GCSE Edexcel Chemistry (Qualitive Chemistry)

GCSE Edexcel Chemistry (Qualitive Chemistry)

Explain why the test for any ion must be unique

It would be impossible to distinguish specific ions if more than one test gave the same result

Describe a flame test to test for metal cations (5)

- Clean nichrome wire with HCl
- Dissolve some salt in HCl
- Dip wire into salt solution
- Hold wire in blue roaring flame above the inner cone
- Observe colour change

Describe a positive flame test for a Lithium ion, Li+

Flame turns Red

Describe a positive flame test for a Sodium ion, Na+

Flame turns Yellow

Describe a positive flame test for a Pottasium ion, K+

Flame turns Lilac

Describe a positive flame test for a Calcium ion, Ca2+

Flame turns orange - red

Describe a positive flame test for a Copper ion, Cu2+

Flame turns blue - green

Describe an NaOH test to test for metal cations (4)

- Place approx. 2cm of salt solution in test tube
- Add a few drops of NaOH solution
- Observe participate
- If white ppt, add excess NaOH to see if it re-dissolves

Describe a positive NaOH test for a Calcium ion, Ca2

White precipitate forms - remains when excess NaOH added

Describe a positive NaOH test for an Aluminium ion, Al3+

White precipitate forms - re-dissolves when excess NaOH added