Flame tests to identify metal ions

Question 1

What does Lithium burn with?

Answer 1

red flame

Question 2

What does sodium burn with?

Answer 2

yellow flame

Question 3

What does potassium burn with?

Answer 3

lilac flame

Question 4

What does calcium burn with?

Answer 4

orange-red flame

Question 5

What flame do Copper ions give?

Answer 5

blue-green flame

Question 6

How do you do the flame test?

Answer 6

-you need a clean platinum wire loop by dipping it in some dilute HCL then holding it in a flame.
-once you hold the loop in the flame and it burns without any colour you can dip it into the sample you want to test
-then put it back in the clear part of the Bunsen flame (hottest part)

Question 7

When do some metals form a coloured precipitate?

Answer 7

With NaOH

Question 8

Are metal hydroxides insoluble or soluble?

Answer 8

Insoluble

Question 9

What is the test for finding which metal was in a compound?

Answer 9

• add a few drops of sodium hydroxide solution to a solution of your mystery compound in a test tube
• if you get a coloured insoluble hydroxide you can then tell which metal was in the compound

Question 10

What is the colour of precipitate with Copper (II) metal ion when added to NaOH?

Answer 10

blue

Question 11

What is the colour precipitate with Iron (II) metal ion?

Answer 11

Sludgy green

Question 12

What is the colour precipitate with Iron (III) metal ion when reacting with NaOH?

Answer 12

Reddish Brown

Question 13

How can you test for ammonia gas? What is the colour change?

Answer 13

-damp piece of red litmus paper
-if there is ammonia present, the paper will turn blue

Question 14

How can you test whether a substance contains ammonium ions?

Answer 14

-add some sodium hydroxide to a solution of your mystery substance in a test tube
- if there is ammonia given off this means there are ammonia ions in your mystery substance

Question 15

How can you test for carbonates?

Answer 15

• add dilute hydrochloric acid to your test sample
  -if carbonates are present then carbon dioxide will be released

Question 16

What do carbonates give off?

Answer 16

give off carbon dioxide with HCL

Question 17

What is the word equation for testing for carbonates?

Answer 17

carbonate + acid = carbon dioxide + water

Question 18

What precipitate do sulfate ions produce?

Answer 18

produce a white precipitate

Question 19

How do you test for a sulfate ion?

Answer 19

• add dilute HCL
• followed by barium chloride solution

Question 20

What does the white precipitate of barium sulfate mean?

Answer 20

The original compound was a sulfate

Question 21

Why is hydrochloric acid added?

Answer 21

• to get rid of any traces of carbonate or sulfate ions before you do the test
  -they would both produce a precipitate which would crowd the result

Question 22

How can you test for chloride, bromide, iodide ions?

Answer 22

• add dilute nitric acid followed by silver nitrate solution

Question 23

What does a chloride ion give? What is this word equation?

Answer 23

-white precipitate of silver chloride
- Ag (aq) + + Cl-(aq) = AgCl(s)

Question 24

What does a bromide ion give? What is this word equation?

Answer 24

-cream precipitate of silver bromide
- Ag+(aq) +Br(aq)- = AgBr(s)

Question 25

What does a iodide ion give? What is this word equation?

Answer 25

-yellow precipitate of silver iodide
- Ag+(aq) +I(aq)- = AgI(s)

Question 26

What is nitric acid used for?

Answer 26

• to get rid of carbonate or sulfite ions before the test