Respuesta :
Answer:
5.42%
Explanation:
Let's consider the neutralization reaction between NaOH and acetic acid.
NaOH(aq) + CH₃COOH(aq) → CH₃COONa(aq) + H₂O(l)
It took 22.15 mL of 0.0981 M NaOH(aq) to reach the faint pink endpoint. The reacting moles of NaOH are:
0.02215 L × 0.0981 mol/L = 2.17 × 10⁻³ mol
The molar ratio of NaOH to CH₃COOH is 1:1. The reacting moles of CH₃COOH are 2.17 × 10⁻³ moles.
The molar mass of acetic acid is 60.05 g/mol. The mass of acetic acid is:
2.17 × 10⁻³ mol × 60.05 g/mol = 0.130 g
0.130 g of acetic acid are in a 2.40 g sample of vinegar. The percent by mass of acetic acid in vinegar is:
0.130 g/2.40 g × 100% = 5.42%
Answer:
The mass % of acetic acid is 5.42 %
Explanation:
Step 1: Data given
Mass of sample of vinegar = 2.40 Grams
Volume of water = 100 mL = 0.100 L
Volume of NaOH = 22.15 mL = 0.02215 L
Molarity of NaOH = 0.0981 M
Step 2: The balanced equation
NaOH (aq) + CH3COOH (aq) ⇆ CH3COO–Na+ (aq) + H2O (l)
Step 3: Calculate moles NaOH
Moles NaOH = molarity * volume
Moles NaOH = 0.0981 M * 0.02215 L
Moles NaOH = 0.00217 moles
Step 4: Calculate molesCH3COOH
For 1 mol NaOH we need 1 mol CH3COOH to produce 1 mol CH3COONa and 1 mol H2O
For 0.00217 moles NaOH we need 0.00217 moles CH3COOH
Step 5: Calculate mass CH3COOH
Mass CH3COOH = moles CH3COOH * molar mass CH3COOH
Mass CH3COOH = 0.00217 moles * 60.05 g/mol
Mass CH3COOH = 0.130 grams
Step 6: Calculate mass % of acetic acid
Mass % = (0.130 grams / 2.40 grams) * 100 %
Mass % = 5.42 %
The mass % of acetic acid is 54.2 %