Test for lithium?
a CRIMSON flame
Test for sodium?
a YELLOW flame
Test for potassium?
a LILAC flame
Test for calcium?
a RED flame
or
forms a white precipitate in sodium hydroxide solution
Test for barium?
a GREEN flame
Test for aluminium?
Forms a white precipitate with sodium hydroxide solution and dissolves in excess sodium hydroxide solution
What can flame tests be used to identify?
metal ions: Lithium, sodium, potassium, calcium, barium
compounds produce distinctive colours in flame tests
Test for magnesium ions?
form white precipitates with sodium hydroxide solution
Test for copper(II) ?
Forms blue precipitates with sodium hydroxide solution
Test for iron(II)?
Forms a green precipitate with sodium hydroxide solution
Test for iron(III) ?
Forms a brown precipitate with sodium hydroxide solution
What colour precipitates do aluminium, calcium and magnesium form with sodium hydroxide solution?
White
When carbonates react with dilute acids, what is formed?
carbon dioxide
What is the test for carbon dioxide?
by bubbling it through limewater
produces white precipitates, causing lime water to turn cloudy if carbondioxide is present
Acid + Carbonate———–
Salt + Water + Carbon Dioxide
Halide ions in solution produce precipitates with…….
silver nitrate solution in the presence of dilute nitric acid
Test for chloride ions?
Acidify with nitric acid
add silver nitrate solution
forms a white precipitate
Test for bromide ions?
Acidify with nitric acid
add silver nitrate solution
forms a cream precipitate
Test for iodide ions?
Acidify with nitric acid
add silver nitrate solution
forms a yellow precipitate
Give examples of halide ions
chloride
bromide
iodide
What chemicals are needed to test for halide ions?
silver nitrate solution and dilute nitric acid
Test for sulfate ions?
a white precipitate is formed with dilute hydrochloric acid and barium chloride solution
How can the volumes of acid and alkali solutions that react with each other be measured?
by titration using a suitable indicator
What can titrations be used to do?
to find exactly how much acid is needed to neutralise quantity of alkali (or vice versa)
What indicator is usually used in titrations?
phenolphthalein
In titrations why do we use the indicator phenolphthalein instead of universal indicator?
As universal indicator changes colour gradually- we want a definite colour change
Describe how to carry out titrations?
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
In the equation
n= c x V
What do the letters stand for and what are the units?
n- number of moles
c- concentration in mol/dm3
V- Volume dm3
In the equation
m = n X Mr
What do the letters stand for and what are the units?
m- mass (g)
n- number of moles
Mr- Relative formula mass
Suggest why it is difficult to identify potassium ions when sodium ions are present in flame tests
as lilac colour of potassium is obscured by yellow colour of sodium
Describe how a student could confirm a salt contains magnesium ions and not aluminium ions
add excess sodium hydroxide solution with salt
aluminium ions would dissolve
Describe how a student could confirm a salt does not contain calcium ions
place sample in a flame (flame test)
flame does not go red
Test for carbonate ion?
carbon dioxide is produced in the presence of a dilute acid