Identifying the Products of Chemical Reactions (OCR GCSE Combined Science A (Gateway): Chemistry): Flashcards

Carbon dioxide is tested by bubbling the gas through limewater (calcium hydroxide solution). A positive result is that the limewater turns milky or cloudy.

The squeaky pop test is used to identify hydrogen gas. A burning splint held at the mouth of a test tube containing hydrogen produces a loud squeaky popping sound as the hydrogen combusts rapidly with oxygen.

True.

A glowing splint placed inside a test tube of oxygen will relight. This is because oxygen supports combustion, providing enough oxygen to reignite the glowing splint.

Chlorine gas bleaches damp blue litmus paper turning it white.

Chlorine should always be handled in a fume cupboard because it is toxic. Inhaling chlorine gas is hazardous to health.

False.

Extinguishing a burning splint is not a reliable test for carbon dioxide because other gases (such as nitrogen) can also extinguish a flame. The definitive test for CO₂ is bubbling it through limewater, which turns milky (cloudy).

When the burning splint is held at the tube's opening, hydrogen undergoes rapid combustion with oxygen in the air to produce water. The speed of this reaction creates the characteristic popping sound.

To test for oxygen, place a glowing splint inside the test tube. A positive result is that the splint relights.

Chlorine reacts with water in the damp litmus paper to produce an acid, which briefly turns the paper red. The chlorine then bleaches the paper white, destroying the dye in the litmus.