membranes using energy.

potato practical

1. label 6 boiling tubes A-F

2. Dry 6×3cm long potato with paper towel

3. weigh and record the mass of each potato cylinder

4. place one in each boiling tube

5. cover with solutions of the same volume with different concentrations

6. leave for 20 minutes

7. remove, dry and weigh each potato

8. record mass of each potato