Unit 3 ~ Learning Guide Name:

Transcription

1 Unit 3 ~ Learning Guide Name: Instructions: Using a pencil, complete the following notes as you work through the related lessons. Show ALL work as is explained in the lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions if you don t understand anything! Please print out the Formula Sheet and found at the start of the course. You will need this to do assignments and tests! Solubility: 1. What is the difference between a homogeneous mixture and a heterogeneous mixture? 2. What do you think will happen if more solute is added to a saturated solution in flask? 3. What is the concentration we use to determine if a substance is soluble or insoluble in a solvent? 4. What is the equation for solubility(s) in relation to K sp for a 1:1:1 reaction? Rearrange this to determine the equation for K sp in terms of solubility (s). 5. What is the equation for solubility(s) in relation to K sp for a 1:2:1 or 1:1:2 reaction? Rearrange this to determine the equation for K sp in terms of solubility (s). 6. What is the equation for solubility(s) in relation to K sp for a 1:1:3 or 1:3:1 reaction? Rearrange this to determine the equation for K sp in terms of solubility (s). Page 1 of 10

2 7. Look up the K sp of strontium carbonate in your data booklet. Write the dissociation equation for this compound, determine what ratio it is and then calculate its solubility. 8. The K sp of Sc(OH) 3 is 8.0x Write the dissociation equation for this compound, determine what ratio it is and then calculate its solubility. 9. The solubility of NiS (s) is 5.5 x M at 25 C.Write the dissociation equation and calculate K sp. 10. The solubility of copper (II) hydroxide is 1.8 x 10-7 M at 25 C.Write the dissociation equation and calculate K sp. Page 2 of 10

3 11. A 500. L sample of saturated silver bromide is evaporated to dryness. What is the mass of the solid residue? 12. A 500. L sample of saturated copper(ii) iodate is evaporated to dryness. What is the mass of the solid residue? Page 3 of 10

4 13. A solution which contains only one of the following anions: I -, SO 4 2-, or OH - is tested with various reagents and the following results are obtained: Reagent Result 0.2M AgNO 3 Precipitate 0.2 M Fe(NO 3 ) 2 Precipitate 0.2 M Sr(NO 3 ) 2 No precipitate a) Which anion does the solution contain? b) Explain why each of the other two ions is not the ion in the solution. 14. A solution which contains only one of the following cations: Ag +, Pb 2+, or Cu + is tested with various reagents and the following results are obtained: Reagent Result 0.2M NaCl Precipitate 0.2 M Na 2 SO 4 No Precipitate 0.2 M NaNO 3 No precipitate a) Which cation does the solution contain? b) Explain why each of the other two ions is not the ion in the solution. Page 4 of 10

5 15. If 120. ml of M AgNO 3 and 70.0 ml of M K 2 CO 3 are combined, will a precipitate form? Use the table below to help you reach your answer. Start by filling in the correct dissociation equation for the possible precipitate. + [Initial] - [Trial] Given a M solution of KOH, what concentration of Mg(NO 3 ) 2 will be needed to just start precipitation of Mg(OH) 2? First write the dissociation equation for the precipitate then use the K sp equation for the precipitate. There is no dilution effect in this situation as the amount added is very small. Page 5 of 10

6 17. Fill in each box in the following table with either Increased solubility or Decreased solubility Reaction Type Temperature Increases Temperature Decreases Exothermic Endothermic 18. For the following equilibrium, determine whether adding each of the following compounds will increase solubility, decrease solubility or have no effect. CuCl 2(s) Cu 2+ (aq) + 2 Cl - (aq) Compound Added Effect on solubility of CuCl 2 NaCl Cu(NO 3 ) 2 CuCl 2 KI Saturated Solutions: 1. Explain why a saturated solution with NO solid present is NOT at equilibrium. 2. Which of the following saturated solutions will have the lowest [Ba 2+ ]? Explain how you know. Barium carbonate Barium chromate Barium sulphate Page 6 of 10

7 3. When do you stop adding solution from your burette when doing a titration? Ions: 1. When you are separating ions using filtration, what is the name of the solution that passes through the filter? 2. For each pair of ions given on the left, circle an ion which could be added in order to allow for separation of the ions on the left. Ions to be separated Circle the correct ion Cu + and Na + Cl - SO 4 2- NO 3 - Sr 2+ and Pb 2+ PO 4 2- SO 4 2- OH - S 2- and OH - Sr 2+ Mg 2+ Ag + 3. Write an equilibrium reaction for each precipitate that forms in question What concentration of silver bromate can dissociate in M sodium bromate? Page 7 of 10

8 5. What concentration of lead (II) iodide can dissociate in 3.00 M potassium iodide? 6. What concentration of iron (III) hydroxide can dissociate in 4.0 x10-12 M potassium hydroxide? 7. A large vessel contains 250. L of M barium sulfide (BaS). What mass of solid sodium carbonate (Na 2 CO 3 ) would be needed to just start precipitation of barium carbonate (BaCO 3 )? Page 8 of 10

9 8. A large vessel contains 500. L of M silver (I) nitrate (AgNO 3 ). What mass of solid ammonium chromate ((NH 4 ) 2 CrO 4 ) would be needed to just start precipitation of silver (I) chromate (Ag 2 CrO 4 )? Answers: Solubility Hints: 3. In your data booklet, look at the top of the Solubility of Common Compounds in Water Chart To calculate solubility you use roots. To calculate K sp you use powers Use the Solubility of Common Compounds in Water Chart. Precipitates form when a combination of ions results in low solubility. 15. Use the initial boxes to do a dilution calculation. Page 9 of 10

10 Solubility Answers: x10-5 M x10-8 M x x g g 15. Trial K sp = 5.73x x10-7 M Ions Hints: 2. Use the Solubility of Common Compounds in Water Chart. Precipitates form when a combination of ions results in low solubility The first step in each of these questions is to write a dissociation equation for whichever combination of ions is low solubility. The second step is to write a K sp equation. The third step is to plug in numbers for whatever you know and solve for what you don't! Ions Answers: M x10-10 M x g g Page 10 of 10