CHEMICAL TESTS
Flame tests are used to identify what metal is present. Although Magnesium and Iron are unable to be tested on because the flame will not give a specific colour change.
how to do each flame test
Sodium
Lithium
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the Lithium and the flame should be red.
Potassium
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the Potassium and the flame should be lilac.
Calcium
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the calcium and the flame should be brick red.
Copper
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the Copper and the flame should be blue green.
Barium
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the Barium and the flame should be apple green.
Strontium
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the Strontium and the flame should be red.
Gas tests are used to identify what gas is present around us but they all have different ways of testing which does not just include any ignited flames.
gas test
Hydrogen
Oxygen
Why do we need flame tests?
Mining
we use flame tests for mining to be able to see what ore was found.
geologist
to determine the artefact/ore found
fireworks
strontium is used in fireworks as their flame is very pretty
fireplace crystals
to clean the fireplace and a bonus point of having a nice flame whilst doing so.
Get the bunsen burner ready and have the hole for the bunsen burner be open, the flame should be blue. Dip the metal loop into diluted hydrochloric acid to clean the loop and put the loop into the flame; the flame should be orange. If the flame is not orange then dip the loop in hydrochloric acid again until the loop is clean. Once the loop is clean, dip the loop into the Sodium and the flame should be orange.
Oxygen can be tested by reigniting a splint. Sounds a little ridiculous but since Oxygen is a good at supporting combustion, a glowing splint will reignite. Like the squeaky pop test, the test tube containing Oxygen should be held bottoms up, this is because oxygen is less dense and will go up. Then take your glowing splint and insert it into the test tube, the splint should reignite.
Testing for Hydrogen involves the 'squeaky pop test'. In this experiment, you face the test tube, containing hydrogen bottoms up as Hydrogen gas is less dense and will go up. and get an ignited flint and insert it into the test tube. There should be a squeaky pop thus the name of the experiment, 'the squeaky pop test'.
Carbon dioxide
There are two ways of testing for Carbon Dioxide. One way is putting in an ignited splint where the fire will go out but other gases do this as well so it is not as accurate as the limewater experiment. In this experiment, you can either put a bung on top of the tube with Carbon Dioxide and insert the other end of the tube in the limewater and wait for the limewater to start becoming milky white. Another way to test for Carbon dioxide is just opening the tube of carbon dioxide and adding in a little bit of limewater and just shaking the mixture until the limewater turns cloudy.
Ammonia
Ammonia gas gives off a very chocking smell and can be tested by damping a red litmus paper and inserting it into the test tube containing the Ammonia gas. The damp litmus paper should turn blue.
Chlorine
Chlorine gives off a chocking smell and to test for it's presence, simply get a damp blue litmus paper and insert it into the test tube. The damp litmus paper should turn red and then be bleached white.
How do cations (negative ions) and Anions (positive ions) affect the flame tests
A metal salt consists of a component cation (the metal) and an anion. The anion can affect the result of the flame test. For example, a copper(II) compound with a non-halide produces a green flame, while a copper(II) halide yields a blue-green flame.
Why do we need gas tests?
Oil and gas industry
what gas have you found and will it be useful for combustion
Schools
teachers can show students how to do a gas test
school
Teachers show students how to do a flame test
gas leaks
in case there is an excess amount of poisonous gas in the composition of the air it can cause illnesses and deceases.
Testing for cations
When doing the flame test, firstly, grab a bunsen burner and have the hole open, the flame should be blue. Gather a metal loop and dip it into dilute hydrochloric acid and put it over the flame. The colour of the flame should be orange. Next, dip the metal loop in your cation, put it in the flames and observe the colour change of the flame.
This test uses sodium hydroxide or aqueous ammonia to test and identify metal ions by the precipitation formed. Sodium Hydroxide or Aqueous Ammonia is added to the solution being tested and the color of precipitation formed allows for identification of the compound.
Testing for anions
Barium ions react with sulfate ions, SO42- to form insoluble white barium sulfate: Ba2+(aq) + SO42-(aq) → BaSO4(s)
To test for sulfate ions in solution: add a few drops of dilute hydrochloric to the sample, add a few drops of dilute barium chloride solution. A white precipitate forms if sulfate ions are present.
This test has to be done in solution. If you start from a solid, it must first be dissolved in pure water. The solution is acidified by adding dilute nitric acid. (Remember: silver nitrate + dilute nitric acid.) The nitric acid reacts with, and removes, other ions that might also give a confusing precipitate with silver nitrate.
The hydrochloric acid is added first to remove any carbonate ions that might be present - they would also produce a white precipitate, giving a false positive result. Barium nitrate solution can be used instead of barium chloride solution. However, nitric acid is added first to acidify the test solution.