Page 13 - Curriculum Visions Dynamic Book

EQUATION: Laboratory production of hydrogen
Hydrochloric acid + zinc ➪ zinc chloride + hydrogen 2HCl(aq) + Zn(s) ➪ ZnCl2(aq) + H2(g)
catalyst: a substance that speeds up a chemical reaction but itself remains unaltered
at the end of the reaction.
Chlorine
Hydrogen
Zinc
Also...
Hydrogen gas burns with a colourless flame and at a high temperature, and tends to melt the glass around the end of the tube as it burns. The orange-red colour of the flame you see is due to the presence of sodium in the glass; the sodium colours the flame.
Inflammable hydrogen
If hydrogen is not collected in the gas jar, it will seep out of the open tubing. In this picture the gas has been set alight, showing that hydrogen is inflammable.
The small size of
the flame shows that hydrogen is not produced at a particularly fast rate, but the flame is steady, showing how the copper sulphate catalyst plays a useful part in making the gas production constant. (Hydrogen actually burns with a colourless flame; the yellow colour is from some of the sodium
in the glass, released
as the flame heats the glassware.)
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