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Chemistry > P2 - 8.4 Test for Anions > Flashcards

P2 - 8.4 Test for Anions Flashcards

Chemical Analysis

1
Q

What is an anion

A

A negatively charged ion

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2
Q

What are the 3 tests we can do to test for anions

A
  • Carbonate ion
  • sulfate ion
  • halide ion
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3
Q

What are the products of a carbonate reacting with an acid

A

Salt + carbon dioxide + water

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4
Q

What is the equation for carbonates reacting with acid

A

Carbonate + acid -> salt + carbon dioxide + water

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5
Q

What is the test for carbon dioxide

A

Bubbling carbon dioxide gas through lime water
If it turns cloudy then CO2 is present

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6
Q

What is the test for carbonates

A

Add dilute HCl (hydrochloric acid) to our test sample and take any gas produced ( if carbonate it should be CO2) and run it through limewater, if it turns cloudy it is a carbonate

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7
Q

What would be a positive test result for testing for carbonates

A

If the limewater turns cloudy it means carbon dioxide would have been produced which is a product of a carbonate and dilute hydrochloric acid (HCl) mixing together

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8
Q

What would be a positive test result for testing for carbon dioxide

A

Limewater turning cloudy

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9
Q

What would be a negative test result for testing for carbon dioxide

A

If the limewater did not turn cloudy it would mean there was no carbon dioxide

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10
Q

What would be a negative test result for testing for carbonates

A

If the limewater did not turn cloudy then that would mean no CO2 was produced, meaning there was no carbonate in sample

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11
Q

What is a positive test result

A

When what your testing for is present

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12
Q

What is a negative test result

A

When the thing you are testing for is not present

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13
Q

What ions do we add to test for sulfates

A

Barium ions

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14
Q

What is the symbol equation for testing for sulfates

A

Ba^2+ (aq) + SO4^2- (aq) -> BaSO4 (s)

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15
Q

What is the word equation for testing for sulfates

A

Barium ions + sulfate ions -> barium sulfate

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16
Q

What colour precipitate is barium sulfate

17
Q

What is the positive result when testing for sulfate

A

If we see a white precipitate forming then there is a sulfate

18
Q

What is the negative result of testing for sulfate

A

If no white precipitate forms then there is no sulfate present

19
Q

What is the first step to test for sulfates

A

Add some dilute hydrochloric acid (HCl) into a test tube with barium ions to remove any carbonates and sulfate ions that could give us a false result as they also become a white precipitate when reacted with barium chloride solution

20
Q

What is the second step to testing for sulfates

(After HCl has been added)

A

Add barium chloride solution (BaCl2) which contains barium ions that will cause a white precipitate to form showing a positive result

21
Q

Describe the test for testing for sulfates

A

1) Add some dilute hydrochloric acid (HCl) into a test tube with barium ions to remove any carbonates and sulfate ions that could give us a false result as they also become a white precipitate when reacted with barium chloride solution

2) Add barium chloride solution (BaCl2) which contains barium ions that will cause a white precipitate to form showing a positive result

22
Q

What are the 3 main halide ions we test for

A
  • chloride
  • bromine
  • iodide
23
Q

What is the first step when testing for a halide ion

A

Add dilute nitric acid to get rid of all carbonate and sulfate impurities

24
Q

What is the second step when testing for halide ions

A

Add silver nitrate (AgNO3) because the silver reacts with the halide to form a precipitate

Yellow = iodide ion
Cream = bromide ion
White = chloride ion

25
Describe the test for testing for halide ions
1) Add dilute nitric acid to get rid of all carbonate and sulfate impurities 2) Add silver nitrate (AgNO3) because the silver reacts with the halide to form a precipitate Yellow = iodide ion Cream = bromide ion White = chloride ion
26
What would be a positive result for testing for halide ions
Yellow = iodide ion Cream = bromide ion White = chloride ion
27
If a halide ion test formed a white precipitate what halide ion is present
Chloride ion
28
If a halide ion test formed a cream precipitate what halide ion is present
Bromide ion
29
If a halide ion test formed a yellow precipitate what halide ion is present
Iodide ion
30
What is the word equation for testing for halide ions
Silver ions + halide ions -> precipitate
31
What is the symbol equation for a halide ion test where chloride ions are present
Ag+ (aq) + Cl- (aq) -> AgCl (s)
32
What is the symbol equation for a halide ion test where bromide ions are present
Ag+ (aq) + Br- (aq) -> AgBr (s)
33
What is the symbol equation for a halide ion test where iodide ions are present
Ag+ (aq) + I- (aq) -> AgI (s)
34
A chemical reaction is taking place in a test tube. What methods could be used to collect the gas? (Select all that apply) 1) Place an upside down measuring cylinder over the test tube to trap the gas 2) Place the reaction beaker on a set of scales 3) Attach the top of the test tube to a gas syringe
1) Place an upside down measuring cylinder over the test tube to trap the gas 3) Attach the top of the test tube to a gas syringe
35
When testing for halide ions, is nitric acid or hydrochloric acid used?
Nitric acid
36
An unknown solution is mixed with hydrochloric acid and then barium chloride. A white precipitate forms. Which anion did the solution contain?
Sulfate ions
37
An unknown solution is mixed with hydrochloric acid and bubbles of gas are given off. The gas is bubbled through limewater and the limewater turns cloudy.
Carbonate ions
38
An unknown solution is mixed with nitric acid and then silver nitrate. A white precipitate forms. Which anion did the solution contain?
Chloride ions

Chemistry (91 decks)

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