Question

What mass of sodium hydroxide is needed to make 0.500 L of 2.50 M NaOH ?

Answer 1

Answer:

50 g NaOH

General Formulas and Concepts:

Chemistry - Solutions

• Reading a Periodic Table
• Using Dimensional Analysis
• Molarity = moles of solute / liters of solution

Explanation:

Step 1: Define

0.500 L

2.50 M NaOH

x moles of solute

Step 2: Define conversions

Molar Mass of Na - 22.99 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H - 1.01 g/mol

Molar Mass of NaOH - 22.99 + 16.00 + 1.01 = 40 g/mol

Step 3: Find moles of solute

2.50 M NaOH = x moles NaOH / 0.500 L

x = 1.25 moles NaOH

Step 4: Convert

$1.25 \ mol \ NaOH(\frac{40 \ g \ NaOH}{1 \ mol \ NaOH} )$ = 50 g NaOH

Step 5: Check

We are given 3 sig figs. Since our final answer has 2 sigs, there is no need to round.