cations tests

Question 1

test for aqueos Cations

Answer 1

uses aqueous sodium hydroxide and ammonia

Question 2

process of testing for cations

Answer 2

aqueous sodium hydroxide and ammonia forming insoluble hydroxide salts which form as a precipitate

Question 3

what is a precipitate?

Question 4

ammonium ion

Answer 4

NH4 +

Question 5

sulphate ion

Answer 5

SO4^2-

Question 6

Carbonate ion

Answer 6

CO3^2-

Question 7

Nitrate ion

Answer 7

NO3-

Question 8

hydroxide ion

Answer 8

OH-

Question 9

testing NH4 +

Answer 9

Ammonia gas produced on heating; turns red litmus blue

Question 10

testing Ca^2+

Answer 10

forms White ppt

Question 11

testing Cu^2+

Answer 11

Light blue ppt

Question 12

testing Fe^2+

Answer 12

Green ppt

Question 13

testing Fe^3+

Answer 13

Red-brown ppt.

Question 14

testing Zn^2+

Answer 14

White ppt

Question 15

testing for some aqueous cations.

Answer 15

begin with solution that contains (Ca 2+ , Cu 2+ , Fe 2+ , Fe 3+ and Zn 2+) ions. Get five test tubes and add 2cm of each then add few drops of aqueous sodium hydroxide followed by an excess. Repeat using aqueous ammonia.

Question 16

testing for cations by flame test

Answer 16

take a wire with a loop and clean with hydrochloric acid.
Place the loop into some solid lithium chloride, to pick up a small amount.
Hold the loop in the Bunsen flame and observe colour change .
Clean wire and repeat with sodium chloride, potassium chloride and copper(II) chloride.

Question 17

LI +

Answer 17

red flame

Question 18

Na +

Answer 18

yellow flame

Question 19

K +

Answer 19

lilac flame

Question 20

Cu 2+

Answer 20

blue-green flame