FORMULA SHEET (tear off), Exercises of Chemistry

Download FORMULA SHEET (tear off) and more Exercises Chemistry in PDF only on Docsity! FORMULA SHEET (tear off) NA = 6.022 x 1023 C = (5/9) (F - 32) F = (9/5)(C) + 32 1 amu = 1.661 x 10-27 kg C = K - 273.15 K = C + 273.15 1 atm = 760 torr = 760 mm Hg 1 atm = 1.013 bar pV = nRT R = 0.08206 Latm/molK 1 Latm = 101.3 J R = 8.314 J/molK 1 J= 1 kgm2/s2 pA = XA pA [B] = k pB pA = XBpA Tb = Kb mB Tf = Kf mB  = [B]RT H = U + pV G = H - TS Grxn = Grxn + RT ln Q ln K = - Grxn/RT Kp = KC (RT)n If ax2 + bx + c = 0, then x = ( - b  [b2 - 4ac]1/2 ) 2a KaKb = Kw = 1.0 x 10-14 (at T = 25C) pH = pKa + log10{[base]/[acid]} 2 GENERAL CHEMISTRY 2 THIRD HOUR EXAM Name ________________________________________________ Panthersoft ID ________________________________________________ Signature ________________________________________________ Part 1 ________________ (20 points) Part 2 ________________ (22 points) Part 3 ________________ (38 points) TOTAL ________________ (80 points) . Do all of the following problems. Show your work. 5 Part 3. Problems. 1) Propanoic acid (CH3CH2COOH, MW = 74.08 g/mol) is a weak monoprotic acid, with Ka = 1.34 x 10-5. a) A chemist prepares 1.000 L of a 0.0360 M aqueous solution of propanoic acid. What is the pH of the solution? [12 points] b) 0.500 g of sodium hydroxide (NaOH, MW = 40.00 g/mol) is added to the above 1.000 L solution of propanoic acid. What is the new value for pH after the addition of the sodium hydroxide? You may assume that the addition of NaOH does not change the volume of the solution. [12 points] 6 2) A 25.00 mL sample of an aqueous stock solution of potassium hydroxide (KOH, MW = 56.11 g/mol) is titrated with a 0.2281 M aqueous solution of hydrochloric acid (HCl, MW = 36.46 g/mol) at T = 25. C. After the addition of 23.04 mL of the HCl solution the equivalence point for the titration is reached. a) What is the concentration of the stock solution of potassium hydroxide? [10 points] b) What is the pH at the equivalence point of the titration (circle the correct answer)? [4 points] greater than 7.0 equal to 7.0 less than 7.0