Calorimeter lab. What is the change in enthalpy for magnesium after the reaction with vinegar?

Hypothesis:

         If the magnesium reacts with vinegar then the change in enthalpy will be a very high value.

Procedure:

All materials were gathered and cleaned.

The vinegar of 20 ml was measured using two 10 ml graduated cylinder to get a precise amount of vinegar.

The vinegar was put into a Styrofoam cup.

Another Styrofoam cup was put over the first cup for insulation.

The piece of the magnesium was measured and recorded.

The apparatus was moved to the front of the class where the teacher set up the thermometer attached to the laptop showing the temperature.

A Styrofoam cup with two holes for the thermometer and another for the stirring rod was set up and was placed on top of the apparatus as tightly as possible so not a lot of the gas can escape.

The initial temperature was measured using the thermometer.

The top was removed, the magnesium was added and quickly the top was placed back on to the top.

The stirring rod was used to mix the solution inside the calorimeter.

The thermometer connected to the computer showed the temperature increase and decrease as a graph. If the graph plateaued or started to constantly decrease the apparatus was removed from the thermometer and the finial temperature was recorded.

Observations:

        Initial temperature = 24.7 °C

        Final temperature = 52.7 °C

        Amount of vinegar = 20.0 mL

        Mass of Mg = 0.2 g

Analyzing and Interpreting:

        Mg + 2CH3COOH -> Mg (CH3COO)2 + H2

        ΔH = ?

        ΔT = TFinal – TInitial

             

             

        C =4.184 J/g °C

        D= 1.00 g/mL

        mVinegar= 20.0 mL x 1.00 g/mL

                = 20.0 g

        mTotal= mVinegar + mmg

        

        Q = mTotal x c x ΔT

        Q = 20.2 g x 4.184 J/g °C x 28.0 °C

            = 2366.4704 J

        nmg = m ÷ M

       = 0.2 g ÷ (24.31 g/mol)

 mol

        ΔH = -Q ÷ nmg

               = -2366.4704 J ÷ 0.0082 mol

              = -288.59 kJ/mol

The change of enthalpy is -288.59 kJ/mol for the magnesium.

Conclusion

        The hypothesis was right because the change of enthalpy of the magnesium is -288.59 kJ/mol. A lot of heat is released from this reaction. 0.2 g of magnesium was used with 20.0 mL of vinegar. The initial temperature of the calorimeter was 24.7 °C and the finial being 52.7 °C. The magnesium reacts with vinegar (CH3COOH) because of the oxygen present. The reactivity of the magnesium increase as the oxygen level increases. This single displacement reaction of the magnesium and the vinegar reacts and forms hydrogen gas.

Reference:

        Biology 12. Toronto: McGraw-Hill Ryerson, 2011. Print.