A solution of volume 0.500 L contains 1.68 g NH3 and 4.05 g (NH4)2SO4. N: 14, H:1, S:32, O:16 g/mol, Kb = 1,8x10-5, Kw = 1x10-14 (NH4)2SO4 + H2O → 2NH4+(aq) + SO4-2(aq) (a) What is the p H of this solution? (b) What is the pH after the addition of 0.0050 mol HCl(aq)? (c) What would be the pH after the addition of 0.0050 mol NaOH to the original buffer? (Assume that the volume remains 0.500 L.)

4- 30- [14] How many liters of the antifreeze ethylene glycol (HOCH₂CH₂OH, 54.09 g/mol) would you add to a car-radiator containing 6.50 L of water to keep it from freezing if the coldest winter temperature in your area is -20°C? Calculate the boiling point of this water-ethylene glycol mixture. (The density of ethylene glycol is 1.11 g/mL, the molal freezing and boiling point constants are respectively kf = 1.86°/m and kb= 0.52 °/m). & Page 5

Excess calcium carbonate reacts with 150. mL of 0.250 M H3PO4(aq) according to the reaction below.           CaCO3(s)      +      H3PO4(aq)        ?          CO2(g)      +       H2O(l)         +        Ca3(PO4)2(aq))            (unbalanced)       How many milliliters of carbon dioxide are formed at STP?

A)What is the H+H+ concentration for an aqueous solution with pOHpOH = 3.54 at 25 ∘C∘C? Express your answer to two significant figures and include the appropriate units. b)At a certain temperature, the pHpH of a neutral solution is 7.49. What is the value of KwKw at that temperature? Express your answer numerically to two significant figures. c) answer the attached image