Easy Stoichiometry Problems - Chemistry?

2017-07-25 10:28 pm

Chlorine can be produced in the laboratory by the reaction of hydrochloric acid with excess manganese (IV) oxide.
4HCl + MnO_2 -> Cl_2 + 2H_2O + MnCl_2
a) How many moles of HCl are needed to form 12.5 mole Cl_2
b) What is the mass of the water produced?
c) How many g of manganese oxide reacted with hydrochloric acid?

更新1:

So my answers are a) 50 moles b) 36g c) 86.94g . I'm just wondering if my answers are correct... :)

回答 (1)

micatkie

2017-07-25 10:45 pm

✔ 最佳答案

a)
4HCl + MnO₂ → Cl₂ + 2H₂O + MnCl₂
Mole ratio HCl : Cl₂ = 4 : 1

No. of moles of Cl₂ produced = 12.5 mol
No. of moles of HCl needed = (12.5 mol) × 4= 50.0 mol

b)
4HCl + MnO₂ → Cl₂ + 2H₂O + MnCl₂
Mole ratio Cl₂ : H₂O = 1 : 2

No. of moles of Cl₂ produced = 12.5 mol
No. of moles of H₂O produced = (12.5 mol) × 2= 25.0 mol

Molar mass of H₂O = (1.0×2 + 16.0) g/mol = 18.0 g/mol
Mass of H₂O produced = (25.0 mol) × (18.0 g/mol) = 450 g

c)
4HCl + MnO₂ → Cl₂ + 2H₂O + MnCl₂
Mole ratio MnO₂ : Cl₂ = 1 : 1

No. of moles of MnO₂ reacted = No. of moles of Cl₂ produced = 12.5 mol

Molar mass of MnO₂ = (54.9 + 16.0×2) g/mol = 86.9 g/mol
Mass of MnO₂ reacted = (12.5 mol) × (86.9 g/mol) = 1090 g

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