Identification of Species (PAG C5) Flashcards

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In PAG C5, what does "identification of species" mean in chemistry?

It means using chemical tests to find out which ions or gases are in an unknown sample.

Collect the gas in a test tube and hold a lit splint at the mouth. Hydrogen burns with a squeaky pop.

Put a glowing splint into the gas. Oxygen relights the glowing splint.

Bubble the gas through limewater. Carbon dioxide turns the limewater cloudy or milky.

Hold damp blue litmus paper in the gas, without breathing it in. Chlorine turns it red, then bleaches it white.

Dip the loop in dilute hydrochloric acid, then hold it in a hot Bunsen flame. Repeat until the flame shows no colour, so the loop is clean.

Lithium ions give a red flame, sodium ions a yellow flame, and potassium ions a lilac flame.

Calcium ions give an orange-red flame. Copper(II) ions give a blue-green flame.

Add a few drops of sodium hydroxide solution. Copper(II) makes a blue solid, iron(II) a green solid, and iron(III) a brown solid.

Add a dilute acid and look for fizzing as carbon dioxide is made. Bubble the gas through limewater; if it turns cloudy, carbonate ions were present.

Add a few drops of dilute hydrochloric acid, then barium chloride solution. A white solid (barium sulfate) shows sulfate ions are present.

Add dilute nitric acid, then silver nitrate solution. Chloride gives a white solid, bromide a cream solid, and iodide a yellow solid.