Halide ions Flashcards Preview

Y12 AS Chemistry > Halide ions > Flashcards

Flashcards in Halide ions Deck (29)
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1
Q

How do group 7 elements form ions?

A

They gain one electron to form a full outer shell

2
Q

What is the reducing power of halides?

A

How easy it is for a halide ion to lose an electron depends on the attraction between the nucleus and the outer electrons

3
Q

What is the trend in reducing power of halides as you move down the group?

A

Increases

4
Q

What happens to the halide ions when they take part in a redox reaction?

A

It reduces something and is oxidised itself

5
Q

What do all halides react with to produce?

A

Concentrated sulphuric acid to give a hydrogen halide

6
Q

What is the general equation for a halide reacting with concentrated sulphuric acid?

A

NaX + H2SO4 _> NaHSO4 + HX

7
Q

What is the reaction of strong halides with concentrated sulfuric acid? What are the products?

A

2HX + H2SO4 + X2 + SO2 + 2H2O

Reduce the sulphuric acid to water and sulfur dioxide

8
Q

What are the 2 half equations for the reaction of strong halides with concentrated sulphuric acid?

A

2X- -> X2 + 2e-

H2SO4 + 2H+ + 2e- -> SO2 + 2H2O

9
Q

What can iodine reduce SO2 to and why?

A

H2S or S

It is such a strong reducing agent

10
Q

What is the equation for the reaction between NaF and H2SO4?

A

NaF + H2SO4 -> NaHSO4 + HF

11
Q

What is the equation for the reaction between NaCl and H2SO4?

A

NaCl + H2SO4 -> NaHSO4 + HCl

12
Q

What observation can be made from the reactions of NaF and NaCl reacting with concentrated sulphuric acid?

A

Misty fumes from either HF or HCl

13
Q

What are the equations for the two reactions of NaBr with H2SO4?

A

NaBr + H2SO4 -> NaHSO4 + HBr

2HBr + H2SO4 -> Br2 + SO2 + 2H2O

14
Q

Why are there two reactions for NaBr and H2SO4?

A

HBr is a stronger reducing agent than HCl and then reacts with the H2SO4 in a redox reaction

15
Q

What observations can be made from the first reaction of NaBr reacting with concentrated sulphuric acid?

A

Misty fumes of HBr

16
Q

What observations can be made from the second reaction of NaBr reacting with concentrated sulphuric acid?

A

Choking fumes of SO2

Orange fumes of Br2

17
Q

How many reactions are there when NaI reacts with concentrated sulfuric acid?

A

3

18
Q

What is the equation for the first reaction when NaI reacts with concentrated sulfuric acid?

A

NaI + H2SO4 -> NaHSO4 + HI

19
Q

What is the equation for the second reaction when NaI reacts with concentrated sulfuric acid?

A

2HI + H2SO4 -> I2 + SO2 + 2H2O

20
Q

What is the equation for the third reaction when NaI reacts with concentrated sulphuric acid?

A

6HI + SO2 -> H2S + 3I2 + 2H2O

21
Q

What observations can be made for the third reaction of NaI reacting with concentrated sulfuric acid?

A

Fumes of H2S

Solid iodine

22
Q

How do you test for halides?

A

1) add dilute nitric acid to remove ions which might interfere
2) add a few drops of silver nitrate solution

23
Q

What is the general equation for the reaction of halides with silver nitrate solution?

A

Ag+ + X- -> AgX

24
Q

What colour precipitate does chloride ions produce?

A

White

25
Q

What colour precipitate does bromide ions produce?

A

cream

26
Q

What colour precipitate does iodide ions produce?

A

Yellow

27
Q

What reaction occurs when dilute NH3 is added to chloride ions?

A

Dissolves

28
Q

What reaction occurs when concentrated NH3 is added to bromide ions?

A

Dissolves

29
Q

What reaction occurs when concentrated NH3 is added to iodide ions?

A

No reaction

Insoluble