PURPOSE:

In this lab we will observe exothermic and endothermic reactions and determine if they are spontaneous at room temperature

Teacher Demonstration In the hood with the fan on is placed 3 grams of potassium permanganate on each (2) glass squares. Make a cavity in the center of the solid. One ml of cold glycerol is added to one pile of potassium permanganate. One ml of warm glycerol is added to the other pile of potassium permanganate. Observe the reactions and note the products.

The second demonstration involves damp sugar again under the hood with the fan on. Make a cavity in the center of the sugar. Pour in concentrated sulfuric acid. Observe the reactions and note the products.

Record your observations of these reactions regarding heat and products formed.

Student Procedure

Read the MSDS sheets for safety precautions and disposal of chemicals.
1. Take the temperature of 100 ml of distilled water in a clean styrofoam cup. Add 5.3 grams of ammonium chloride and stir with the thermometer and record the highest or lowest temperature reached.
2. Do step one again, but use 4 grams of sodium hydroxide in 100 ml of water.
3. Take the temperature of 50 ml of 1 M HCl to the nearest 0.2^oC. In the styrofoam cup take the temperatue of 50 ml of 1 M NaOH that remained from step 2. Mix these chemicals together in a styrofoam cup and record the highest or lowest temperature reached.
4. Record your observations of these reactions regarding heat and products formed.

Conclusion:

1. Determine the number of calories absorbed or given off by each of your reactions and tell if they are endothermic or exothermic.

2. For reaction #3 tell how many moles of water were formed after showing the balanced equation.

        calories = ml X temperature change 

3. Discuss your observations of the teacher demonstration.