Determination of Enthalpy Change of Neutralization
CHEMISTRY
DETERMINATION OF ENTHALPY CHANGE OF NEUTRALIZATION
IA Criteria Assessed: DCP CE MS
Introduction
When an alkali neutralizes an acid, a salt and water are formed. Aqueous hydrogen ions (H+(aq)) from the acid react with the hydroxide ions (OH- (aq)) from alkali, forming water. The identity of salt will depend on the nature of the acid and alkali used.
H+(aq) + OH- (aq) → H2O(L)
The combination of H+ and OH- ions in this way releases energy. In this practical, the enthalpy changes accompanying different neutralization reaction will be measured. Because the number of moles of water formed varies according to the acid and alkali used, it is the convention to measure enthalpy change of neutralization in kJ mol-1 per mol of water formed.
Data Collection
Uncertainties
Measuring cylinder: ±0.5ml
Thermometer: ±0.25℃
a) Qualitative data Material | Color | Sodium hydroxide solution 25ml 1M | Colorless aqueous | Hydrochloric acid 25ml 2M | Colorless aqueous | Ethanoic acid 25ml 2M | Colorless aqueous | The temperature of reactant increases |
b) Quantitative data 1. HCI + NaOH → NaCl + H2O Time/±0.01s | Temp/±0.25℃ | 0.00±0.01 | 29.00±0.25℃ | 60.00±0.01 | 29.00±0.25℃ | 120.00±0.01 | 29.00±0.25℃ | 180.00±0.01 | 29.00±0.25℃ | 240.00±0.01 | 35.00±0.25℃ | 300.00±0.01 | 35.00±0.25℃ | 360.00±0.01 | 34.50±0.25℃ | 420.00±0.01 | 34.00±0.25℃ | 480.00±0.01 | 33.00±0.25℃ | 540.00±0.01 | 32.50±0.25℃ | 600.00±0.01 | 32.50±0.25℃ | 660.00±0.01 | 32.00±0.25℃ | 720.00±0.01 | 31.00±0.25℃ | 780.00±0.01 | 31.00±0.25℃ |
2. CH3COOH + NaOH → CH3COONa + H2O Time/±0.01s | Temp/±0.25℃ | 0.00±0.01 | 29.50±0.25℃ | 60.00±0.01 | 29.50±0.25℃ | 120.00±0.01 | 29.50±0.25℃ | 180.00±0.01 | 29.50±0.25℃ | 240.00±0.01 | 34.00±0.25℃ | 300.00±0.01 | 35.00±0.25℃ | 360.00±0.01 | 34.50±0.25℃ | 420.00±0.01 | 34.50±0.25℃ | 480.00±0.01 | 34.50±0.25℃ | 540.00±0.01 | 34.00±0.25℃ | 600.00±0.01 |
DETERMINATION OF ENTHALPY CHANGE OF NEUTRALIZATION
IA Criteria Assessed: DCP CE MS
Introduction
When an alkali neutralizes an acid, a salt and water are formed. Aqueous hydrogen ions (H+(aq)) from the acid react with the hydroxide ions (OH- (aq)) from alkali, forming water. The identity of salt will depend on the nature of the acid and alkali used.
H+(aq) + OH- (aq) → H2O(L)
The combination of H+ and OH- ions in this way releases energy. In this practical, the enthalpy changes accompanying different neutralization reaction will be measured. Because the number of moles of water formed varies according to the acid and alkali used, it is the convention to measure enthalpy change of neutralization in kJ mol-1 per mol of water formed.
Data Collection
Uncertainties
Measuring cylinder: ±0.5ml
Thermometer: ±0.25℃
a) Qualitative data Material | Color | Sodium hydroxide solution 25ml 1M | Colorless aqueous | Hydrochloric acid 25ml 2M | Colorless aqueous | Ethanoic acid 25ml 2M | Colorless aqueous | The temperature of reactant increases |
b) Quantitative data 1. HCI + NaOH → NaCl + H2O Time/±0.01s | Temp/±0.25℃ | 0.00±0.01 | 29.00±0.25℃ | 60.00±0.01 | 29.00±0.25℃ | 120.00±0.01 | 29.00±0.25℃ | 180.00±0.01 | 29.00±0.25℃ | 240.00±0.01 | 35.00±0.25℃ | 300.00±0.01 | 35.00±0.25℃ | 360.00±0.01 | 34.50±0.25℃ | 420.00±0.01 | 34.00±0.25℃ | 480.00±0.01 | 33.00±0.25℃ | 540.00±0.01 | 32.50±0.25℃ | 600.00±0.01 | 32.50±0.25℃ | 660.00±0.01 | 32.00±0.25℃ | 720.00±0.01 | 31.00±0.25℃ | 780.00±0.01 | 31.00±0.25℃ |
2. CH3COOH + NaOH → CH3COONa + H2O Time/±0.01s | Temp/±0.25℃ | 0.00±0.01 | 29.50±0.25℃ | 60.00±0.01 | 29.50±0.25℃ | 120.00±0.01 | 29.50±0.25℃ | 180.00±0.01 | 29.50±0.25℃ | 240.00±0.01 | 34.00±0.25℃ | 300.00±0.01 | 35.00±0.25℃ | 360.00±0.01 | 34.50±0.25℃ | 420.00±0.01 | 34.50±0.25℃ | 480.00±0.01 | 34.50±0.25℃ | 540.00±0.01 | 34.00±0.25℃ | 600.00±0.01 |