1What is an acid?
An acid is a source of hydrogen ions, H⁺
2What is an alkali?
An alkali is a source of hydroxide ions, OH⁻
3Describe the pH scale
0-6=acid
7=neutral
8-14=base
4What colour is acid, alkali and neutral on litmus paper?
acidic= red
neutral=purple
alkali=blue
5What colour is acid, alkali and neutral in methyl orange?
acid= red
alkali= yellow
neutral= yellow
6What colour is acid, alkali and neutral in phenolphthalein?
acid= colourless
alkali= pink
neutral= colourless
7What's the link between pH and concentration in acids?
The higher the concentration of hydrogen ions , the lower the pH
8What's the link between pH and concentration in alkalis?
The higher the concentration of hydroxide ions, the high the pH
9What happens when hydrogen ion concentration in a solution increases by factor 10?
the pH of the solution increases by 1
10Define dilute solution
A solution with a high water concentration, but low solute concentration
11Define concentrated solution
a solution containing a large amount of solute
12Explain weak acids
They have at least one H+ that does not completely ionize
13Explain strong acids
They have at least one H+ that completely ionizes
14What is a base?
Any substance that reacts with an acid to form a salt. An alkali is a soluble base
15Acid+ metal
salt + hydrogen
16Acid+metal oxide
salt+water
17Acid+metal hydroxide
salt+water
18Acid+metal carbonate
salt+water+carbon dioxide
20How to test for hydrogen
A lighted wooden splint makes a popping sound in a test tube of hydrogen.
21How to test for carbon dioxide
Turns limewater cloudy
22What's the neutralisation reaction?
A reaction between an acid and a base
23Explain a acid+alkali neutralisation
A reaction in which hydrogen ions from the acid react with hydroxide ions from the alkali to form water
24Why is an excess reactant added when preparing a soluble salt?
To ensure all the reactant has reacted with the acid
25Why is the excess reactant removed when preparing a soluble salt?
To get a solution containing only the salt and water
26Why must titration be used when preparing soluble salts from an acid and soluble reactant?
There in no insoluble reactant that can be removed in filtration
27General rules of common substances in water
All nitrates are soluble
Common chlorides are soluble except silver and lead
Common sulfates are soluble except Lead, Barium and Calcium
Common carbonates and Hydroxides are insoluble except Sodium, Potassium and Ammonium
28How to prepare an insoluble salt
The precipitate can be filtered, washed with water on the filter paper and then dried in an oven.