OCR B GCSE Chemistry Topic 1: Air and water

Flashcards about potable water and chlorine identification.

What is potable water?

Water that is suitable for drinking, having low levels of microbes and contaminating substances but is not the same as pure water.

What are the three main steps in making waste and ground water potable?

Sedimentation, filtration, and chlorination.

What happens during sedimentation?

Large insoluble particles sink to the bottom of the water.

What happens during filtration?

Water is filtered through beds of sand which removes small insoluble particles.

What happens during chlorination?

Chlorine gas is put through water to kill microbes.

What are the steps to making seawater potable using distillation?

Filter the seawater, boil it, and then cool and condense the water vapor.

Why is distillation expensive?

It requires large amounts of energy, making the process very expensive.

Why must water used in analysis be pure?

Any dissolved salts could react with the substances you are analysing, leaving you with a false result.

What happens when damp litmus paper is put into chlorine gas?

When damp litmus paper is put into chlorine gas, the litmus paper is bleached and turns white.