C3.4 Further analysis and quantitative chemistry Flashcards Preview

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Flashcards in C3.4 Further analysis and quantitative chemistry Deck (33)
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1
Q

Test for lithium?

A

a CRIMSON flame

2
Q

Test for sodium?

A

a YELLOW flame

3
Q

Test for potassium?

A

a LILAC flame

4
Q

Test for calcium?

A

a RED flame

or

forms a white precipitate in sodium hydroxide solution

5
Q

Test for barium?

A

a GREEN flame

6
Q

Test for aluminium?

A

Forms a white precipitate with sodium hydroxide solution and dissolves in excess sodium hydroxide solution

7
Q

What can flame tests be used to identify?

A

metal ions: Lithium, sodium, potassium, calcium, barium

compounds produce distinctive colours in flame tests

8
Q

Test for magnesium ions?

A

form white precipitates with sodium hydroxide solution

9
Q

Test for copper(II) ?

A

Forms blue precipitates with sodium hydroxide solution

10
Q

Test for iron(II)?

A

Forms a green precipitate with sodium hydroxide solution

11
Q

Test for iron(III) ?

A

Forms a brown precipitate with sodium hydroxide solution

12
Q

What colour precipitates do aluminium, calcium and magnesium form with sodium hydroxide solution?

A

White

13
Q

When carbonates react with dilute acids, what is formed?

A

carbon dioxide

14
Q

What is the test for carbon dioxide?

A

by bubbling it through limewater

produces white precipitates, causing lime water to turn cloudy if carbondioxide is present

15
Q

Acid + Carbonate———–

A

Salt + Water + Carbon Dioxide

16
Q

Halide ions in solution produce precipitates with…….

A

silver nitrate solution in the presence of dilute nitric acid

17
Q

Test for chloride ions?

A

Acidify with nitric acid

add silver nitrate solution

forms a white precipitate

18
Q

Test for bromide ions?

A

Acidify with nitric acid

add silver nitrate solution

forms a cream precipitate

19
Q

Test for iodide ions?

A

Acidify with nitric acid

add silver nitrate solution

forms a yellow precipitate

20
Q

Give examples of halide ions

A

chloride

bromide

iodide

21
Q

What chemicals are needed to test for halide ions?

A

silver nitrate solution and dilute nitric acid

22
Q

Test for sulfate ions?

A

a white precipitate is formed with dilute hydrochloric acid and barium chloride solution

23
Q

How can the volumes of acid and alkali solutions that react with each other be measured?

A

by titration using a suitable indicator

24
Q

What can titrations be used to do?

A

to find exactly how much acid is needed to neutralise quantity of alkali (or vice versa)

25
Q

What indicator is usually used in titrations?

A

phenolphthalein

26
Q

In titrations why do we use the indicator phenolphthalein instead of universal indicator?

A

As universal indicator changes colour gradually- we want a definite colour change

27
Q

Describe how to carry out titrations?

A

Put some alkali in the flask, along with some indicator- phenolphthalein

Put acid into the burette until it reaches 0 dm3

Add the acid a bit at a time to the alkali using the burette, giving the flask a regular swirl.

The indicator then changes colour when all the alkali has been neutralised.

Record the amount pf acid used to neutralise the alkali

repeat and calculate a mean

28
Q

In the equation

n= c x V

What do the letters stand for and what are the units?

A

n- number of moles

c- concentration in mol/dm3

V- Volume dm3

29
Q

In the equation

m = n X Mr

What do the letters stand for and what are the units?

A

m- mass (g)

n- number of moles

Mr- Relative formula mass

30
Q

Suggest why it is difficult to identify potassium ions when sodium ions are present in flame tests

A

as lilac colour of potassium is obscured by yellow colour of sodium

31
Q

Describe how a student could confirm a salt contains magnesium ions and not aluminium ions

A

add excess sodium hydroxide solution with salt

aluminium ions would dissolve

32
Q

Describe how a student could confirm a salt does not contain calcium ions

A

place sample in a flame (flame test)

flame does not go red

33
Q

Test for carbonate ion?

A

carbon dioxide is produced in the presence of a dilute acid