Question

Suppose a sodium hydroxide solution was standardized against pure solid primary standard grade KHP. If 0.4798 g of KHP required 45.22 mL of the sodium hydroxide to reach a phenolphthalein endpoint, what is the molarity of the NaOH solution?

Answer 1

Answer:

The NaOH solution has a molarity of 0.052 M

Explanation:

Step 1: Data given

Mass of KHP = 0.4798 grams

Volume of NaOH= 45.22 mL = 0.04522 L

Molar mass of NaOH = 40 g/mol

Molar mass of KHP = 204.22 g/mol

Step 2: Calculate moles of KHP

Moles KHP = mass KHP / Molar mass KHP

Moles KHP = 0.4798 grams / 204.22 g/mol

Moles KHP = 0.00235 moles

Step 3: Calculate moles of NaOH

KHP here acts as a mono-acid so, the number of moles of NaOH = number of moles KHP = 0.00235 moles

Step 4: Calculate molarity of NaOH

Molarity NaOH = moles NaOH / volume NaOH

Molarity NaOH = 0.00235 moles / 0.04522 L

Molarity NaOH = 0.052 M

The NaOH solution has a molarity of 0.052 M