GCSE chemistry chapter 8

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Kirby...
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Do I have to know what compounds and an-ions are found in a flame test? Based on each colour. Or do I just need to know which colour matches which cat-ion.
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515
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You will need to be able to know the ion that is burnt based on the colour of the flame AND the other way around.

Make sure you don't confuse yourself with anions and cations (which are the correct names, not an-ion and cat-ion)

Cations are positively charged and can be tested using the flame test and precipitation with Sodium Hydroxide.

Anions are negatively charged and can be tested in three ways:

To test for Carbonate ions, you add Dilute Acid and bubble through lime water, which will turn cloudy if carbonate ions are present.
To test for Sulphate ions, you add Hydrochloric acid and Barium Chloride, which will form a White Precipitate (An insoluble solid) of sulphate ions are present
To test for Halide ions, you add Nitrate Acid and Silver nitrate that will form:
A white precipitate if Chloride ions are present.
A cream precipitate if Bromide ions are present.
A yellow precipitate if Iodide ions are present.

I hope this helps.
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Kirby...
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#3
Report Thread starter 4 years ago
#3
(Original post by 515)
You will need to be able to know the ion that is burnt based on the colour of the flame AND the other way around.

Make sure you don't confuse yourself with anions and cations (which are the correct names, not an-ion and cat-ion)

Cations are positively charged and can be tested using the flame test and precipitation with Sodium Hydroxide.

Anions are negatively charged and can be tested in three ways:

To test for Carbonate ions, you add Dilute Acid and bubble through lime water, which will turn cloudy if carbonate ions are present.
To test for Sulphate ions, you add Hydrochloric acid and Barium Chloride, which will form a White Precipitate (An insoluble solid) of sulphate ions are present
To test for Halide ions, you add Nitrate Acid and Silver nitrate that will form:
A white precipitate if Chloride ions are present.
A cream precipitate if Bromide ions are present.
A yellow precipitate if Iodide ions are present.

I hope this helps.
Thank you.
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