Ia 14

Chemistry Investigation 14:
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To determine the enthalpy change of reaction for:
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Na2CO3(aq) + H2O(l) + CO2(g) → 2NaHCO3(aq)

Given:
S1— Anhydrous sodium carbonate (Na2CO3)
S2— Anhydrous sodium hydrogen carbonate (NaHCO3)
A1—Aqueous sulfuric acid (H2SO4), 0.500mol dm-3

Apparatus | Uncertainty | Measuring cylinder | ± 0.5 ml | Electronic Balance | ± 0.001 g | Data logger | ±0.2 ℃ |

Data Collection:

S1
Weight of S1 (Weight of weighing bottle & S1 ±0.001)/g | 4.583 | (Weight of weighing bottle ±0.001) /g | 3.459 | (Weight of S1 ±0.002)/g | 1.124 | (Weight of residue & weighing bottle ±0.001)/g | 3.461 | (Actual weight of S1 transferred ±0.002)/g | 1.122 |

Temperature change (Temperature before S1 added±0.2)/ ℃ | 24.0 | (Temperature after S1 added±0.2)/ ℃ | 27.7 | (Temperature increase±0.4)/ ℃ | 3.7 |

Observation:
The white powder completely dissolves in the solution and the solution remains colorless.

S2
Weight of S2 (Weight of weighing & S2 ±0.001)/g | 5.268 | (Weight of weighing ±0.001) /g | 3.460 | (Weight of S2±0.002)/g | 1.808 | (Weight of residue & weighing bottle±0.001)/g | 3.462 | (Actual weight of S2 transferred±0.002)/g | 1.806 |

Temperature change (Temperature before S2 added±0.2)/ ℃ | 23.0 | (Temperature after S2 added±0.2)/ ℃ | 19.3 | (Temperature decrease±0.4)/ ℃ | 3.3 |

Observation:
The white powder completely dissolves in the solution and the solution remains colorles.

Data Processing:

S1
Na2CO3(s) + H2SO4(aq) → Na2SO4(aq) + H2O(l) + CO2(g)

Calculationn(H2SO4)=25.01000×0.500=0.0125moln(Na2CO3)=1.12222.99×2+12.01+16×3=0.010586molSince n(Na2CO3) <n(H2SO4),Na2CO3 is the limiting agent.∆H=mc∆Tn =-(25+1.122)×4.18×3.70.010586=-38.2 KJ mol-1∴∆H=-(38±5) KJ mol1 | Uncertainty%