Topic 4 - Chemical changes Flashcards
If a metal is more reactive - what two things may its properties be?
A more vigorous reaction
It loses electrons more easily in reactions to form positive ions
What is a displacement reaction?
A reaction where a more reactive metal replaces a less reactive one.
What is reduction and oxidation?
Reduction is gain of electrons
Oxidation is loss of electrons
What are the half equations for the reaction of magnesium and copper sulfate solution?
Mg –> Mg2+ + e2-
Cu2+ + 2e- –> Cu
Name 2 extraction methods
Electrolysis
They can be reacted with carbon if they are less reactive (displacement)
What is electrolysis?
Passing an electric current through a solution to separate the elements
How does electrolysis work?
Electrodes are placed into water with an ionic substance in it. The metal ions move to the negative electrode and non metal ions move to the positive.
What is a neutralization reaction?
A reaction where the positive hydrogen ions from the acid react with negative hydroxide ions from the alkali to form water.
What is the reaction of acids with metals?
Metal + Acid –> Salt + Hydrogen
How do you make a soluble salt from an insoluble base?
Warm the dilute acid with a Bunsen Burner
Add the base - a bit at a time - until no more reacts.
Filter the excess solid to get the salt
Heat this using a water bath to get solid crystals
What is the concentration?
The measure of how ‘crowded’ the particles are
What is meant by dilute?
A substance with a small amount of dissolved solute
What is a strong acid?
An acid which completely ionises in a solution
What is a weak acid?
An acid which partially ionises in a solution
What happens when a hydrogen ion concentration increases?
If the hydrogen ion concentration in a solution increases by a factor of 10, the pH of the solution decreases by 1 unit.
