Tests for Cations

Question 1

how do you carry out a flame test?

Answer 1

clean a wire loop by dipping it in dilute HCl then holding it in a flame. once you 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 blue part of the bunsen flame.

Question 2

what colour is formed when LITHIUM burns?

Answer 2

Li+ burns with a red flame

Question 3

what colour is formed when SODIUM burns?

Answer 3

Na+ burns with a yellow flame

Question 4

what colour is formed when POTASSIUM burns?

Answer 4

K+ burns with a lilac flame

Question 5

what colour is formed when CALCIUM burns?

Answer 5

Ca2+ burns with an orange/ red flame

Question 6

what colour is formed when COPPER burns?

Answer 6

Cu2+ ions give a blue-green flame

Question 7

how to test for cations with sodium hydroxide solution?

Answer 7

1. test tube containing test solution
2. add sodium hydroxide solution drop by drop
3. swirl after each drop. look carefully for any precipitate
4. if there is no precipitate, warm the mixture gently with a bunsen burner and test any gas with moist litmus paper.

Question 8

what happens when you test Ammonium using sodium hydroxide solution

Answer 8

NH4+ = no precipitate, but when heated gas turned moist red litmus paper blue

Question 9

what happens when you test Iron (II) using sodium hydroxide solution

Answer 9

Fe2+ = dark green precipitate

Question 10

what happens when you test copper (II) using sodium hydroxide solution

Answer 10

Cu2+ = dark blue precipitate

Question 11

what happens when you test iron (III) using sodium hydroxide solution

Answer 11

Fe3+ = orange ppt