Question

if you have 10 grams of sodium chloride (nacl), how many moles do you have?
a. 0.17 moles
b. 0.5 moles
c. 2 moles
d. 1 mole

Explanation:

Step1: Calculate molar mass of NaCl

Molar mass of Na ($M_{Na}$) is $22.99\ g/mol$, molar mass of Cl ($M_{Cl}$) is $35.45\ g/mol$. Molar mass of NaCl ($M_{NaCl}$) = $M_{Na}+M_{Cl}=22.99 + 35.45=58.44\ g/mol$.

Step2: Use formula $n=\frac{m}{M}$

Given mass $m = 10\ g$, molar mass $M = 58.44\ g/mol$. Then $n=\frac{10}{58.44}\approx0.17\ mol$.

Answer:

A. 0.17 moles