Chemical Analysis Activity Sheet One – Introduction/Revision Question 1 Indicate how many significant figures there are in: a) 0.3050 b) 0.003050 c) 1.003 × 104 Question 2 Round each number as indicated: a) 5.124 8 to 4 significant figures d) 0.135 237 1 to 4 significant figures b) 5.124 4 to 4 significant figures e) 1.525 to 3 significant figures c) 5.124 5 to 4 significant figures f) 1.525 007 to 3 significant figures Question 3 Write each answer with the correct number of digits: a) 3.021 + 8.99 = d) 0.0302 ÷ (2.1143 × 10-3) = b) 12.7 – 1.83 = e) log (2.2 × 10-18) = g) 10-4.555 = c) 6.345 × 2.2 = f) antilog (–2.224) = Question 4 Find the absolute and percent relative uncertainty and express each answer with a reasonable number of significant figures. a) 3.4 (±0.2) + 2.6 (±0.1) = b) [3.4 (±0.2) × 10-8] ÷ [2.6 (±0.1) × 103] = c) 3.4 (±0.2) ÷ 2.6 (±0.1) = d) [3.4 (±0.2) – 2.6 (±0.1)] × 3.4 (±0.2) = Question 5 a) A solution is prepared by dissolving 0.2222 (±0.0002) g of KIO3 [FM 214.0010 ±0.0009] in 50.00 (±0.05) mL. Find the molarity and its uncertainty with an appropriate number of significant figures. b) Would the answer be affected significantly if the reagent were only 99.9% pure? Question 6 Calculate the pH of a) 5.0 × 10-4 M HNO3 and b) 5.0 × 10-4 M (CH3)4N+OH-. Question 7 Using activity coefficients correctly, calculate the pH of a) 0.050 M HBr b) 0.050 M NaOH Question 8 Find the pH and fraction of dissociation (α) of a 0.010 0 M solution of the weak acid HA with Ka = 1.00 × 10-4. Question 9 A 0.100 M solution of the weak acid HA has a pH of 2.36. Calculate pKa for HA. Question 10 Calculate the concentration of Tl+ in a saturated solution of TlBr in water (Ksp = 3.7 x 10-9). Include activity effects. a) Calculate the concentration of Tl+ in a saturated solution of TlBr in 0.9 % w/v NaCl solution. Include activity effects. b) Comment on the difference between you answers to a) and b) above.