Question

The titration of .1500 g of unknown acid required 43.65 mL of .103 M NaOH to reach endpoint. What is the molecular weight of unknown solid

Answer 1

The molecular weight of unknown acid is 33.33 g

Step-by-step explanation:

• The reaction between an acid and a base such as NaOH is called a neutralization reaction.
• Neutralization titration may be used to standardize a solution or determine the concentration of solution whose molarity is unknown.
• The balanced equation for reaction between an acid and Sodium hydroxide is

HX(aq)+ NaOH(aq) → NaX(aq)+ H₂O(l)

We need to determine the molecular weight of the acid;

Step 1: Moles of Sodium hydroxide

Number of moles is given by multiplying molarity and volume of the solution.

Number of moles = Molarity × Volume

= 0.103 M × 0.04365 L

= 0.0045 Moles NaOH

Step 2: Moles of the acid

The mole ratio of the acid to NaOH is 1:1

Therefore; the moles of the acid will be 0.0045 moles

Step 3: Molecular weight of the acid

Moles of the acid that reacted are 0.0045 moles

Mass of the acid in 0.0045 moles is 0.1500 g

Therefore;

Molecular weight = mass ÷ moles

= 0.1500 g ÷ 0.0045 moles

= 33.33 g/mol

Therefore, the molecular weight of the acid in grams is 33.33 g