PSC 4012 Ionic Phenomena: A study of an environmental problem

PSC 4012: Dilution

Dilution Process of adding water to a solution to obtain desired concentration

PSC 4012: Dilution Dilution process: Start with stock solution (1) C 1 = n 1 / V 1 Add water to stock solution Obtain solution (2) C 2 = n 2 / V 2 n 1 = n 2 C 1 V 1 = C 2 V 2

PSC 4012: Dilution Calculations Sabrina must prepare a solution for a physical science experiment. What volume of the initial 20 g/L salt solution would she need to take in order to prepare 100 mL of a diluted solution with a concentration of 2 g/L? C 1 V 1 = C 2 V 2 V 1 = C 2 V 2 / C 1 V 1 = (2 g/L)(100ml)/20g/L V 1 = 10 ml

PSC 4012: Dilution Calculations Sabrina prepared 500 ml of a 2.5 mol/L solution of NaOH. The problem is that she forgot which of the three stock solutions she used. Knowing that she took only 250 ml, could you help her by pointing to the used stock solution? A: 1 MB: 3 MC: 5 M C 1 V 1 = C 2 V 2 C 1 = C 2 V 2 / V 1 C 1 = (2.5 M)(500ml)/250 ml C 1 = 5 M therefore C stock

PSC 4012: Dilution

PSC 4012: Stoichiometry Stoichiometric calculations Calculations of proportions in which chemicals combine in chemical reactions.

PSC 4012: Stoichiometry Stoichiometric calculations Three different scenarios: 1- Calculations involving number of moles 2- Calculations involving mass 3- Calculations combining number of moles and mass

PSC 4012: Stoichiometry Calculations involving number of moles Calculate the number of moles of oxygen that would react with sulphur dioxide to produce 10 moles of sulphur trioxide. First: write reaction Second: balance reaction Third: establish ratios 2SO 2 + O 2 → 2SO 3 SO 2 + O 2 → SO 3 1 mol O 2 = 2 mol SO 3 X = 10 mol SO 3 X = 5 mol O 2

PSC 4012: Stoichiometry

Calculations involving mass How much sulfuric acid (H 2 SO 4 ) can be produced from the reaction of 160.2g of sulphur trioxide with water. First: write reaction Second: balance reaction Third: establish ratios SO 3 + H 2 O → H 2 SO 4 1 mol SO 3 = 1 mol H 2 SO g SO 3 = 98.1 g H 2 SO g SO 3 = X X = g H 2 SO 4

PSC 4012: Stoichiometry

Calculations involving number of moles & mass How much oxygen is needed to burn 3 moles of methane (CH 4 ) and produce carbon dioxide and water? First: write reaction Second: balance reaction Third: establish ratios CH 4 + 2O 2 → CO 2 + 2H 2 O CH 4 + O 2 → CO 2 + H 2 O 1 mol CH 4 = 2 mol O 2 3 mol CH 4 = X X = 6 mol O 2 1 mol O 2 = 32g 6 mol O 2 = Y Y = 192g O 2

PSC 4012: Stoichiometry