4.7.3 Acids and Alkalis Flashcards
What is made when a metal reacts with an acid?
A salt and hydrogen
How do we test for hydrogen gas?
Put a lit splint into it - it makes a squeaky pop
What is made when an acid reacts with an alkali or base?
A salt and water
What gas is produced when a carbonate reacts with an acid?
Carbon dioxide
How do we test for carbon dioxide gas?
Use limewater - it turns cloudy when carbon dioxide is present
What is a neutralisation reaction?
An acid and alkali react together to form neutral substances
What is the difference between an alkali and a base?
An alkali will dissolve in water (is soluble) but a base is insoluble.
What is the name of the salt made when magnesium and hydrochloric acid react together?
Magnesium Chloride
What is the name of the salt made when magnesium reacts with nitric acid?
Magnesium nitrate
What is the name of the salt made when magnesium reacts with sulphuric acid?
Magnesium Sulphate
How do you collect an INSOLUBLE SALT?
FILTER it from the mixture.
How do you collect a SOLUBLE salt?
EVAPORATE off the water to collect the CRYSTALS
What is an exothermic reaction?
A reaction that releases heat energy- and heats up the reaction mixture.
What is an endothermic reaction?
A reaction that absorbs heat energy - and cools down the reaction mixture.
What ion is present in all acids?
H+
What ion in present in all alkalis?
OH-
What happens when you add universal indicator to an acid?
It turns red/orange/yellow
What happens when you add universal indicator to an alkali?
It turns blue/purple
What happens when you add universal indicator to a neutral substance?
It goes green
What pH are acids?
1-6
What pH is a neutral solution?
7
What pH is an alkali?
8-14
What is the general equation for neutralisation?
H+ + OH- -> H20
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What do we mean by a strong acid?
An acid that fully dissociates (breaks down) in solution - releasing H+ ions.
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What do we mean by a weak acid?
An acid that only partially dissociates (break down) in solution.
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What are examples of strong acids?
Nitric acid, sulphuric acid, hydrochloric acid
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What are examples of weak acids?
Citric acid (In fruit), Ethanoic acid (in vinegar), carbonic acid (in fizzy drinks)
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What is the link between concentration of an acid and pH?
The HIGHER the concentration of H+ ions in an acid, the lower the pH is.
