Topic 4 - Chemical Changes Flashcards
Acid + _____ = salt + ______
Base
Water
List the reactivity series in order from most to least reactive?
- K
- Na
- Li
- Ca
- Mg
- C
- Zn
- Fe
- H
- Cu
Metal + Oxygen = __________
Metal + Oxygen = Metal oxide
Metal oxide = ________ + ________
Metal oxide = Metal + Oxygen
Metal + Water = ______ + ______
Metal + Water = Metal hydroxide + Hydrogen
Does the ability to form positive ions increase or decrease down the reactivity series ?
Decreases down the reactivity series
What is OIL RIG?
Oxidation is loss of electrons
Reduction is gain of electrons
What does the reactivity of a metal depend upon?
Reactivity of a metal depends on its ability to lose electrons and form positive ions
What ions do acids produce in an aqueous solution?
H+ ions
What ions do alkalis produce in aqueous solutions ?
OH-
What are alkalis ?
Bases that are soluble in water
What does a base or an alkaline do ?
It neutralises acid
What colour is ph7 on the universal indicator ?
Green
What colour are acids on a universal indicator ?
Red
What colour are alkalis in universal indicator ?
Purple
Acid + Metal = _____ + _____
Acid + Metal = Salt + Hydrogen
Acid + Metal carbonate = _____ + _____ + _____
Acid + Metal carbonate = Salt + H2O + CO2
What are the differences between a strong and weak acid ?
Strong acid - Fully ionise in aqueous solutions
Weak acid - Partially ionise in aqueous solutions
What are 3 examples of a strong acid ?
HCl
H2SO4
HNO3
What are 3 examples of weak acids ?
- Carbonic acid
- CH3COOH
- Citric acid
Why do strong acids have a lower pH than weak acids ?
As they fully ionise do more H+ ions are in the solution meaning it is more concentrated
What is 1 order of magnitude in pH value ?
As the pH decreases by 1 , concentration of H+ ions increases by 10x
What is the concentration of an acid ?
It is the amount of acid molecules in a given volume of solution
What will be produced at the anode if an aqueous solution contains halide ions ?
The halogen will be produced (group 7)
What do H2O molecules ionise to form ?
H+ and OH- ions
What will be produced at the cathode if the metal is more reactive than hydrogen ?
Hydrogen will be produced
Why is electrolysis expensive ?
- lot of energy required
- lot of energy required to produce an electric current
Why should the anode be replaced regularly?
As O2 reacts with graphite at very high temps which forms CO2
