2. Cu 1+ Cu 2+ MnO 4 1- CrO 4 2- Cr 2 O 7 2-

3. The presence of different ions in aqueous solution can be identified in a number of ways. One method is to add a soluble ionic substance which combines with the unknown ion and forms an insoluble precipitate. The simplest method is by colour.

4. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless

5. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it?

6. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless copper (II) sulfite sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it? solution ?

7. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it? sodium dichromate solution ?

8. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it? nickel(II) nitrate solution ?

9. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it? potasssium chromate solution ?

10. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it? sodium permanganate solution ?

11. IonColour of Solution Cr 3+ (aq) Cr 2+ (aq) Co 2+ (aq) Cu 2+ (aq) Cu 1+ (aq) Fe 3+ (aq) Fe 2+ (aq) Mn 2+ (aq) Ni 2+ (aq) CrO 4 2- (aq) Cr 2 O 7 2- (aq) MnO 4 -1 (aq) green blue pink blue green yellow-brown pale-green pale pink green yellow orange purple See page 341 groups 1,2,17 are colourless sodium dichromate potassium chloride sodium permanganate nickel(II) nitrate copper(II)sulfite potassium chromate which is it? potassium chloride solution ?

12. Try Practice questions 1-4 pg 342 Flame tests can also be used to identify different ions in solution

14. If a solution contains more than 1 ion, these ions can be removed 1 at a time if the right solutions are added in the right sequence. Suppose a solution was thought to contain both Ag 1+ (aq) and Pb 2+ (aq). If a solution containing Cl 1- (aq) was added it would precipitate out both ions at the same time. How could one of these ions be removed without removing the other? Look for an anion which precipitates out only one of them.

15. page 324 An excess of acetate ion, C 2 H 3 O 2 1- (aq), removes only Ag 1+ (aq) so any soluble salt containing this ion, NaC 2 H 3 O 2 (aq),for instance, can be used to get rid of all the silver.

16. solution thought to contain Ag 1+ (aq) and Pb 2+ (aq) add NaC 2 H 3 O 2 (aq) precipitate of AgC 2 H 3 O 2 (s) no precipitate of Ag 1+ (aq) filter add NaCl precipitate of PbCl 2 (s) no precipitate of Pb 2+ (aq) filter

17. Try investigation 7.5.1 pg. 345 Practice questions pg 346 #5,7,8,9.