revision Flashcards
(18 cards)
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
Which numbers respresent bases
numbers more than ph7 means that substances are basic
which numbers represent neutral substances
if a substance has a ph of 7 it is neutral. neither acidic or basic
which end of the scale refers to strong acids and strong bases
Strong acids have a ph of 0 or 1
Strong bases have a ph of 13 or 14
