C4-chemical Changes Flashcards
What does the pH scale go from
0-14
What does the ph scale measure
How acidic or alkaline a solution is
When the ph of a solution is lower, what does that mean?
More acidic
When the ph of a solution is higher, what does that mean
More alkaline
What ph does a natural substance have
Ph 7
How can you measure the ph of a solution
Ph probe
Indicator
What is an acid
A substance that forms an aqueous solution with a ph less than 7
What is an base
A substance that will react with an acid to form a salt
What is an alkali
A base that dissolves in water to form a solution with a ph greater than 7
When in water what do alkalis form
OH- ions
When in water what does acids form
H+ ions-
What is the reaction between acids and bases called and the equation
Neutralisation
Acid+base=salt+water
Neutralisation can be seen in terms of H+ and OH- ions, what is the equation for this
H+ + OH- = H2O
What are the 4 most reactive elements in the reactivity series from most to least
Potassium
Sodium
Lithium
Calcium
What are the 4 fairly reactive elements in the reactivity series from most to least
Magnesium
Carbon
Zinc
Iron
What are the 2 not very reactive elements in the reactivity series from most to least
Hydrogen
Copper
What is the formation of metal ore
Oxidation = gain of oxygen
What is the extraction of metal
Reduction = loss of oxygen
How are metals above carbon dioxide extracted
By using electrolysis
How are metals below carbon extracted
Reduction with carbon
What is a redox reaction
When electrons are transferred
What is OILRIG stand for
Oxidation is loss
Reduction is gain
Name substance mixed with aluminium oxide and explain why?
Cryolite
Decreases melting point of aluminium oxide
Making it cost less/more eceonomical
What is the colour change here nitric acid is added to the mixture of universal indicator and water
Green to red
What happens to ph of water when nitric acid is added
Decreases
What is state symbol for nitric acid
aq
Explain how oxygen gas is produced in electrolysis of sodium sulphate solution
Water molecules break down to produce OH- ions, which are attracted to the positive electrode, where OH- ions are oxidised
