Enthalpy Lab
LAB OF ENTHALPY CHANGE IN COMBUSTION
Objective:
Determine the Enthalpy change of combustion ΔHc of three different alcohols. Methanol, Ethanol and Isopropilic acid.
Procedure:
1. Fill the spirit micro burner with Ethanol and weight it 2. Pour 100 cm3 of water into the aluminum cup 3. Arrange the cup a short distance over the micro burner 4. Measure the temperature of water 5. When the temperature of the water has risen by 10°C, record the temperature. 6. Reweight the microburner. Record 7. Repeat steps 1 to 6 but now with Methanol 8. Repeat step 1 to 6 with Isopropilic acid.
Data and Processing Alcohols | Initial mass of microburner fill with alcohol (g)± 0.01 | Final mass of microburner fill with alcohol (g)± 0.01 | Initial temperature of water(°C)± 0.1 | Final temperature of water(°C)± 0.1 | Volume of water in metallic calorimeter (cm3) ±0.5 | Ethanol | 5.38 | 5.08 | 23.0 | 33.0 | 100.0 | Methanol | 5.33 | 4.94 | 24.0 | 34.0 | 100.0 | Isopropolic acid | 5.45 | 5.20 | 24.0 | 34.0 | 100.0 |
Find the mass of water
ρ=mv
ρ (density) H2O = 1.0 g /cm3
Calculate % Uncertainty in mass of water
As the mass of water is the same in the 3 alcohols the %uncertainty is the same for all the alcohols
Absolute uncertainty of the measuring cylindermass of water × 100 Calculating Δ mass change (alcohol’s burned mass)
(initial mass ± 0.01 g)-(final mass ± 0.01 g)
Calculating percentage uncertainty in alcohol burned mass
Absolute uncertainty of alcohol's burned massalcohol's burned mass × 100
Calculate the percentage uncertainty of alcohol burned moles
percentage uncertainty of alcohol burned mass+percentage uncertainty of alcohol`s molar mass
Calculating ΔH (enthalpy change)
ΔH=-mass of water x specific heat of water x Δ T of water mol of alcohol
* The specific heat for water is 4.18
=100x4.184x 10=4,184 J or 4,184 KJ exothermic
Methanol=
* H2O = 100 ml *
Objective:
Determine the Enthalpy change of combustion ΔHc of three different alcohols. Methanol, Ethanol and Isopropilic acid.
Procedure:
1. Fill the spirit micro burner with Ethanol and weight it 2. Pour 100 cm3 of water into the aluminum cup 3. Arrange the cup a short distance over the micro burner 4. Measure the temperature of water 5. When the temperature of the water has risen by 10°C, record the temperature. 6. Reweight the microburner. Record 7. Repeat steps 1 to 6 but now with Methanol 8. Repeat step 1 to 6 with Isopropilic acid.
Data and Processing Alcohols | Initial mass of microburner fill with alcohol (g)± 0.01 | Final mass of microburner fill with alcohol (g)± 0.01 | Initial temperature of water(°C)± 0.1 | Final temperature of water(°C)± 0.1 | Volume of water in metallic calorimeter (cm3) ±0.5 | Ethanol | 5.38 | 5.08 | 23.0 | 33.0 | 100.0 | Methanol | 5.33 | 4.94 | 24.0 | 34.0 | 100.0 | Isopropolic acid | 5.45 | 5.20 | 24.0 | 34.0 | 100.0 |
Find the mass of water
ρ=mv
ρ (density) H2O = 1.0 g /cm3
Calculate % Uncertainty in mass of water
As the mass of water is the same in the 3 alcohols the %uncertainty is the same for all the alcohols
Absolute uncertainty of the measuring cylindermass of water × 100 Calculating Δ mass change (alcohol’s burned mass)
(initial mass ± 0.01 g)-(final mass ± 0.01 g)
Calculating percentage uncertainty in alcohol burned mass
Absolute uncertainty of alcohol's burned massalcohol's burned mass × 100
Calculate the percentage uncertainty of alcohol burned moles
percentage uncertainty of alcohol burned mass+percentage uncertainty of alcohol`s molar mass
Calculating ΔH (enthalpy change)
ΔH=-mass of water x specific heat of water x Δ T of water mol of alcohol
* The specific heat for water is 4.18
=100x4.184x 10=4,184 J or 4,184 KJ exothermic
Methanol=
* H2O = 100 ml *