Test for Ions Flashcards

1
Q

What acid is used to detect carbonates?

A

A dilute acid such as hydrochloric acid.

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2
Q

What will happen if a dilute acid is added to a carbonate?

A

Carbon dioxide will be released as bubbles or fizz.

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3
Q

How do you test for carbon dioxide?

A

Limewater will turn cloudy in the presence of CO2.

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4
Q

How do you use the limewater to test for CO2?

A

Bubble the gas released through a test tube of limewater.

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5
Q

What is the equation for the reaction of a carbonate and an acid?

A

CO3^3-(s) + 2H+(aq) = CO2(g) + H2O(l)

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6
Q

How do you test for sulfates?

A

Add dilute HCl followed by barium chloride solution.

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7
Q

Which sulfate is insoluble in water?

A

Barium sulfate

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8
Q

What will happen if a sulfate is present?

A

You will get a white precipitate.

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9
Q

What sulfate is the white precipitate?

A

Barium sulfate

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10
Q

What tells you that a sulfate is present?

A

Barium sulfate.

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11
Q

What is the equation for the reaction producing barium sulfate?

A

Ba2+(aq) +SO4^2-(aq) = BaSO4(s)

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12
Q

What is used to test for halides?

A

Add nitric acid and then silver nitrate solution.

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13
Q

What will happen in the halide test if chloride, bromide or iodide is present?

A

A precipitate will form.

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14
Q

What colour precipitate is formed if chloride is present?

A

A yellow precipitate of silver chloride.

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15
Q

What colour precipitate is formed if bromide is present?

A

A cream precipitate of silver bromide.

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16
Q

What colour precipitate is formed of iodide is present?

A

A yellow precipitate of silver iodide.

17
Q

Why does fluoride give no precipitate when testing for halides?

A

Silver fluoride is soluble.

18
Q

How do you tell the ppts of halides apart?

A

Test their solubility in ammonia.

19
Q

Does AgCl dissolve in dilute NH3?

A

Yes

20
Q

Does AgCl dissolve in concentrated NH3?

A

Yes

21
Q

Does AgBr dissolve in dilute NH3?

A

No

22
Q

Does AgBr dissolve in concentrated NH3?

A

Yes

23
Q

Does AgI dissolve in dilute NH3?

A

No

24
Q

Does AgI dissolve in concentrated NH3?

A

No

25
Q

How do you test for ammonium compounds?

A

Use NaOH and damp litmus paper?

26
Q

Why does the litmus paper have to be damp when testing for ammonia?

A

This is so that the ammonia gas can dissolve and make the colour change.

27
Q

What colour litmus paper should be used to test for ammonium gas?

A

Red

28
Q

What colour will the ammonium gas turn the litmus paper?

A

It will turn it blue.

29
Q

Is ammonium gas acid or alkaline?

A

It is alkaline.

30
Q

What does the NaOH and litmus paper test tell you about a compound?

A

It tells you whether or not a substance contains ammonium ions.

31
Q

How do you carry out the test for ammonium compounds?

A

Add some sodium hydroxide to the test tube containing the sample and warm the mixture. If ammonia gas is given off, there are ammonium ions in the substance.

32
Q

What is the equation for testing for ammonium compounds?

A

NH4+(aq) + OH-(aq) = NH3(g) + H2O(l)

33
Q

What three compounds are insoluble?

A

Barium sulfate, barium carbonate and barium sulfite.

34
Q

What is important when testing for sulfates?

A

You must make sure that no carbonate ions or sulfite are present first.

35
Q

Why do you need to test for sulfate ions before halides?

A

This is because both sulfate and halide ions will produce ppts with silver nitrate.

36
Q

What will adding dilute acid do to the test solution?

A

It will remove anions.

37
Q

Which tests test for anions?

A

Carbonate, sulfate and halide tests.

38
Q

Which test tests for cations?

A

NaOH and litmus paper

39
Q

In what order should you test for anions?

A

Carbonates then sulfates then halides.