Name: Chapter 3 The Mole & Stoichiometry Scientific Notation and Significant Figures Practice Problems 1. Rewrite the following numbers in scientific notation. a) 2300 b) 5601 c) 0.00026 d) 0.45013 e) 0.25 f) 0.037 g) 5000 h) 10005 2. Rewrite the following numbers in decimal notation. a) 3.75 x 10-2 b) 3.75 x 10 2 c) 4.056 x 10 4 d) 3.00 x 10 8 e) 1.5 x 10 3 f) 1.5 x 10-3 g) 1.2 x 10 4 h) 2.2 x 10 5 3. Determine the number of significant figures in the following measurements. a) 4050.0 b) 3.350 c) 405 d) 0.500 e) 300.0 f) 0.0202 g) 1.0 h) 1005 i) 1003 j) 3600.0 k) 0.0360 l) 10.000360 m) 0.02 n) 50.04 o) 30.20 p) 900.0 q) 324.009 r) 0.50 s) 1030 t) 1.005 4. Round the following to the correct number of significant figures: a) 3.45 to 2 sig figs f) 0.87333 to 2 sig figs b) 0.2495098 to 1 sig fig g) 601.92 to 4 sig figs c) 0.2814649 to 3 sig figs h) 11.86 to 3 sig figs d) 8.9483 to 2 sig figs i) 58.319 to 3 sig figs e) 29.97 to 3 sig figs j) 345.37 to 4 sig figs
5. Round the following to the correct number of significant figures. Remember to keep the same number of digits before the decimal place. a) 14 to 1 sig fig 14 to 3 sig figs b) 498 to 1 sig fig 498 to 2 sig figs c) 739 to 1 sig fig 739 to 2 sig figs d) 3689 to 1 sig fig 3689 to 2 sig figs e) 3689 to 3 sig figs 3689 to 4 sig figs f) 50915 to 1 sig fig 50915 to 2 sig figs g) 50915 to 3 sig figs 50915 to 4 sig figs 6. Add or subtract the following numbers, maintaining the correct number of decimal places in the final answer. 1) 4.60 + 3 = 2) 0.008 + 0.05 = 3) 22.4420 + 56.981 = 4) 200-87.3 = 5) 67.5-0.009 = 6) 71.86-13.1 = 7) 357.89 + 0.002 = 8) 17.95 + 32.42 + 50 = 9) 5.5 + 3.7 + 2.97 = 10) 84.675-3 = 11) 75-2.55 = 12) 10-9.9 = Answers 1) 8 2) 0.06 3) 79.423 4) 113 5) 67.5 6) 58.8 7) 357.89 8) 100 9) 12.2 10) 82 11) 72 12) 0 7. Multiply or divide the following numbers, maintaining the correct number of significant figures in the final answer. 1) 13.7 x 2.5 = 2) 200 x 3.58 = 3) 0.00003 x 727 = 4) 50.0 x 2.00 = 5) 2.3 x 3.45 x 7.42 = 6) 1.0007 x 0.009 = 7) 5003 / 3.781 = 8) 89 / 9.0 = 9) 5000 / 55 = 10) 51 / 7 = 11) 208 / 9.0 = 12) 0.003 / 5 = Answers 1) 34 2) 700 3) 0.02 4) 1.00 x 10 2 5) 59 6) 0.009 7) 1323 8) 9.9 9) 90 10) 7 11) 23 12) 0.0006
Dimensional Analysis Practice 1 kg = 1000 g 1 km = 1000 m = 0.62137 mi 1 mi = 1.6093 km 1 cm = 0.01 m = 0.39370 in. 1 in. = 2.54 cm 1 mg = 0.001 g 1 mm = 0.001 m 1 mg = 0.001 g 1 lb = 453.59 g 1 ml = 0.001 L 1 cm 3 = 1 ml 0 K = -273.15 ºC 1. 40 ml to L 8. 425 cm to km 2. 5400 L to ml 9. 544 ml to L 3. 85 g to kg 10. 74 cm to mm 4. 52 mg to g 11. 835 mg to kg 5. 6300 m to km 12. 115 lb to g 6. 2.50 kg to g 13. 45 m/s to km/h 7. 18 600 g to kg 14. 10 mi/h to m/s
Name: Chapter 3 The Mole Conversions Using Moles, Particles, and Litres Practice Problems 1. Name the object involved in the following measurements (atom, molecule, or ion) of each of the following substances. a. 1 mol Cu = 6.02 x 10 23 of Cu. b. 1 mol H2 = 6.02 x 10 23 of H2. c. 1 mol Fe(OH)2 = 6.02 x 10 23 of Fe(OH)2. d. 1 mol CO3 2- = 6.02 x 10 23 of CO2 2-. 2. Find the number of objects (atoms, molecules, or ions) in each of these substances. a. 5.00 mol Fe b. 0.200 mol NaI c. 34.0 mol SO3 d. 5.25 x 10-4 mol K2S e. 0.750 mol Zn f. 0.400 mol N2O5
3. Convert the following amounts into moles. a. 6.02 x 10 22 molecules Br2 b. 4.81 x 10 24 atoms Li c. 1.50 x 10 23 molecules NH3 d. 1 billion (1.0 x 10 9 ) molecules of O2 e. 1.20 x 10 25 atoms of P 4. For a e, convert the volumes into moles. For f j, determine the volume (L). Hint: If the volumes are given in ml, you must first convert to L (1 L = 1000 ml). a. 10 L of N2O4 f. 2.4 mol of CO2 b. 0.01 L of CCl4 g. 0.01 mol of BF3 c. 7.5 L of PCl5 h. 75 mol of Cl2 d. 23.5 L of C2H6 i. 250 mol of O2 e. 250 ml of O3 j. 25.9 mol of CH4
5. Determine the mass (in grams) of the following compounds. Sample: 3.9 mol NaOH (molar mass of NaOH = 40.00 g/mol) 3.9 mol NaOH ( ) ( 40.00 g ) = 156 (fix s. f. ) = 160 g NaOH 1 1 mol a. 14.7 mol Cu2SO4 f. 1.5 mol CuSO4 b. 1.4 mol CCl4 g. 0.02 mol AgI c. 3.5 x 10-3 mol PCl5 h. 1.0 x 10 2 mol NaCl d. 0.9 mol SO2 i. 4.08 mol Fe(NO3)2 e. 7.2 mol (NH4)2SO4 j. 1.0 x 10-4 mol MgO 6. Determine the number of moles of each of the following. Sample: 34.8 g KI (molar mass of KI = 166.0 g/mol) 34.8 g KI ( ) ( 1 mol ) = 0.20963 (fix s. f. ) = 0. 210 mol KI 1 166.00 g a. 166 g Cu3PO4 f. 205 g H2O (ice) b. 1.4 g CF4 g. 108.5 g C6H12O6 c. 10.72 g PCl5 h. 10.15 g LiF
d. 32.5 g AgNO3 i. 22.45 g CuCl e. 46.3 g CaCl2 j. 1.0 x 10 2 g NaOH Multi-step conversions: 7. Determine the number of atoms or molecules in each of the following. Hint: Remember to use the following conversions where needed: a. 14 g Fe ( 22.4 L 1 mol ) or (6.02 x 1023 particles ) 1 mol b. 55.6 g MgO c. 25.0 L C2H6 (at STP) d. 100.0 ml H2O2 (at STP) e. 950 mg C7H5N3O6 (TNT)
Molarity & Dilutions Calculations Practice Problems Section 1: M = mol L 1. If 2.00 mol of glucose is dissolved in 5.00L of water, what is the concentration? 2. If 5.50 mol of barium hydroxide is dissolved in 0.500 L of water, what is the concentration? 3. A salt solution has a volume of 250 ml and contains 0.70 mol of NaCl. What is the concentration of the solution? 4. How many moles of Na2SO4 are in 1.5 L of a 0.20 mol/l Na2SO4 solution? 5. How many moles of CaCl2 are in 250 ml of a 2.00 mol/l CaCl2 solution? 6. How many moles of HCl are in 50 ml of a 13.0 M HCl solution? 7. How many litres of water are needed to make a 5.00 M solution that has 15.0 mol of NaCl in it? 8. How many litres of water are needed to make a 3.0 M solution that has 50.0 mol of KOH in it? 9. Determine the concentration/molarity of a solution containing: a) 20.0 g of sodium chloride in 0.850 L of solution. b) 20.0 g of NaOH in 2.00 L of solution.
10. Calculate the mass (in grams) of solute required to prepare the following solutions: a) 0.25 L of a 2.5 mol/l potassium chloride solution. b) 4.20 L of a 0.100 mol/l solution of hydrochloric acid (HCl). 11. How many litres of 1.5 M solution can be prepared from 388.4 g of K2CrO4? Section 2: C 1 V 1 = C 2 V 2 1. How much 2.5 M NaCl solution would you need to make 300 ml of 0.50 M NaCl solution? 2. How much 0.25 M glucose (C6H12O6) solution can be made from 75.0 ml of 0.50 M glucose solution? 3. What would be the concentration of a solution made by diluting 35.5 ml of 2.25 M NaOH to 255 ml? 4. What would be the concentration of a solution made by adding 125 ml of water to 40.0 ml of 2.0 M KOH?
Name: Chapter 3 The Mole & Stoichiometry Assignment 1 Molar Conversions & Molarity/Dilutions Use significant figures and please circle or box off your answers. Show your work. /32 Section 1: Molar Conversions Marking: 3 marks for each question Dimensional analysis is set-up correctly/units are reported correctly Answer is calculated correctly Answer is reported to the correct number of significant figures /15 1. How many molecules are in 25 g of NH3? 2. How many grams are in 2.3 x 10 24 atoms of silver? 3. What volume (in L) would 1.204 x 10 24 particles take up? 4. How many molecules are in 56.0 L of H2O? 5. How many grams are in 20.4 L of CO2? 6. What volume (in L) would 125 g of CaCl2 take up? 7. How many molecules are present in 152 g CaCO3? 8. How many grams are present in 3.3 x 10 23 molecules of N2I6?
9. How many grams are present in 500.0 ml of CO2? 10. How many molecules are present in 578.0 mg of NaOH? Section 2: Molarity 1. If 13.5 mol of NaCl is dissolved in 14.76 L of water, what is the molarity? /11 2. How many litres of water are needed to make a 1.2 M solution that contains 12.5 g of MnSO4? 3. What is the molarity of a solution prepared by dissolving 15.0 g of solid sodium hydroxide pellets in 200.0 ml of water? 4. How much C6H12O6 (g) is needed to make 200.0 ml of a 0.50 M C6H12O6 solution? Section 3: Dilutions 1. What would be the concentration of a solution made by adding 22 ml of water to 45.0 ml of 1.4 M Ca(OH)2? /6 2. How much 0.500 M sulfuric acid solution can be made from 50.0 ml of 12.0 M sulfuric acid solution?