Text lesson

Unit 1 — Chemical Reactions and Their Environmental Impacts

Science — Third Preparatory

3.2 The tobacco plant and the products of tobacco combustion

The tobacco plant grows mainly in warm, tropical regions.
It has a thick upright stem, large green leaves and tubular flowers that may be white, pink or red.
The dried leaves are used to make cigarettes.
A simple experiment to collect cigarette smoke.

A transparent plastic bottle with a hole near the bottom (sealed by a stopper) is two-thirds filled with water.
A cigarette is fixed in a hole in the bottle cap, and a piece of white cotton is pressed into the mouth of the bottle.
The cigarette is lit and the stopper removed.
As water runs out, air is drawn through the cigarette, carrying its smoke into the bottle.
The white cotton slowly turns brown/dark as products of combustion are deposited among the fibres.
This shows that the smoke contains solid and sticky particles, not just gas.

Unit 1 — Chemical Reactions and Their Environmental Impacts · 20 / 30

3.2 The tobacco plant and the products of tobacco combustion