Step-by-step explanation:
The reaction of neutralization involved:
2 HCl (aq) + Ca(OH)2 (aq) => CaCl2 (aq) + 2 H2O (l) (completed and balanced)
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Data provided:
Case a)
2 moles HCl
2 moles Ca(OH)2
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Case b)
2 moles HCl
0.5 moles Ca(OH)2
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Procedure: Case a)
By stoichiometry,
2 HCl (aq) + Ca(OH)2 (aq) => CaCl2 (aq) + 2 H2O (l)
2 moles HCl ------- 1 mole Ca(OH)2
2 moles HCl ------- X
X = 2 moles HCl x 1 mole Ca(OH)2/2 moles HCl
X = 1 mole Ca(OH)2
For 2 moles of HCl, 1 mole of Ca(OH)2 is needed, but in case a) there are 2 moles of Ca(OH)2, so the limiting reactant is HCl.
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Procedure: Case b)
By stoichiometry,
2 HCl (aq) + Ca(OH)2 (aq) => CaCl2 (aq) + 2 H2O (l)
2 moles HCl ------- 1 mole Ca(OH)2
2 moles HCl ------- X
X = 2 moles HCl x 1 mole Ca(OH)2/2 moles HCl
X = 1 mole Ca(OH)2
For 2 moles of HCl, 1 mole of Ca(OH)2 is needed, but there are 0.5 moles of Ca(OH)2, so the limiting reactant is Ca(OH)2.