Determination of enthalpy change of neutralization and
combustion of a liquid
G11 Nana, Lynn, Anne, Joesy, Eric
January 24, 2024
Purpose:
To determination of enthalpy change of neutralization and
combustion of a liquid.
Safety precautions:
1. lab coat
2. safety goggles
Apparatus:
Tripod, pipette, beaker, alcoholburner, thermometer, polystyrene
cup, lid.
Chemicals:
1. HCl- hydrochloric acid
2. NaOH- sodium hydroxide
3. Water
Steps:
1. Add water to a flask, weight the water.
2. Clamp the flask to a stand at a suitable height, and put a spirit
burner.
3. Weigh the spirit burner.
4. Record the initial temperature of the water by thermometer.
5. Extinguish the flame.
6. Record the final temperature of the water.
7. Re-weigh the spirit burner.
8. Calculate the enthalpy change of combustion.
1. Wear safety glasses and a lab coat.
2. Using a pipette fitted with a safety filler, place 25.0cm³ of 1.00
mol dm acid into an expanded polystyrene cup.
3. Measure the temperature of acid.
4. Using a pipette fitted with a safety filler, place 25.0 cm³ of the
alkali into a beaker.
5. Measure the temperature of the alkali.
6. Add the alkali to the acid, stir with the thermometer and measure
the maximum temperature reached.
Calculation:
volume of water heated
66.8cm^3
mass of ethanol burned
2.1g
temperature change
+303k
4.18 x 2.1 x66.8 = 0.5864KJ
2.1/46 =0.0457mol
0.5864/0.0457= 12.83KJ/mol
volume of 1mol/dm^3HCl
25.0cm^3
volume of 1mol/dm^3NaOH
25.0cm^3
initial temperature of acid
11
initial temperature of alkali
15
maximum temperature reached 14
4.18 x (14-0.5(11+15)) x (25+25) = 0.209KJ
-0.209/0.025= -83.6KJ/mol
Errors:
We made several mistakes in the experiment. First, we did not
handle the alcohol lamp lightly at the beginning. Second, due to the
lack of experimental equipment, the data is not accurate enough.
For example, there is no copper beaker that can better conduct
heat and a container that can reduce heat loss. Failure to measure
the initial temperature value in time during the experiment may
lead to inaccurate experiment. Then when the experiment was over
there was no alcohol lamp covered twice.
In the second experiment, when we used pipeet, we did not read
the line of sight at the concave level, resulting in inaccurate
readings. We don’t have draught shield. And for both experiment is
not under standard condition.
Improvements:
1. Becareful about alcohol burner.
2. Measure the temperature of water before the experiment.
3. Use a well conduct heat container and use a lid for reduce heat
loss.
4. Use thermometer and pippet should be same with eye level.