Chemistry Topic 9 Test for ions

9.1C Explain why the test for any ion must be unique

You would never be able to know which specific ion it was if more than one ion gave the same result.

9.2C Describe flame tests to identify the following ions in solids: a lithium ion, Li+

lithium - red

9.2C Describe flame tests to identify the following ions in solids:

b sodium ion, Na+

sodium - yellow

9.2C Describe flame tests to identify the following ions in solids:

c potassium ion, K+

potassium - lilac

9.2C Describe flame tests to identify the following ions in solids:

d calcium ion, Ca2+

calcium - orange-red

9.2C Describe flame tests to identify the following ions in solids:

e copper ion, Cu2+

copper - blue-green

9.3C

Metal hydroxides are insoluble so they precipitate out of solution when formed.

9.3C Describe tests to identify the following ions in solids or solutions as appropriate:

a aluminium ion, Al3+

using sodium hydroxide solution

1.Add sodium hydroxide solution.

2. The precipitate would be a white at first, then it would redissolve in excess NaOH to form a colourless solution.

9.3C Describe tests to identify the following ions in solids or solutions as appropriate:

b calcium ion, Ca2+

using sodium hydroxide solution

1. Add sodium hydroxide solution.

2. The precipitate would be white.

9.3C Describe tests to identify the following ions in solids or solutions

as appropriate:

c copper ion, Cu2+

using sodium hydroxide solution

1. Add sodium hydroxide solution.

2. The precipitate would be bue

9.3C Describe tests to identify the following ions in solids or solutions as appropriate:

d iron(II) ion, Fe2+

using sodium hydroxide solution

1. Add sodium hydroxide solution.

2. The precipitate would be green.

9.3C Describe tests to identify the following ions in solids or solutions

as appropriate:

e iron(III) ion, Fe3+

using sodium hydroxide solution

1. Add sodium hydroxide solution.

2. The precipitate would be brown.

9.3C Describe tests to identify the following ions in solids or solutions

as appropriate:

f ammonium ion, NH4+

using sodium hydroxide solution

1. Add sodium hydroxide solution.

2. If ammonia gas is given off, there are ammonium ions.

9.4C Describe the chemical test for ammonia

- Holding a damp piece of red litmus paper over it.

- IF AMMONIA: litmus will turn blue.

9.5C Describe tests to identify the following ions in solids or solutions as appropriate:

a carbonate ion, CO32-, using dilute acid and identifying the carbon dioxide evolved

- Add dilute acid

- The mixture will fizz and produce carbon dioxide.

If carbon dioxide:

- Add limewater

- Limewater goes cloudy

9.5C Describe tests to identify the following ions in solids or solutions as appropriate:

b sulfate ion, SO42-, using dilute hydrochloric acid and barium chloride solution

- Add dilute hydrochloric acid

- Add barium chloride solution

- A white precipitate will form.

9.5C Describe tests to identify the following ions in solids or solutions as appropriate:

c chloride ion, Cl- using dilute nitric acid and silver nitrate solution

- Add dilute nitric acid and drops of silver nitrate.

- A white precipitate of silver chloride will form.

9.5C Describe tests to identify the following ions in solids or solutions as appropriate:

c bromide ion, Br- using dilute nitric acid and silver nitrate solution

- Add dilute nitric acid and drops of silver nitrate.

- A cream precipitate of silver bromide will form.

9.5C Describe tests to identify the following ions in solids or solutions as appropriate:

c iodide ion, I- using dilute nitric acid and silver nitrate solution

- Add dilute nitric acid and drops of silver nitrate.

- A yellow precipitate of silver iodide will form.

9.7C Identify the ions in unknown salts, using results of the tests above

9.8C Describe that instrumental methods of analysis are available and that these may improve sensitivity, accuracy and speed of tests

Instrumental methods of analysis are available and can improve sensitivity, accuracy and the speed of tests.

(gas chromatography & mass spectometry)

9.9C Evaluate data from a flame photometer:

a to determine the concentration of ions in dilute solution using a calibration curve

b to identify metal ions by comparing the data with reference data

(no knowledge of the instrument or how it works is required)