Qualitative anylasis Flashcards
What do we do at the beginning when we are testing for ammonium ions?
About 10 drops of a solution containing ammonium ions should be added to a clean test tube
What do we add to our ammonium ions solution when testing for ammonium ions?
About 10 drops of sodium hydroxide using a pipette
What is the equation of ammonium ions solution with sodium hydroxide?
NH4X + NaOH = NH3 + H2O + NaX
What should be done to the test tube when testing for ammonium ions?
Should be swirled carefully to ensure that it is mixed well
What should be done to our test tube of solution when testing for ammonium ions after it has been swirled?
Placed in a beaker of water which should which should be placed above a bunsen burner so it becomes a water bath
What happens as the solution is gently heated when testing for ammonium ions?
Fumes will be produced
How do we confirm that there are ammonium ions in the heated test tube solution?
- Use tongs to hold a damp piece of red litmus paper near the mouth of the test tubes
- Will become blue in presence of ammonia gas
How do we start the test for carbonate ions?
A small amount of dilute HCl is added to a test tube using a pipette
An equal amount of sodium carbonate solution added using a clean pipette
What is the equation between HCl and sodium carbonate solution?
2HCl + Na2CO3 = 2NaCl + CO2 + H2O
What should happen as soon as the sodium carbonate solution is added to the dilute HCl?
A bung with a delivery tube should be attached to the test tube
What is the purpose of the delivery tube in testing for carbonate ions test?
It should transfer the gas formed into a different test tube which contains a small amount of limewater
What is limewater?
Calcium hydroxide solution
What will happen when the gas produced from sodium hydrogen carbonate and HCl acid reacts with limewater?
Carbonate ions will react with hydrogen ions from the acid to produce CO2 gas
What will CO2 gas turn the limewater?
Will turn it milky
what is the reaction of HCl with sodium hydrogen carbonate?
HCl + NaHCO3 = NaCl + CO2 + H2O
How do we test for sulphate ions?
Acidify the sample with dilute HCl and then add a few drops of aqueous barium chloride
What will happen if a sulphate ion is present in the test for sulphate ions?
A white precipitate of barium sulphate is formed
Ba2+ + SO42- = BaSO4
