Questions and Answers
Considering a higher specific heat for water, will the temperature change in the calorimeter be higher, lower, or unaffected by this technique error?
unaffected
Should the enthalpy of neutralization for all strong acid-strong base reactions be the same within experimental error? Will that also be the case for all weak acid-strong base reactions?
yes, no
Calculate the heat loss to the inner 2.35-g Styrofoam cup with a temperature change of 6.22℃ and a specific heat of 1.34 J/g °C.
19.6 J
If some of the salt remains adhered to the weighing paper and is not transferred to the calorimeter, will the enthalpy of solution be reported too high or too low?
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If the heat change during the dissolution of ammonium nitrate is ignored, will the enthalpy of solution, ΔHs, be reported as too high or too low?
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Study Notes
Calorimetry Concepts
- The specific heat of water is 4.18 J/g °C, which determines how much energy is required for temperature changes.
- Changes in the amount of water do not affect temperature change in the calorimeter, as any increase in water volume correlates with an increase in specific heat, leaving overall temperature change unaffected.
Enthalpy of Neutralization
- Enthalpy of neutralization for strong acid-strong base reactions (e.g., H+ + OH- = H2O) is consistent across experiments, within experimental errors.
- Weak acid-strong base reactions differ from strong acid-strong base ones due to incomplete dissociation of weak acids; thus, their enthalpy is generally lower.
Heat Loss Calculation
- Heat loss to the Styrofoam calorimeter can be calculated using the formula: q = m * specific heat * ΔT.
- For Styrofoam with a mass of 2.35 g and a temperature change of 6.22 °C, the calculated heat loss is approximately 19.6 J.
Impact of Incomplete Transfer
- If some salt remains on the weighing paper and is not added to the calorimeter, the measured enthalpy of solution will be underestimated or reported too low, as it reflects only a portion of the total mass.
Endothermic Processes in Calorimetry
- The dissolution of ammonium nitrate (NH4NO3) is an endothermic reaction, meaning it absorbs heat.
- If heat loss by the calorimeter is ignored, the calculated enthalpy of solution (ΔHs) will be reported too high due to unaccounted heat energy needed to accurately describe the system's energy changes.
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Test your understanding of calorimetry concepts from Experiment 25 with flashcards. Focus on the specific heat of water and its impact on temperature changes. Enhance your knowledge and clarify common technique errors discussed in the lab.
