Test for ions

Question 1

what is an anion

Answer 1

a negatively charged ion

Question 2

what is a cation

Answer 2

a positively charged ion

Question 3

hydrogen test

Answer 3

(Gas) a lighted a splint is inserted into a test tube and makes a squeaky pop when the it reacts with the oxygen in the air.

Question 4

oxygen test

Answer 4

(Gas) oxygen relights a glowing splint

Question 5

carbon dioxide test

Answer 5

(Gas) bubble the CO2 through a test tube of limewater and it will turns cloudy

Question 6

ammonia test

Answer 6

(Gas) turns damp red litmus paper blue (it also has a very strong smell)

Question 7

chlorine test

Answer 7

(Gas) chlorine bleaches damp blue litmus paper turning it white

Question 8

how do you carry out a flame test

Answer 8

To do the test you need to clean a platinum wire loop by dipping it in some dilute hCL and then holding it in a flame.
If it burns without any colour, you can start testing the samples. You dip it in the sample and put it in the clear blue part of the bunsen flame.

Question 9

(cation) lithium test

Answer 9

Li⁺ red flame

Question 10

(cation) sodium test

Answer 10

Na⁺ yellow flame

Question 10

(cation) potassium test

Answer 10

K⁺ lilac flame

Question 11

(cation) calcium test

Answer 11

Ca²⁺ orange red flame

Question 12

(cation) copper test

Answer 12

Cu²⁺ blue-green flame

Question 13

Test for ammonium ions?

Answer 13

(NH₄⁺) add some sodium hydroxide to a solution of your mystery substance in a test tube. if there’s ammonia given off this means there are ammonium ions in your mystery substance.
damp red litmus paper turned blue

Question 14

copper reacts with sodium hydroxide (NaOH)

Answer 14

(Cu²⁺)
Blue precipitate
Cu²⁺(aq) + 2OH⁻(aq) → Cu(OH)₂(s)

Question 15

iron with sodium hydroxide (NaOH)

Answer 15

(Fe²⁺)
sludgy green precipitate
Fe²⁺(aq) + 2OH⁻(aq) → Fe(OH)₂(s)

Question 16

sodium hydroxide (NaOH) iron 3

Answer 16

(Fe³⁺)
Reddish Brown precipitate
Fe³⁺(aq) + 3OH⁻(aq) → Fe(OH)₃(s)

Question 17

(Anion) Test for chloride ions?

Answer 17

(Cl⁻) add dilute nitric acid (HNO₃) followed by silver nitrate (AgNO₃)
A chloride ion gives a white precipitate of silver chloride

Question 18

(Anion) Test for bromide ions?

Answer 18

(Br⁻) add dilute nitric acid (HNO₃) followed by silver nitrate (AgNO₃)
A bromide ion gives a cream precipitate of silver bromide

Question 19

(Anion) Test for iodide ions?

Answer 19

(I⁻) add dilute nitric acid (HNO₃)followed by silver nitrate (AgNO₃)
iodide ion gives a yellow precipitate of silver iodide

Question 20

(Anion) Test for sulfate ions?

Answer 20

(SO₄²⁻)
Add dilute HCL, followed by barium chloride solution (BaCl₂)
if it produces a white precipitate the original compound was a sulphate
the hcl is to get rid of any carbonate or sulfite before you do the test
Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)
Barium ions + sulfate ions → barium sulfate

Question 21

(Anion) test for carbonate ions?

Answer 21

(CO₃²⁻)
add dill hydrochloric acid to your test sample
if co2 is present it will be released
do the limewater test
CO₃²⁻(aq) + 2H⁺(aq) → H₂O(l) + CO₂(g)
Carbonate + acid → water + carbon dioxide

Question 22

Test for pure water?

Answer 22

Boils at 100°C; freezes at 0°C.

Question 23

Test for water using anhydrous copper(II) sulfate ?

Answer 23

(CuSO₄)
When copper(I) sulfate is bound to water it forms lovely blue crystals.
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2) If you heat the blue hydrated copperI) sulfate crystals it drives the water off.
3) This leaves a white anhydrous copperI) sulfate powder, which doesn’t have any water bound to it.

If you then add a couple of drops of water to the white powder you get the blue crystals back again.

So, if you want to test for water, all you need to do is add anhydrous copper (I) sulfate and see if the white powder turns blue.
This test will tell you if water is present in a solution but it won’t tell you if the water is pure.