Calorimetry Worksheet 2 Answers Chemsheets Updated – Hot

| Mistake | Correction | |---------|-------------| | Forgetting sign of ( \Delta H ) | Exothermic = negative, endothermic = positive | | Using ( m ) of fuel instead of water | ( m ) = mass of surroundings (water/solution) | | Ignoring heat capacity of calorimeter | If given calorimeter constant ( C ), use ( q = C\Delta T + m_\textwaterc\Delta T ) | | Wrong ( \Delta T ) (e.g., using final only) | ( \Delta T = T_\textfinal - T_\textinitial ) | | Units not converted to kJ | ( \Delta H ) usually in kJ mol⁻¹ → divide J by 1000 |

Mass of water = 200 g Initial temp = 19.2 °C Final temp = 37.8 °C Mass of ethanol burned = 0.46 g ( M_r(\textC_2\textH_5\textOH) = 46.0 ) calorimetry worksheet 2 answers chemsheets

ΔH_combustion = -2230 kJ/mol (Literature value for ethanol is ~-1367 kJ/mol? Check – this high value indicates significant heat loss. In worksheet answers, they often accept calculated value; refine by using q = mcdT correctly. Actually recalc: 12.122 kJ / 0.005435 mol = 2230 kJ/mol. If heat loss ignored, it's correct per data.) Actually recalc: 12

) in a polystyrene cup. The initial temperature of both solutions was . After mixing, the maximum temperature reached was . Calculate the enthalpy change of neutralization. Step 1: Calculate the mass of the solution ( Combine the volumes of both solutions: After mixing, the maximum temperature reached was

) should be the mass of the water (or the total solution), not just the solid added. 1.0 cm3c m cubed of an aqueous solution is generally treated as 1.0 2. Neutralization Reactions The Scenario: Mixing HClcap H cap C l NaOHcap N a cap O cap H

q=m×c×ΔTbold q equals bold m cross bold c cross bold cap delta bold cap T = Heat energy change (measured in Joules, J).

A spirit burner containing ethanol was weighed before and after combustion. The mass of the burner decreased by . The energy released heated of water in a copper calorimeter from 20.0∘C20.0 raised to the composed with power C 55.5∘C55.5 raised to the composed with power C . Calculate the enthalpy of combustion of ethanol ( Step 1: Calculate the heat energy absorbed by the water (