Question

What volume, in mL, of a 2.25 M AgNO₃ solution contains 0.250 lbs of AgNO₃?

Answer 1

Step-by-step explanation:

Molarity = mol/L

M = 2.25 AgNO₃

mass = 0.250 lb AgNO₃

Step 1: We need to change the pounds of AgNO₃ to grams of AgNO₃.

Conversion factors needed

1 kg = 2.2 lb

1 kg = 1000 g

Set up the problem

0.250 lb x (1 kg/2.2 lb) x (1000 g/1 kg) = 250/2.2 = 113.64 g AgNO₃

Note that lb and kg cancel so you are left with g.

Step 2: Convert grams of AgNO₃ to moles AgNO₃.

113.64 g AgNO₃ x (1 mol/169.87 g) = 0.66898 mol AgNO₃

Step 3: Use the definition of molarity to find liters AgNO₃.

M = mol/L

M = 2.25

mol = 0.66898

2.25 = 0.66898/L

L = 0.66898/2.25

L = 0.29732

Step 4: Convert 0.29732 liters to milliliters.

Conversion factor needed

1 L = 1000 mL

Set up the problem

0.29732 L x (1000 mL/1 L) = 297.32 mL

Correct significant figures for the final answer: 297 mL

Note that L cancels and you are left with mL.