revision Flashcards
Define Endothermic
Chemical reactions that absorb heat energy from the surroundings .
Define exothermic
Chemical reactions that give out heat energy to the surroundings
Eg of endothermic
Ice Melting, photosynthesis, instant cold pack
eg of exothermic
campfire, lighting a match, rusting, water and acid reaction
Product
Chemical substances that result from a chemical reaction
Reactants
The original substances present in a chemical reaction
define acids
Chemicals that react with a base to produce a salt and water, edible acids taste sour
define bases
chemical substances that will react with an acid to produce a salt and water, edible bases taste bitter
eg of acids
Hydrochloric acid, Lemon, nitric acid, sulfuric acid
eg of bases
potassium hydroxide, sodium hydorxide, ammonia
Properties of acids
- acids have sour taste
-Acids have pH less than 7
Acids turn blue litmus red.
Properties of bases
-Bases change the colour of litmus from red to blue.
-They are bitter in taste.
Bases lose their basicity when mixed with acids
Indicator
A substance that changes color when it reacts with acids and bases. The color shows how acidic or basic a substance is
ph scale
The scale from 1-14 that measures how acidic or basic a substance is.
Which numbers represent acids
Numbers less than ph7 means that substances are acidic
