C4: Chemical Changes (triple) Flashcards
What is the word equation for neutralisation reaction of an acid and base?
Acid + Base —> salt + water
What do acids do in aqueous solutions?
Ionise
Produce a H+ ion (proton)
Describe the properties of a weak acid.
Don’t ionise fully
Ionisation is a reversible reaction
Creates an equilibrium between the undissociated and dissociated acid
Describe the properties of a strong acid.
Ionise completely in water
More reactive than weak acids because they have a higher concentration of H+ ions
What is Ph?
The measure of concentration of hydrogen ions.
For every 1 decrease in Ph H+ ions increase by 10 times.
How do acids react with metal oxides?
Form salt and water
How do acids and metal hydroxides react?
Form salt and water.
How do acids and metal carbonates react?
To form salt water and carbon dioxide.
What is the reactivity series of metals?
Potassium Sodium Lithium Calcium Magnesium Carbon Zinc Iron Hydrogen Copper
How do acids react with metals?
Salt + hydrogen
How are metal ores formed?
Metal is oxidised (gains oxygen)
How are metal extracted? (Redox)
Metal is reduced (loss of oxygen)
What is oxidation?
Oxidation Involves Loss of electrons Reduction Involves Gain of electrons
What is reduction?
Oxidation Involves Loss of electrons Reduction Involves Gain of electrons
Describe a diagram of a simple electrochemical cell.
copper and zinc electrodes are connected by a wire and are suspended in sodium chloride solution (electrolyte).
What can give cells different voltages?
a greater difference in reactivity between the electrodes will create a bigger voltage.
the electrolyte used.
Explain what happens to the voltages of cells when they are connected in series?
their voltages are added up.
Why can non rechargeable batteries only be used once?
all the reactants in the cells are used up and the reaction wasn’t reversible.
How does the reaction between oxygen and a fuel in a fuel cell create usable electricity?
the fuel is oxidised in the fuel cell setting up a potential difference.
How is a hydrogen fuel cell a redox reaction
hydrogen loses an electron (oxidised) in the anode compartment. oxygen gains electrons (reduced) in the cathode compartment.
