A student found a 500 cm3 sample of vinegar. Knowing that vinegar is a solution of ethanoic acid (CH3COOH) and water, this student decided to take a 25.0 cm3 sample, dilute it with 25.0 cm3 of water and then react it with sodium hydroxide. The dilute sample required 37.0 cm3 of 0.850 mol dm–3 sodium hydroxide solution to react entirely with it via the following reaction:

CH3COOH(aq) + NaOH(aq) → NaCH3COO(aq) + H2O(l)

Calculate the concentration of ethanoic acid in the original sample of vinegar.