Question

PLEASE MAKE SURE TO CALCULATE THE UNCERTAINTY!!

Practice Problem udent Suzie Q sets out to analyze an impure sample of potash (potassium hydroxide) for percent purity. Suzie Q will use an HCl solution that she standardizes with Na2CO3 If she weighs out a 0.562 g sample of potash, what is the percent purity (with uncertainty) based on the following information? MWKoH 65.1056 g/mol (negligible unc.) MWNzcos 105.98844 g/mol (negligible unc.) Stdzn of HCI SNazcos- 0.220 mIHa 35.22 Titn of KOH Uncertainties Balance-t 0.001g Buret t0.06 mL mLHc 40.36

Answer 1

The enthalpy change of reaction at unknown temperature is, Delta H_T (T_f) = Delta H^0 (T_i) + integral_T_i^T_f delta c_p_1j dT = Delta H^0 (T_i) + delta c_p_1i (T_f - T_i) rightarrow (1) The difference between constant pressure heat capacities of unfold and folded protein is Delta c_p_1 i = c_p_1 I (unfold) - c_p_1 I (folded) delta c_p_1 I = 6.28 kJ/mol k (given) The enthalpy change of reaction at 25 degree c is, delta H_T (25 degree C) = Delta H^0 (755 degree C) + Delta Cp_i I (25 degree C - 755 degree C) (From eq (1)) = 509 + 6.28 kj/ma.k (298 - 348.5 k^) = 509 + 6.28 kJ/ma.k (298 - 348.5 k^) = 509 - 317.14 Delta H_T = 191.8 kJ/mol. So, the entropy change of reaction at 25 degree c is delta s_t (25 degree C) = q/T = Delta H_T (25 degree c)/T (constant temperature) = 191.8 kj/mol/298 k = 0.643 kj/mol . k Delta S_T