Question

88. What volume of 0.921 M Na2CO3 solution contains 74.0 g of NazCO3? a. 0.642 L b . 8.52 * 10 L c.0.757 L d. 7.22 x 10'L e. 1.31 L 89. An aqueous nitric acid solution has a pH of 2.15. What mass of HNO is present in 20.0 L of this solution? a. 0.11g b. 0.022 g c. 3.7 g d. 6.8 g e. 8.9 g 90. The pH of purified water (or of a neutral solution) is . Indicate the answer choice that best completes the statement or answers the question. 91. The pH of an aqueous NaOH solution is 12.83. What is the hydrogen ion concentration of this solution? a. 1.5 x 10-'M 5.6.7 x 10-?M c. 1.2M d. 6.7 x 10.2 M c.2.7 x 10 M 92. What is the pH of 2.9 x 10- M HCl(aq)? a. -1.01 b. 2.54 c. 3.50 d. 1.01 e. 5.65 93. The pH of a vinegar solution is 4.15. What is the H30" concentration of the solution? a. 7.1 10M b.1.6 10-2M c. 0.62 M d. 1.4 M e. 1.4 x 10-M 04.10.1800 g of impure soda ash (Na2CO3) is titrated with 15.66 mL of 0.1082 M HCI, what is the percent purity of the soda ash? Na2CO3(aq) + 2 HCl(aq) + 2 NaCl(aq) + H2O(l) + CO2(g) a. 17.96% b. 49.89% c. 50.11% d. 94.13% e. 99.77% Page 12

Answer 1

The answer is option C (0.757 L)

We have to find the molecular weight of Mala Molecular weight of Sodium = 23 Molecular weight of Carbon = 12u Allerator weight . Atomic weight of Oxygen = 16u. Molecular weight of nlayn = (2x23)+ (12) + (3 416) B = lobu lobg of rla og is equal to 1 mote of Alaalla Weight of Mayoz given = 749. af lumber of moles of Alagz in Fleg = 74 = 0.698 model Прь — * This means that if thg of nao is dissolved in Ilitre of Soln, we get ole 0.698 Molar Sdn. We know that CVI = GV2 I G=Concentration of ft Solution I 5 = Concent satwo of Solution V,= Volume of ist Solution 1 ₂ - Volume of lind Solution. We take, G= 0.698M & Vi=12 given that ( = 0.921 M & V₂ = Un knowny. let's assume that I2 = X Littes by the formula, Cir= GV₂ 0.698x1 = 0.921% 94 - x = 0.757 Litres option c is the answeo.