Page 39 - Curriculum Visions Dynamic Book

foam: a substance that is sufficiently gelatinous to be able to contain bubbles of gas. The gas bulks up the substance, making it behave as though it were semi-rigid.
gelatinous: a term meaning made with water. Because a gelatinous precipitate is mostly water, it is of a similar density to water and will float
or lie suspended in the liquid.
reagent: a starting material for a reaction.
 Carbon dioxide is used in fire extinguishers because it is not combustible. Surrounding a burning object with carbon dioxide therefore deprives the object of oxygen and the fire goes out. Carbon dioxide is also a non-polluting gas.
 Imagine that the fire extinguisher has been given a sharp tap to break the phial containing the aluminium sulphate solution, allowing it to mix with the sodium carbonate solution. The result
is an immediate reaction, producing a gelatinous foam of carbon dioxide gas that froths up and does not disperse. These agents together make for an efficient fire extinguishing combination.
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