Solution:
The balanced chemical equation:
2Nal(s) + Cl2(g) = I2(s) + 2NaCl(s)
According to the chemical equation: n(NaI)/2 = n(Cl2) = n(NaCl)/2
1) Calculate moles:
Moles of NaI = Mass of NaI / Molar mass of NaI
The molar mass of NaI is 149.89 g/mol.
Moles of NaI = (4.0 g) / (149.89 g/mol) = 0.0267 mol
Moles of Cl2 = Mass of Cl2 / Molar mass of Cl2
The molar mass of Cl2 is 70.906 g/mol.
Moles of Cl2 = (4.0 g) / (70.906 g/mol) = 0.0564 mol
2) Divide by coefficients of balanced equation:
Sodium iodide (NaI) ⇒ (0.0267 mol) / (2 mol) = 0.01335 mol
Chlorine gas (Cl2) ⇒ (0.0564 mol) / (1 mol) = 0.0564 mol
Sodium iodide (NaI) is the lower value. It is the limiting reagent.
3) Use NaI : NaCl molar ratio:
1 is to 1 as 0.0267 mol is to X
X = 0.0267 mol of NaCl produced
4) Determine grams of NaCl:
Mass of NaCl = Moles of NaCl × Molar mass of NaCl
The molar mass of NaCl is 58.44 g/mol.
Mass of NaCl = (0.0267 mol) × (58.44 g/mol) = 1.56035 g = 1.56 g
5) Actual yield of NaCl = Mass of NaCl × The percentage yield of the reaction
Actual yield of NaCl = (1.56 g) × (0.67) = 1.0452 g = 1.05 g
Answer: 1.05 g is the actual yield of sodium chloride (NaCl).
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