Question

Please help and explain how to get the answer!

Answer 1

Answer 1: The correct answer is option (B)

Answer 2: The correct answer is option (B)

Explanation 1:

$2Na+Cl_2\rightarrow 2NaCl$

moles of NaCl = $\frac{\text{given mass of NaCl}}{\text{molar mass of NaCl}}=\frac{200 g}{58.5 g/mol}=3.4188 mol$

According to reaction, 2 moles NaCl are obtained from 2 moles of Na, then 3.4188 moles of NaCl are obtained from: $\frac{1}{1}\times 3.4188$ moles of Na.

Mass of Na = moles of sodium × Molar mass of sodium

$=23 g/mol\times 3.4188 mol=78.632 g$

From the given option nearest answer to calculated answer is option (B) that is 78.65 g.

Explanation 2:

$2K+2H_2O\rightarrow 2KOH+H_2$

moles of potassium(K)= $\frac{\text{given mass of K}}{\text{molar mass of K}}=\frac{23.5 g}{39 g/mol}=0.6025 mol$

According to reaction, 2 moles of K gives 2 moles of KOH , then 0.6025 moles of K will give : $\frac{1}{1}\times 0.6025 moles$ of KOH

Mass of KOH = moles of KOH × Molar mass of KOH

$0.6025 mol\times 56 g/mol=33.74 g\approx 33.7 g$

From the given option nearest answer to calculated answer is option (A) that 33.7 g.