chemistry tests

Question 1

how to test for halide ions

Answer 1

1. Add dilute nitric acid to the sample
2. Add dilute silver nitrate solution
3. Halide ions produce a precipitate of the silver halide

each halide makes a different coloured precipitate

chloride ions - white precipitate of silver chloride
bromide ions - cream precipitate of silver bromide
iodide ions - yellow precipitate of silver iodide

Question 2

how to test for sulfate ions

Answer 2

1. Add dilute hydrochloric acid to our sample
2. Add barium chloride solution
3. If sulfate ions are present, we will see a white precipitate

Question 3

testing for gases (hydrogen)

Answer 3

to test for hydrogen, we remove the bong from a test tube that might contain hydrogen gas.

Hydrogen gas burns rapidly and produces a pop sounds (squeaky pop test)

Question 4

testing for gases (oxygen)

Answer 4

to test for oxygen, we use a glowing splint. If we place the glowing splint into a test tube of oxygen, the splint relights

Question 5

testing for gases (chlorine)

Answer 5

to test for CO2 we use limewater. Limewater is an aqueous solution of calcium hydroxide. We have a test tube containing a gas that might be CO2. We also have a test tube containing limewater.

1) First, we draw some of the gas into a plastic pipette
2) We then bubble the gas through the limewater

If we repeat this experiment several times, the limewater may turn cloud. If the limewater turns cloudy the that tel us that the gas is CO2