A 10.0 ml sample of vinegar which is an aqueous solution of acetic acid, requires 16.5ml of a 0.500M NaOH solution to reach the endpoint in a titration (where the moles of acid are equal to the moles of base). What is the molarity of the acetic acid solution?

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To determine the molarity of the acetic acid solution, we can use the concept of stoichiometry in a titration.

Here's how you can calculate the molarity of the acetic acid solution:

1. Write the balanced chemical equation for the reaction between acetic acid (CH3COOH) and sodium hydroxide (NaOH):
CH3COOH + NaOH → CH3COONa + H2O

2. Determine the stoichiometry of the equation. From the balanced equation, we can see that 1 mole of acetic acid reacts with 1 mole of sodium hydroxide.

3. Calculate the number of moles of NaOH used in the titration:
Moles of NaOH = Molarity of NaOH × Volume of NaOH used (in liters)
Moles of NaOH = 0.500 M × 0.0165 L = 0.00825 moles

4. Since the reaction between acetic acid and NaOH has a 1:1 ratio, the number of moles of acetic acid is also 0.00825 moles.

5. Calculate the molarity of the acetic acid solution:
Molarity of acetic acid = Moles of acetic acid / Volume of acetic acid (in liters)
Volume of acetic acid = 10.0 mL = 0.0100 L
Molarity of acetic acid = 0.00825 moles / 0.0100 L = 0.825 M

Therefore, the molarity of the acetic acid solution is 0.825 M.