Answer:
- 386.6 kJ/mol.
Explanation:
- To solve this problem, we can use Hess's Law:
<em>ΔHrxn = ΣΔHf(products) - ΣΔHf(reactants) </em>
<em></em>
- For this reaction: <em>Ca(s)+ 2H₂O(l) → Ca(OH)₂(s) + H₂(g)</em>,
<em>∴ ΔHrxn = ΣΔHf(products) - ΣΔHf(reactants) = [ΔHf(Ca(OH)₂(s)) + ΔHf(H₂)(g)] - [ΔHf(Ca)(s) + 2*ΔHf(H₂O)(l)].</em>
ΔHf(Ca(OH)₂(s)) = - 985.2 kJ/mol, ΔHf(H₂)(g) = 0.0 kJ/mol, ΔHf(Ca)(s) = 0.0 kJ/mol, ΔHf(H₂O)(l) = - 285.8 kJ/mol.
<em>∴ ΔHrxn = ΣΔHf(products) - ΣΔHf(reactants) = [ΔHf(Ca(OH)₂(s)) + ΔHf(H₂)(g)] - [ΔHf(Ca)(s) + 2*ΔHf(H₂O)(l)] </em>= [(- 985.2 kJ/mol) + (0.0 kJ/mol)] - [(0.0 kJ/mol) + 2*(- 285.8 kJ/mol)] = <em>- 386.6 kJ/mol.</em>
The correct answer to this item is letter
C. convection in earth's mantle
Convection currents move tectonic plates when the rising mantle creates heat inside. The radioactive decay of several substances is responsible for the creation of the convection currents.
The measure of the quantity of heat exchanged.
Uses many different units of measurements.