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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tahellemadenko01, let's knock this out. c) In one such titration exercise, the following results were obtained for the volume of the acid used. i) Complete the table and determine the mean titre. Step 1: Calculate the titre for each experiment. Titre = Final Burette Reading - Initial Burette Reading Approximate: 21.8 cm^3 - 0.0 cm^3 = 21.8 cm^3 Accurate 1: 21.5 cm^3 - 0.5 cm^3 = 21.0 cm^3 Accurate 2: 43.3 cm^3 - 22.3 cm^3 = 21.0 cm^3 Step 2: Complete the table. |l|c|c|c| & Approximate & Accurate 1 & Accurate 2 \\ Final Burette Reading & 21.8 cm^3 & 21.5 cm^3 & 43.3 cm^3 \\ Initial Burette Reading & 0.0 cm^3 & 0.5 cm^3 & 22.3 cm^3 \\ Titre & 21.8 cm^3 & 21.0 cm^3 & 21.0 cm^3 \\ Step 3: Determine the mean titre. The accurate titres are 21.0 cm^3 and 21.0 cm^3. The approximate titre is usually discarded. Mean titre = 21.0 cm^3 + 21.0 cm^32 = 42.0 cm^32 = 21.0 cm^3 ii) State a suitable indicator for this titration and the colour change at the end point of the titration. The titration is between a strong acid (HCl) and a strong base (NaOH). Indicator: Phenolphthalein* Colour change: Pink to colorless* (or colorless to pink, depending on which solution is in the flask. If acid is added to base, it goes from pink to colorless). d) Calculate the concentration of the hydrochloric acid, if the student used 25 cm^3 of 0.1 M NaOH solution for complete neutralization of the dilute HCl according to the reaction equation: NaOH(aq) + HCl(aq) → NaCl(aq) + H_2O(l) Step 1: Identify the known values. Concentration of NaOH (C_b) = 0.1 M Volume of NaOH (V_b) = 25 cm^3 = 0.025 dm^3 Volume of HCl (V_a) = Mean titre = 21.0 cm^3 = 0.021 dm^3 From the balanced equation, the mole ratio of HCl to NaOH (n_a:n_b) is 1:1. Step 2: Use the titration formula. (C_a V_a)/(n_a) = (C_b V_b)/(n_b) Where C_a is the concentration of HCl. Step 3: Substitute the values and solve for C_a. C_a × 0.021 dm^31 = 0.1 M × 0.025 dm^31 C_a = 0.1 M × 0.025 dm^30.021 dm^3 C_a = (0.0025)/(0.021) M C_a ≈ 0.1190476 M Rounding to three significant figures: 0.119 M e) A student was given the following mixtures. Complete the following table by suggesting a suitable method of separation. |l|l| Mixture & Method of separation \\ Ethanol/water & Fractional distillation \\ Solid NH_4Cl/NaCl & Sublimation \\ f) Identify the equipment that is used to protect the hands in the laboratory. Gloves Got more? Send 'em!