2(h) f + g required!

Question 1

State the test for Hydrogen(gas)

Answer 1

Lighted splint held to mouth of a tube with oxygen. Squeaky pop. 2H2 + O2&raquo_space; 2H2O

Question 2

State the test for Oxygen(gas)

Answer 2

Glowing splint relights.

Question 3

State the test for Carbon Dioxide(gas)(2)

Answer 3

Bubbled through limewater, limewater turns milky/cloudy.
Calcium Carbonate is formed, which is insoluble.

Question 4

State the test for Chlorine(gas)

Answer 4

Damp litmus paper or universal indicator paper put into test tube. Chlorine bleaches damp litmus paper or universal indicator. Red then white.

Question 5

State the test for Ammonia(gas)

Answer 5

NH3, turns universal indicator paper or red litmus paper blue.

Question 6

State the test for water?(2)

Answer 6

Anhydrous copper sulfate. Water turns it from white to blue. Works for anything contains H2O.
CuSO4(s) + 5H2O » CuSO4-5H2O(s)

Question 7

How is a flame test prepared?

Answer 7

Platinum or nichrome wire dipped into concentrated HCl then into salt that needs testing.

Question 8

Result of a Lithium flame test?

Answer 8

Red Flame shows lithium ions.

Question 9

Result of a sodium flame test?

Answer 9

Yellow Flame shows sodium ions.

Question 10

Result of a potassium flame test?

Answer 10

Lilac flame shows potassium ions.

Question 11

Result of a calcium flame test?

Answer 11

Orange-Red flame shows Calcium ions.

Question 12

Result of a copper(II) flame test?

Answer 12

Blue-Green flame shows copper(II) ions.

Question 13

How is a cation test with Sodium Hydroxide solution prepared?

Answer 13

Dissolve the salt in pure water and put some in a test tube. Add the same amount of volume of dilute sodium hydroxide solution.

Question 14

What is the result of a copper(II) with Sodium Hydroxide test?(2)

Answer 14

Blue precipitate is formed in presence of copper(II) ions.
Cu(2+)(aq) + 2OH(-)(aq) » Cu(OH)2

Question 15

What is the result of an iron(III) with Sodium Hydroxide test?(2)

Answer 15

Orange-brown precipitate is formed in presence of iron(III) ions.
Fe(3+)(aq) + 3OH(-)(aq) » Fe(OH)3

Question 16

What is the result of an iron(II) with Sodium Hydroxide test?(2)

Answer 16

Dirty green precipitate is formed in presence of iron(II) ions.
Fe(2+)(aq) + 2OH(-)(aq) » Fe(OH)2

Question 17

How can you test for ammonia in a solid or in solution?

Answer 17

Sodium hydroxide solution reacts with Ammonium to produce Ammonia gas which can be tested for.
NH4(+)(aq) + OH(-)(aq) » NH3(g) + H2O(l)

Question 18

What is the test for Carbonates and Sulphates?(4)

Answer 18

Add HCl to the sample with the carbonate. Gas is given off. Test the gas using limewater to see if it is CO2.
CO3(2-)(s) + 2H(+)(aq) » CO2(g) + H2O(l)
For sulphates, also add HCl to the sample with the sulphate. Then add Barium Chloride solution. White precipitate will form.
Ba(2+)(aq) + SO4(2-)(aq) » BaSO4

Question 19

How can we find out whether water is pure or not?

Answer 19

Measure freezing or boiling point. Pure water freezes at exactly 0 celsius and boils at exactly 100 celsius at 1 atmosphere pressure.

Question 20

How are Chlorides, Bromides and Iodides tested for?(3)

Answer 20

Add enough dilute nitric acid to make it acidic.
Add silver nitrate solution to chloride, bromide or iodide.
A white precipitate shows the presence of chloride ions, cream precipitate shows presence of bromide ions, yellow precipitate shows presence of iodide ions.