Page 35 - Curriculum Visions Dynamic Book

cation: a positively charged atom or group of atoms.
exothermic reaction:
a reaction that gives heat
to the surroundings. Adding sodium hydroxide to water is an example.
fat: semi-solid energy-rich compounds derived from plants or animals and which are made of carbon, hydrogen and oxygen. Scientists call these esters.
 Sodium hydroxide crystals. When added to water they create a hot, caustic solution.
 Oven-cleaning pads are made with caustic soda because a very strong reaction is needed. The reactive face of oven pads should not be handled because caustic soda will react with skin to form soap!
EQUATION: Caustic soda and water
Sodium hydroxide + water ➪ dilute sodium hydroxide NaOH(s) + H2O(l) ➪ NaOH(aq)
heat given off
Caustic soda and blocked drains
When caustic soda is added to water
and then put down a drain that has been blocked by fats and oils, the reaction of water and the sodium hydroxide produces a hot alkaline solution. Chemical reactions occur much faster when substances are hot rather than cold.
When hot sodium hydroxide reacts with animal fats, it breaks up the long chain-like molecules of the fat or oil, making short pieces that can easily be washed away.
EQUATION: Caustic soda and fat
Sodium hydroxide + fat ➪ soap + glycerol 3NaOH(aq) + (C17H35CO2)3C3H7(s) ➪ 3(C17H35CO2)Na(aq) + C3H7(OH)3(aq)
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