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Enthalpy of Weak Base and Acid

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Introduction

Experiment 2: Enthalpy of Neutralization of Weak Acid with Weak Base ________________ Weak Base: Ammonium Hydroxide (NH4OH) Weak Acid: Acetic Acid (CH3CO2H) Reaction: NH4OH (aq) + CH3CO2H (aq) --> CH3COONH4 (aq) + H2O (l) Time (s) (±0.05s) Temperature (°C) (±0.05°C) Trial 1 Trial 2 Trial 3 Average Before adding base Initial Temperature 23 23 23 23 60 23 23 23 23 120 23 23 22.5 22.8 180 23 22.5 22.5 22.7 240 22.5 22.5 22.5 22.5 300 22.5 22.5 22 22.3 After adding base Peak Temperature 26.5 27.5 ...read more.

Middle

Least count in Measuring cylinder = 1ml Uncertainty in measuring cylinder = ± 0.5ml Molarity of Acid = 1M Molarity of Base = 1M Processed Data To find enthalpy we can use this equation: Where E = Energy transfer between system and surroundings m = Mass of Substance c = Specific Heat capacity of substance âT = Change in Temperature Volume of solutions cup (Salt + Water) after reaction = 10ml (± 0.5ml) ...read more.

Conclusion

OR 4.9K (± 1K) Percentage error in mass of water: Percentage error in temperature: Percentage error in number of moles = Energy released in reaction: Moles of Hydrogen ions neutralized by Hydroxide ions = = = 0.01 moles (±0.0005 moles) Energy released per mole of hydrogen ions neutralized = = = 40960 J mol-1 or 40.96 kJ mol-1 ï41.0 kJ mol-1 Total uncertainty for enthalpy value = 20.4% + 5% + 5% = 30.4% Absolute uncertainty= ï The standard enthalpy change of neutralization of a weak acid (CH3CO2H) by a weak base (NH4OH) = -41.0 kJ mol-1 ± 12.5 kJ/mol-1 The percentage error compared to literature value: ...read more.

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