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青州's Question
Chemistry
Posted 7 months ago

A can with water is heated up due to a chemical reaction: CaO+H2O>Ca(OH)2\mathrm{CaO}+\mathrm{H} 2 \mathrm{O}->\mathrm{Ca}(\mathrm{OH}) 2 Calculate the mass of water that is needed to heat up 400 mLH2O400 \mathrm{~mL} \mathrm{H} 2 \mathrm{O} about 75 K75 \mathrm{~K}.

Enthalpy of formation CaO: ΔH(CaO)=635,09 kJ/mol\Delta \mathrm{H}(\mathrm{CaO})=-635,09 \mathrm{~kJ} / \mathrm{mol}. Enthalpy of formation Ca(\mathrm{Ca}( OH)2:ΔH(Ca(OH)2)=986,1 kJ/mol\mathrm{OH}) 2: \Delta \mathrm{H}(\mathrm{Ca}(\mathrm{OH}) 2)=-986,1 \mathrm{~kJ} / \mathrm{mol}. Enthalpy of formation H2O:ΔH(H2O\mathrm{H} 2 \mathrm{O}: \Delta \mathrm{H}(\mathrm{H} 2 \mathrm{O} )=285,83 kJ/mol=-285,83 \mathrm{~kJ} / \mathrm{mol}

Heat capacities: c(H2O)=4,18 J/(g K).c(\mathrm{c}(\mathrm{H} 2 \mathrm{O})=4,18 \mathrm{~J} /\left(\mathrm{g}^{*} \mathrm{~K}\right) . \mathrm{c}( can + reaction substances ):449 J/K): 449 \mathrm{~J} / \mathrm{K}
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Answer from Sia
Posted 7 months ago
Solution
1
Calculate the total heat required to raise the temperature of water: To find the total heat required to raise the temperature of 400 mL of water by 75 K, we use the formula q=mcΔTq = mc\Delta T, where mm is the mass of the water, cc is the specific heat capacity of water, and ΔT\Delta T is the change in temperature
2
Convert volume of water to mass: Assuming the density of water is approximately 1 g/mL1 \text{ g/mL}, the mass of 400 mL of water is 400 g
3
Calculate the heat required for the water: Using the specific heat capacity of water (4.18 J/gK4.18 \text{ J/g}\cdot\text{K}), the heat required is q=(400 g)×(4.18 J/gK)×(75 K)q = (400 \text{ g}) \times (4.18 \text{ J/g}\cdot\text{K}) \times (75 \text{ K})
4
Calculate the enthalpy change for the reaction: The enthalpy change for the reaction can be found using the enthalpies of formation: ΔHreaction=ΔHproductsΔHreactants\Delta H_{\text{reaction}} = \Delta H_{\text{products}} - \Delta H_{\text{reactants}}
5
Determine the mass of water needed for the reaction: The mass of water needed can be found by equating the heat absorbed by the water to the enthalpy change of the reaction
Answer
[Insert final answer here]
Key Concept
Thermochemistry and heat transfer
Explanation
The problem involves calculating the heat required to raise the temperature of water and then relating it to the enthalpy change of a chemical reaction to find the mass of water needed.

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