This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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To solve this problem, we must first make an assumption for the average volume of acid A (HY) used in the titration, as the experimental procedure in part (a) was not performed. Assumption for part (a): We assume that 25.00 cm³ of NaOH solution (B) was titrated with acid HY (A). Let the average volume of acid A (HY) used from the burette be 24.50 cm^3. Given information: • Mass of HY dissolved to make 250 cm³ solution = 1.64 g • Concentration of NaOH solution (B) = 0.100 mol dm⁻³ • Volume of NaOH solution (B) used = 25.00 cm³ • Reaction: HY_(aq) + NaOH_(aq) NaY_(aq) + H_2O_(l) • Relative atomic masses: H = 1.0, O = 16.0, Na = 23.0 b) From your results and the information provided, calculate the: Step 1: Calculate the moles of NaOH used. The concentration of NaOH is given, and the volume used is the pipette volume. Moles of NaOH = Concentration of NaOH × Volume of NaOH n_NaOH = 0.100 mol dm^-3 × ((25.00)/(1000)) dm^3 n_NaOH = 0.100 mol dm^-3 × 0.02500 dm^3 = 0.002500 mol Step 2: Determine the moles of HY that reacted. From the balanced chemical equation, the mole ratio of HY to NaOH is 1:1. n_HY = n_NaOH = 0.002500 mol Step 3: Calculate the concentration of A (HY) in mol dm⁻³. This is the concentration of the acid in the burette, using the assumed average titre volume. Concentration of HY = Moles of HYVolume of HY used C_HY = 0.002500 mol((24.50)/(1000)) dm^3 C_HY = 0.002500 mol0.02450 dm^3 = 0.10204 mol dm^-3 Rounding to three significant figures: Concentration of A (HY) = 0.102 mol dm^-3 Step 4: Calculate the concentration of A (HY) in g dm⁻³. The acid HY was prepared by dissolving 1.64 g in 250 cm³ of solution. Concentration of HY in g dm^-3 = Mass of HYVolume of solution Concentration of HY in g dm^-3 = 1.64 g((250)/(1000)) dm^3 Concentration of HY in g dm^-3 = 1.64 g0.250 dm^3 = 6.56 g dm^-3 Concentration of A (HY) = 6.56 g dm^-3 Step 5: Calculate the molar mass of the acid HY. The molar mass can be found by dividing the concentration in g dm⁻³ by the concentration in mol dm⁻³. Molar mass of HY = Concentration of HY in g dm^-3Concentration of HY in mol dm^-3 M_HY = 6.56 g dm^-30.10204 mol dm^-3 = 64.288 g mol^-1 Rounding to three significant figures: Molar mass of HY = 64.3 g mol^-1 *c