Exothermic Reaction Lab

Experiment 13.1
Purpose: To determine the ∆H of a chemical reaction.
Materials: 2 Styrofoam cups, Thermometer, Vinegar, Mass Scale, Measuring tablespoon and ½ teaspoon, Lye, and Safety goggles.
Question: Can you determine the ∆H of a chemical reaction?
Hypothesis: The ∆H of a chemical reaction can be found through experimentation.
Background: The ∆H is the amount of H (Enthalpy: the energy stored in a substance) that has changed from the initial to the final. There are equations that can determine the ∆H.
Procedure: Measure 10 tablespoons of lye, and divide the mass by 30. The quotient will be the mass of 1 teaspoon of lye.
Now divide the mass of 1 teaspoon of lye by 2 to get ½.
Combine the two Styrofoam cups together to make a makeshift calorimeter. Pour 100.0 ml of

Read the temperature every 30 seconds, stop when the temperature stays constant for 2 consecutive readings.
Now use the equation (q = m × c × ∆T) to obtain the amount of heat transferred. Ignore the calorimeter.
The specific heat (c) of vinegar is 4.1 J/g × C.
The mass of the vinegar (m) will be the volume (100.0 ml) times the density (0.99 g/ml), and add the mass of ½ teaspoon of lye.
Subtract the initial temperature from the final temperature to get ∆T.
Now using these numbers, use the equation above to solve for q. This will also be the ∆H of the reaction.
However, now you must take the mass of lye and divide it by the molar mass of NaOH to obtain the number of moles.
Now divide the ∆H by the number of moles to get ∆H J/moles.
Finally, clean everything up.
Discussion: The mass of the lye was taken twice, and the mass of half a teaspoon of lye is 3.3 grams, as 1 teaspoon of lye was 6.6 grams. The initial temperature of the vinegar was 16.0° C.
For the first trial, the final temperature was 31.0°C, meaning the ∆T was 15.0°C. The final temperature for the second trial was 33.5°C, which indicates that the ∆T was 17.5°C.
The mass of the vinegar was 99