The molarity of citric acid in the lemon juice is 0.2923 M. To find the mass of citric acid in 0.100 L of juice, we calculate the mass for 25.00 mL and scale up, resulting in 5.616 grams of citric acid in 0.100 L of juice.
To calculate the molarity of citric acid in lemon juice from a titration with NaOH, we can first determine the moles of NaOH used. Since citric acid is a triprotic acid (tricarboxylic acid), each molecule can neutralize three hydroxide ions. The neutralization reaction is:
Citric Acid + 3NaOH → Sodium Citrate + 3H2O
Step 1: Find moles of NaOH used.
Moles of NaOH = Volume (L) × Molarity (M) = 0.02426 L × 0.904 M = 0.02192 moles
Step 2: Because one mole of citric acid reacts with three moles of NaOH, the moles of citric acid is one third of the moles of NaOH.
Moles of citric acid = Moles of NaOH / 3 = 0.02192 moles / 3 = 0.007307 moles
Step 3: Calculate molarity of citric acid.
Molarity of citric acid = Moles of citric acid / Volume of juice (L) = 0.007307 moles / 0.025 L = 0.2923 M
Step 4: Calculate the mass of citric acid in 0.100 L of juice.
Mass = Moles of citric acid × Molar mass of citric acid = 0.007307 moles × 192.12 g/mol = 1.404 g
Since we calculated the moles for 25.00 mL, we need to scale up to 100 mL (0.100 L).
Mass in 0.100 L = 1.404 g × 4 = 5.616 g