Tests for Gasses and Ions knowledge test | GCSE AQA Triple Chemistry

Hey. This is a knowledge check to help you remember Tests for gasses, Flame tests, Test for ions in the Chemistry AQA Triple GCSE. Resources I used to make these cards are from the Oxford AQA revision guide and @Freesciencelessons on youtube : 

https://www.youtube.com/watch?v=3oJxWwcnfJY&list=PL9IouNCPbCxXlBeaxebOG5yf_pGrxzOyR

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Describe the test for Hydrogen gas
Hold a lighted splint near a tube of suspected Hydrogen gas. As the flame nears the mouth of the tube, a 'Squeaky pop ' noise should be heard if Hydrogen is present [Hydrogen burns rapidly in air producing the noise]
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Describe a test for Oxygen gas
Near a glowing splint near a test tube of suspected Oxygen. Splint should relight in the pre sence of Oxygen
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Describe a test for Carbon dioxide gas
Bubble the gas through limewater. Limewater will turn from colourless to cloudy if carbon dioxide is present
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Describe a test for chlorine
Hold the end of a litmus paper near the mouth of a test tube with suspected chlorine gas. The litmus paper should bleach from blue(or colour) to white if chlorine gas is present.
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What can some positive ions be tested by?
A flame test
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What colour is the flame for Lithium?
Crimson
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What colour is the flame for Potassium?
Lilac
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What colour is the flame for Copper?
Green
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What colour is the flame for Sodium?
Yellow
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What colour is the flame for Calcuim?
Orange - Red
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Why might sometimes the colours be difficult to see?
If there is a low concentration of the metal compound. If there is a mixture of other substances which could mask the colour.
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What do scientists use insted of flame tests?
Flame emmission spectroscopy (as flame tests are difficut to read properley)
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How does a Flame emmission spectrosopy work?
A sample of metal ion is held in a flame. The light given out by the flame is passed to a machiene called a spectroscope. This converts the light to a line spectrum
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How would you know if the concentration of the metal ion is high/low looking at the line spectrum?
The lines on the spectrum become more intense as the concentration gets higher.
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What does an instrumental method mean and why are instrumental methods better?
Instrumental methods are done by a machiene, they are more rapid, more specific and accurate & very sensitive (meaning they pick up more detail)
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What ions form white precipitates when sodium hydroxide is added? And how can you differentiate between them?
Calcuim, Magnesium and Aluminium ions. For calcium a flame test is needed, for aluminium if excess sodium hydroxide is added aluminium redissolves. Magnesium is not aluminium or calcium
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What happens to Copper (II) ions when sodium hydroxide is added?
A blue precipitate is formed, of Copper (II) Hydroxide
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What happens to Iron (II) ions when sodium hydroxide is added?
A green precipitate is formed, of Iron (II) hydroxide
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What happens to Iron (III) ions when sodium hydroxide is added?
A brown precipitate is formed, of Iron (III) Hydroxide
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How do you test for carbonate ions? [give in 3 steps]
1) Add dilute acid to the sample 2)Acid will react with carbonate to[possibly] form carbon dioxide gas, we can see this through fizzing. 3) Bubble gas through limewater to make sure it is carbon dioxide
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How would you start a test for halide ions?
1) Add dilute nitric acid to sample 2) Add dilute silver nitrate solution [this forms precipitates of halide ions]
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What colour is the precipitate for Bromide ions?
Cream precipitate
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What colour is the precipitate for Chloride ions?
White precipitate
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What colour is the precipitate for Iodide ions?
Yellow precipitate
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How would you test for Sulfate ions?
1) Add dilute hydrochloric acid to sample 2) Add barium chloride solution 3)If sulfate ions are present, white precipitates are formed
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Other cards in this set

Card 2

Front

Describe a test for Oxygen gas

Back

Near a glowing splint near a test tube of suspected Oxygen. Splint should relight in the pre sence of Oxygen

Card 3

Front

Describe a test for Carbon dioxide gas

Back

Preview of the front of card 3

Card 4

Front

Describe a test for chlorine

Back

Preview of the front of card 4

Card 5

Front

What can some positive ions be tested by?

Back

Preview of the front of card 5
View more cards

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