C4 Chemical Changes Flashcards
What is reactivity?
How chemically reactive a metal is. When added to water some metals have high reactivity and react very vigorously and other metal barely react because they have low reactivity
What is the reactivity series?
Places metals in order of reactivity
What is the order of reactivity?
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold
How do potassium, sodium, lithium and calcium react with water?
Fizzes, give off hydrogen gas
How do magnesium, aluminium, zinc and iron react with water?
Reacts very slowly
How do lead, tin, copper, silver, gold react with water?
No reaction
How do potassium, sodium and lithium re at with acid?
Explodes
How do calcium, magnesium, aluminium, zinc and iron react with acid?
Fizzes, gives of hydrogen gas.
How do tin and lead react with acid?
Reacts slowly with WARM acid
How do copper, silver and gold react with acid?
No reaction
Which metals can be extracted via electrolysis?
Potassium, sodium, lithium, calcium, magnesium, aluminium
Which metals can be extracted by reduction with carbon?
Zinc, iron, tin, lead
Which metals can be extracted by mining from the Earth’s crust?
Copper, silver, gold
What is oxidation in terms of oxygen?
Gains oxygen in a reaction
What is reduction in terms of oxygen?
Loses oxygen in a reaction.
What is a displacement reaction?
A more reactive element takes the place of a less reactive element
What does a metal’s reactivity depend on?
How readily it forms an ion by losing electrons
What are steps for writing an ionic equation?
Check symbol equation is balanced
Identify all aqueous ionic compounds
Write those compounds out as ions
Remove spectator ions
What is a half equation?
Shows half of the ionic equation in terms of electrons
What is oxidation in terms of electrons?
The loss of electrons
What is reduction in terms of electrons?
The gain of electrons
What substance releases H+ ions?
Acids are compounds that, when dissolved in water, release H+ ions
What are the three main acids?
Sulfúrico acid, Nitric acid, Hydrochloric acid
What is the symbol for sulfuric acid?
H2SO4
What is the symbol, for nitric acid?
HNO3
What is the symbol for hydrochloric acid?
HCl
What substance release OH-?
Alkalis are compounds that, when dissolved in water, release OH- ions
What is the pH scale?
A measure of acidity and alkalinity which runs from 0 to 14
Which solutions are acidic?
<7
Which solutions are alkaline?
> 7
Which solutions are neutral?
7
What is a logarithmic scale?
As the pH scale increases by 1 the number of H+ ions decreases by 10x and the number of OH- ions increases by 10x
What is universal indicator?
Can tell us the approximate pH of a solution
What is an electronic pH probe?
Tell us the exact pH of a solution
What is a strong acid?
When dissolved in water, every molecule splits up into ions - they are completely ionised e.g sulfuric, nitric, hydrochloric
What is a weak acid?
Only a percentage of their molecules split up into ions when dissolved in water - they are only partially ionised e.g ethanoic, citric, carbonic
What is concentration?
How much of a substance there is dissolved in water
What is a concentrated acid?
Lots of acid in small volumes of water
What is a less concentrated acid?
Little acid in a large volume of water
How are salts formed?
When acids react with metals or metal compounds, they form salts
What salt does hydrochloric acid produce?
Chloride salt
What salt does nitric acid produce?
Nitrate salt
What salt does sulfuric acid produce?
Sulfate salt
What does a reaction of acid with a metal produce?
Metal Salt + hydrogen
What does a reaction of acid with a metal hydroxide produce?
Metal salt + water
What does a reaction of acid with a metal oxide produce?
Metal salt + water
What does a reaction of acid with metal carbonate produce?
Metal salt + water + carbon dioxide
What type of reaction is the reaction of acids with metals?
Redox
What is neutralisation?
Bases neutralise acids to form water in neutralisation reactions. Some metal hydroxides dissolve in water to form alkaline solutions called alkalis.
Some metals and metal hydroxide do not dissolve in water. They are bases but are not alkalis.
What is crystallisation?
Chose the correct acid and base to produce the salt
Put some of the dilute acid into a flask. Heat gently with a Bunsen burner
Add a small amount of the base and stir
Keep adding the base until no more reacts and it is in excess
Filter to remove unreacted base
Add the remaining solution to an evaporating dish
Use a water bath to evaporate the water. Salt crystals will be left behind
What does redox stand for?
Reduction and oxidation
What is a spectator ion?
An ion that does not change charge
What is the method for making soluble salts?
Measure out 10cm^3 acid
Add acid to boiling tube in hot water bath
Add base to acid until powder remains after stirring (excess)
Filter the solution
Use an evaporating basin to evaporate the solution
Pat crystals dry
