Question

(8 pts) Carbon dioxide in the atmosphere dissolves in water to establish an equilibrium that can increase the acidity of aqueous solutions in the environment. This equilibrium is CO2(g) = CO2 (aq), Kn= 3.1 x 10-2 at 25°C. Kh is called the Henry's law constant, which relates the solubility of the gas CO2 in the aqueous solution, [CO2), to the partial pressure of CO2 over the solution, p(CO2): [CO2] (M)= Kn · p(CO2) (atm) During the preceding decades, the atmospheric concentration of CO2(g) has steadily increased, according to measurements at NOAA's Mauna Loa Observatory in Hawaii. (a) (2 pts) In Dec 2017, the mole fraction of CO2(g) was 405 ppm. What is the solubility (in M) of CO2(aq) in water at 25°C? You may assume the solution is in contact with air at 1.00 atm total pressure. (b) (6 pts) Assume that all of this CO2(aq) is in the form of carbonic acid, H2CO3(aq). Determine the pH of this aqueous solution by setting up an 1-C-E table. You may assume that H2CO3(aq) is just a monoprotic acid. Useful information is available in Appendix 5 of the textbook. (HINT: you should set up and solve a quadratic equation. – see Appendix 1 of the textbook) NOTE: the pH of the oceans has dropped approximately 0.1 pH units from 8.2 to 8.1 since the start of the industrial revolution, over 200 years ago. The pH values of freshwater lakes and ponds vary from 6-8, depending on the surrounding soil and bedrock, which contain carbonates and other basic salts.

Answer 1

a 400 per ppm 100 meons moles of Yos total moles gases of co in av. Pressure a moles of gas. yos lo x 1.00 atm 0.000 You atm. z [con) (nm) a Kr. ecco) z 3-1x10²x0-000405 2 1-26 x 6 m. Sowbility of co ? 11-3x 105 m in water at 25°C Now Chees) accord a 1-3x10 m. нсе, — нт +нсо, - I 1-3x10 m 101xx G 1-3x10 x x of Haco 2 4-2x107 - 2x107 (use value Can you book 6 use value and - Ka 2 Cht) [reon) Си, со 4.2x107 = x2 1-3x105 2) x² + 4.2x100 - 5.46x1012 20 using quadratic equation sover I get x 2.1 x 156 m = [Ht). =) pH e tog Cht) & log (2.1x1080) 2) PM 215-68)