Answer:
a. The reaction is exothermic.
b. -87,9 kJ
c. 9,60g of Mg(s)
d. 602kJ are absorbed
Explanation:
Based on the reaction:
2Mg(s) + O₂(g) → 2MgO(s) ΔH = -1204kJ
a. The reaction is exothermic. Because ΔH<0. That means the reaction produces heat when occurs
b. 3,55g of Mg(s) are:
3,55g Mg × ( 1mol / 24,305g) = 0,146 moles of Mg(s)
As 2 moles of Mg(s) produce -1204 kJ of heat:
0,146 moles of Mg(s) × ( -1204kJ / 2mol Mg) = <em>-87,9 kJ</em>
c. If -238 kJ of heat were transferred. The moles of Mg(s) that react must be:
-238kJ × ( 2mol Mg / -1204kJ) = 0,395 moles of Mg(s). In grams:
0,395 moles × ( 24,305g / 1mol Mg) = <em>9,60g of Mg(s)</em>
d. The reverse reaction is:
2MgO(s) → 2Mg(s) + O₂(g) ΔH = +1204kJ
40,5g of MgO(s) are:
40,5g MgO × ( 1mol MgO / 40,3044g) = 1,00 moles of MgO(s)
As 2 moles of MgO absorbe 1204kJ of energy:
1,00 moles of MgO(s) × ( +1204 kJ / 2mol MgO) = <em>602kJ are absorbed</em>
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I hope it helps!
