Question

What is the mass of 2.1 moles of Sodium Chloride?

Answer 1

120 g NaCl

General Formulas and Concepts:

• Reading a Periodic Table
• Dimensional Analysis (DA)
• Writing compounds

Step-by-step explanation:

Step 1: Define

2.1 moles NaCl (sodium chloride)

Step 2: Define conversions

Molar Mass of Na - 22.99 g/mol

Molar Mass of Cl - 35.45 g/mol

Molar Mass of NaCl - 22.99 + 35.45 = 58.44 g/mol

Step 3: Convert (DA)

`2.1 \ mol \ NaCl((55.84 \ g \ NaCl)/(1 \ mol \ NaCl) )` = 122.724 g NaCl

• mol NaCl and mol NaCl cancel out
• left with g NaCl as final units

Step 4: Check

We have 2 sig figs. Follow sig fig rules.

122.724 g NaCl ≈ 120 g NaCl