Chemical Gas tests

Salt solubility test

What reagents are needed to carry out the test?

What is the test is used to identify?

What colour change might be observed for a positive test (include before AND after colour)?

Hydrogen gas test: Hydrogen gas, splint, match, test tub, bung

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Oxygen gas test: Is used to test for the presence of oxygen

Ammonia gas test: Is used to test for the presence of ammonia

Carbon dioxide gas test: Is used to test for the presence of carbon dioxide

Chlorine gas test: Is used to test for the presence of chlorine

Hydrogen gas test: Is used to test for the presence of hydrogen

Oxygen gas test: No colour change

Chlorine gas test: Blue litmus paper turns red then bleaches

Hydrogen gas test: No colour change

Ammonia gas test: Red litmus paper turns blue

Carbon dioxide gas test: Limewater turns from transparent to cloudy/milky opaque

Oxygen gas test: Oxygen gas, splint, match, test tube, bung

Chlorine gas test: Chlorine gas, test tube, bung, damp UI or blue litmus paper

Instructions:
1) Lower a lighted splint into a test tube with hydrogen gas.
2) If it does have hydrogen, a 'squeaky pop' will be heard

Ammonia gas test: Ammonia gas, test tube, bung, damp red litmus paper

Ammonia gas test: Ammonia is used in agriculture as fertilizer. It is also used as a refrigerant gas, to purify water, and in the manufacturing process of plastic. Ammonia is corrosive to tissue, thus it is a hazard if breathed in. Ammonia gas tests can be used to test the alkalinity of fertilizer and as a precaution if there is a gas leak.

Chlorine gas test: Chlorine is used to disinfect pools and is part of the sanitation process for sewage systems. Back in war times, chlorine was also used in warfare because it caused acid burns in lunges when inhaled. Chlorine gas tests can be used as a precaution and to make sure nothing is leaked.

What is the relevance of each test? What might it be used for in real life?

Hydrogen gas test: Back then, hydrogen gas was used in airships and airborne vehicles because it was less dense than air, making it float. Helium was not used because, at the time, it was more expensive. Hydrogen is now used to power some cars, to generate electricity and more.

Oxygen gas test: Oxygen is necessary for life. It is used in aerobic respiration which releases energy for us to carry out our daily life processes eg. moving, breathing, etc. It is also used in the welding and cutting of metals

Carbon dioxide gas test: Carbon dioxide gas, test tubes, bung, glass delivery tube, limewater.

Chemical flame cation tests

What reagents are needed to carry out the test?:

Carbon dioxide gas test: Carbon dioxide is known to be used in fire extinguishers because it does not promote/encourage combustion. It is also used in photosynthesis in plants, which helps them make food for themselves.

What colour change might be observed for a positive test (include before AND after colour)?:

What is the test is used to identify?:

What is the relevance of each test? What might it be used for in real life?:

Potassium flame test: To test for potassium/colour of potassium flame

Calcium flame test: To test for calcium/colour of calcium flame

Sodium flame test: To test for sodium/colour of sodium flame

Copper flame test: To test for copper/colour of copper flame

Lithium flame test: To test for lithium/colour of lithium flame

Potassium flame test: We need potassium to help maintain normal levels of fluid in our cells. It also helps muscles to contract and supports normal blood pressure.

Calcium flame test: Calcium keeps bones and teeth strong, plays an important role in blood clotting, helps muscles contract, and regulates normal heart rhythms and nerve functions.

Sodium flame test: Sodium is used as a heat exchanger in some nuclear reactors, or as a reagent in the chemical industry. It is also part of sodium chloride, which is table salt.

Copper flame test: Copper is used in electrical generators and wiring, motors, and in electronic goods, eg. TV's and radios. Copper also conducts heat well, so it is used in motor vehicle radiators, air-conditioners and home heating systems.

Lithium flame test: Lithium can be used as a mood stabilising medicine, which can treat bipolar disorder or mania/hypomania

Potassium flame test: Potassium (K+), nichrome wire loop, dilute hydrochloric acid, bunsen burner

Calcium flame test: Calcium (Ca2+), nichrome wire loop, dilute hydrochloric acid, bunsen burner

Sodium flame test: Sodium (Na+), nichrome wire loop, dilute hydrochloric acid, bunsen burner

Copper flame test: Copper (Cu2+), nichrome wire loop, dilute hydrochloric acid, bunsen burner

Lithium flame test: Lithium (Li+), nichrome wire loop, dilute hydrochloric acid, bunsen burner

Potassium flame test: Flame colour: Lilac

Calcium flame test: Flame colour: Orange-red

Sodium flame test: Flame colour: Yellow

Copper flame test: Flame colour: Blue-green

Lithium flame test: Flame colour: Red

Salt solubility test

Key meanings:

Soluble: When something can dissolve in a solvent

Solvent: Something that can dissolve a solute

Solute: Something that can dissolve in a solvent

Solution: When a solute and solvent are mixed together

Soluble salts:

Precipitate: An insoluble solid (usually a salt) in a solution produced when two solutions are mixed.

Precipitation: The reaction that forms a precipitate

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What is the test used to identify?

Common ammonium salts

Common halides (Except silver & lead)

Common potassium salts

Common sulfates (Except barium & calcium)

Common sodium salts

All nitrate salts

Insoluble salts:

Silver/lead chloride/bromide/iodide

Barium/calcium/lead sulfate

Common hydroxides (Except sodium, potassium and ammonium)

magnesium/calcium/strontium/barium/aluminium/iron/copper/zinc/lead carbonate

Common carbonates (Except sodium, potassium & ammonium)

magnesium/calcium/strontium/barium/aluminium/iron/copper/zinc/lead hydroxide,

Ammonium solubility test: Used to identify ammonium ions

Halide solubility test: Used to identify halide ions

Potassium solubility test: Used to identify potassium ions

Sulfate solubility test: Used to identify sulfate ions

Sodium solubility test: Used to identify sodium ions

Nitrate solubility test: Used to identify nitrate ions

What reagents are needed to carry out the test?

Potassium solubility test: Two test tubes, potassium solution, second solution (should create a precipitate), pipette

Ammonium solubility test: Two test tubes, ammonium solution, second solution (should create a precipitate), pipette

Sodium solubility test: Two test tubes, sodium solution, second solution (should create a precipitate), pipette

Halide solubility test: Two test tubes, halide solution, second solution (should create a precipitate), pipette

Nitrate solubility test: Two test tubes, nitrate solution, second solution (should create a precipitate), pipette

Sulfate solubility test: Two test tubes, sulfate solution, second solution (should create a precipitate), pipette

Instructions:
1) Add the two solutions in separate test tubes.
2) Add one of the solutions to the other drop by drop using a pipette.
3) Watch the reaction and what precipitate is formed

Chemical Cation tests

What reagents are needed to carry out the test?:

What is the test used to identify?:

What is the relevance of each test? What might it be used for in real life?:

What colour change might be observed for a positive test (include before AND after colour)?:

Copper sulfate cation test: Two test tubes, copper sulfate (as liquid), sodium hyrdroxide, pipette

Aluminum chloride cation test: Two test tubes, aluminum chloride (as liquid), sodium hyrdroxide, pipette

Iron (lll) cation test: Two test tubes, iron (lll) (as liquid), sodium hyrdroxide, pipette

Calcium chloride cation test: Two test tubes, calcium chloride (as liquid), sodium hyrdroxide, pipette

Iron (ll) cation test: Two test tubes, iron (ll) (as liquid), sodium hyrdroxide, pipette

Instructions:
1) Add sodium hyrdroxide with a pipette to the elements below (in liquid form)
2) Observe any change in colour/reaction

Copper sulfate:

Aluminum chloride:

Iron (lll):

Calcium chloride:

Iron (ll):

Original colour = Clear yellow

Colour change = Orange red (Precipitate: Iron hydroxide or Fe(OH)3)

Official colour change = Brown

Original colour = Orange brown

Colour change = Black green (Precipitate: Iron hydroxide or Fe(OH)2)

Official changed colour = Green

Original colour = Clear turquoise

Colour change = Blue (Precipitate: Copper hydroxide or Cu(OH)2)

Official changed colour = Blue

Original colour = Clear/transparent

Colour change = Milky white/cloudy (Precipitate: Aluminum hydroxide or Al(OH)3)

Official changed colour = Milky white

Original colour = Clear/transparent

Colour change = Milky white/cloudy (Precipitate: Calcium hydroxide or Ca(OH)2)

Official changed colour = Milky white

Copper sulfate: To test for copper sulfate cations

Aluminum chloride: To test for aluminum chloride cations

Iron (lll): To test for iron (lll) cations

Calcium chloride: To test for calcium chloride cations

Iron (ll): To test for iron (ll) cations

To differentiate between iron (ll) and iron (lll)

To determine what cation could be in a solution

To test for cations (postitive ions)

What is the relevance of each test? What might it be used for in real life?:

How much a solvent can dissolve before it stops

To determine what salts could be in a solution

To determine the solubility of a salt

Chemical Anions tests

What reagents are needed to carry out the test?:

Sulfate test:

What is the test used to identify?:

Bromide: To test for halide (bromide) anions

Iodide: To test for halide (iodide) anions

Chloride: To test for halide (chloride) anions

Carbonate: To test for metal carbonate anions

Sodium sulfate: To test for sulfate anions

What is the relevance of each test? What might it be used for in real life?:

To differentiate between the 3 halides (chloride, bromide and iodide)

To determine what anion could be in a solution

To test for anions (negative ions)

What colour change might be observed for a positive test (include before AND after colour)?:

Any carbonate (CO3 2-):

Original colour (limewater) = Clear

Colour change (limewater) = Foggy (From CO2 gas)

Chloride (Cl-):

Original colour = Clear/transparent

Colour change = White (Precipitate: Silver chloride or AgCl)

Sodium sulfate (Na2SO4):

Original colour = Clear/transparent

Colour change = White (Precipitate: Barium sulfate or BaSO4)

Non metal-cation test:

Ammonium cation: Instructions are the same: Add sodium hydroxide to the solution drop by drop with a pipette. But once you have done so, place the test tube in a warm water bath. Once it is placed, hang a damp red strip of litmus paper into the tube and observe what happens. If it is a positive test, heating the tube would produce ammonia gas and make the litmus paper blue.

Original colour of litmus paper: Red

Colour change of litmus paper: Blue (From ammonia gas)

Halides test:

Carbonate test:

Instructions for sodium sulfate test:

2) Add dilute hydrochloric acid with a pipette to the sulfate solution

3) Add barium chloride drop by drop with a pipette

4) Note your observations

Instructions for chloride, bromide & iodide test:

1) Have three separate tubes for chloride, bromide and iodide solutions

2) Add dilute nitric acid with a pipette to the sulfate solution

3) Add silver nitrate drop by drop with a pipette

4) Note your observations

Instructions for carbonate test:

1) Add any carbonate solution into a test tube

2) Add a few drops of hydrochloric acid with a pipette to the solution

3) Use a delivery tube to pass the gas through 1 cm^3 of limewater

4) Note your observations

1) Add sodium sulfate solution into a test tube

Bromide (Br-):

Iodide (I-):

Original colour = Clear/transparent

Colour change = Cream/beige (Precipitate: Silver bromide or AgBr)

Original colour = Clear/transparent

Colour change = Yellow (Precipitate: Silver iodide or AgI)

Instructions for flame tests:
1) Dip the nichrome wire loop into dilute hydrochloric acid and place in blue (non-luminous) bunsen flame to clean it
2) Dip it into the HCl acid again and then the compound you are going to test.
3) Place the wire into the blue Bunsen flame.
4) Note the colour of the flame

Instructions:
1) Add carbon dioxide to limewater
2) If there is carbon dioxide, the limewater will turn milky white

Instructions:
1) Put a recently extinguished splint into a test tube with oxygen
2) If there is oxygen, the splint will relight

Instructions:
1) Insert a damp blue litmus paper into the gas.
2) If there is chlorine, the litmus will turn red then bleach (turn white

Instructions:
1) Insert a damp red litmus paper into the gas.
2) If there is ammonia, the litmus will turn blue

Testing for water

Physical test:

Chemical test:

What reagents are needed to carry out the tests?:

Boiling & freezing tests:

White anhydrous copper sulfate test:

Instructions for freezing point test:

1) Cool water to 0 degrees Celsius

2) If the water freezes solid, then it pure water

Instructions for boiling point test:

1) Add water to a beaker

2) Heat up the water to 100 degrees Celsius

3) If the water starts boiling/bubbling then it is pure water

Instructions:

1) Add hydrated, blue copper sulfate to a test tube

2) Hold the test tube over a bunsen burner with a blue flame

3) As soon as the majority of the copper sulfate has turned white into white anhydrous copper sulfate, let it cool for around 30 seconds

4) Once it is cooled, drop water onto the copper sulfate with a pipette

5) If the copper sulfate turns back to blue, water (H2O) is present

Freezing test: Container (something that won't break when freezing), water, something to freeze the ice (fridge, cooler, etc) thermometer

White anhydrous copper sulfate test: Hydrated, blue copper sulfate, test tube, bunsen burner, pipette, water

Boiling test: Beaker, water, bunsen burner, thermometer

What colour change might be observed for a positive test (include before AND after colour)?:

White anhydrous copper sulfate test:

Original Colour: White

Colour change (when rehydrated): Blue

What is the test used to identify?:

Boiling test: To determine how pure is the water/if it is water

Freezing test: To determine how pure the water is/if it is water

White anhydrous copper sulfate: To determine if water is present

What is the relevance of each test? What might it be used for in real life?:

Freezing test: To test for the purity of the water, (in daily life) to freeze for cooling purposes

White anhydrous copper sulfate test: To test if water is present in a solution

Boiling test: To test for the purity of the water, (in daily life) to kill bacteria in water to make it drinkable

Why the specific equipment is needed:

Nichrome wire: Nichrome is usually used when heating up elements because it has a higher resistivity (the resistance of a wire of a substance) than copper (which is another common element used in wires), making the nichrome easier to control. It is also used because it does not produce a colour when placed in the flame and therefore won't interfere with the colour of the burning compound and compromise the results

HCl acid (Hydrochloric acid): The nichrome wire needs to be dipped into the hydrochloric acid to clean off any residue on the wire, because any residue will form chlorides, which are volatile (can easily vaporize into gas) when in fire

Non-luminous flame: The flame from the bunsen burner must be blue/non-luminous. This because non-luminous flames are the hottest and represent complete combustion. Luminous flames represent incomplete combustion, and create soot on the surface of whatever it is burning (e.g. test tube). The soot will compromise the results because it would be harder for us to distinguish the colour of the burning compound from it covering the tube, which is why a non-luminous flame must be used. In addition, the bright, orange-yellow colour of the luminous flame makes it hard to tell the results too, whilst the colourless non-luminous flame can be seen through easily