TESTS

Question 1

test for hydrogen gas:

Answer 1

place lit splint into a test tube and it should make a squeaky pop

Question 2

test for carbon dioxide:

Answer 2

bubble through limewater and it should turn from clear to cloudy

Question 3

test for oxygen:

Answer 3

glowing splint relights

Question 4

test for ammonia:

Answer 4

damp red litmus paper turns blue

Question 5

test for chlorine:

Answer 5

turns either damp litmus paper white

Question 6

how to carry out a flame test:

Answer 6

A flame test is used to show the presence of certain metal ions (cations) in a compound.

• A platinum or nichrome wire is dipped into concentrated hydrochloric acid to remove any impurities.
• The wire is dipped into the salt being tested so some salt sticks to the end.
• The wire and salt are held in a non-luminous (roaring) bunsen burner flame.
• The colour is observed.

Question 7

colour of lithium in a flame test:

Answer 7

red

Question 8

colour of sodium in a flame test:

Answer 8

yellow

Question 9

colour of calcium in a flame test:

Answer 9

orange-red

Question 10

colour of potassium in a flame test:

Answer 10

lilac

Question 11

colour of copper in a flame test:

Answer 11

blue- green

Question 12

test for NH4 + :

Answer 12

• add to sodium hydroxide and warm
• if ammonia is present ammonia gas will form
• this will turn damp red litmus paper blue

Question 13

test for CU2+ :

Answer 13

• add sodium hydroxide
• blue

Question 14

test for Fe2+ :

Answer 14

• add sodium hydroxide
• green

Question 15

test for Fe3+ :

Answer 15

• add sodium hydroxide
• brown

Question 16

test for CO3 2- :

Answer 16

• add HCl
• if carbonate atoms are present fizzing will occur
• test the gas for carbon dioxide using limewater

Question 17

test for Cl- :

Answer 17

• add nitric acid to remove impurities
• then add silver nitrate solution
• white

Question 18

test for Br- :

Answer 18

• add nitric acid to remove impurities
• then add silver nitrate solution
• cream

Question 19

test for I- :

Answer 19

• add nitric acid to remove impurities
• then add silver nitrate solution
• yellow

Question 20

test for SO4 2- :

Answer 20

• add HCl to remove any impurities
• then add barium chloride.
• if sulfate ons are present white precipitate barium sulfate will form

Question 21

chemical test for presence of water:

Answer 21

anhydrous copper sulfate turns from white to blue

Question 22

physical test for pure water:

Answer 22

boils at 100 degrees celsius
freezes at 0 degrees celsius