Chapter 11 Acids and Bases - Oxides + Neutralisation Flashcards
What is neutralisation
reaction with between alkali and acid that gives water and salt
Where does water come from in neutralisation
The hydrogen ions from the acid and the hydroxide ions from the alkali give water molecules
H+ + OH- —> H2O
How does an acid donate protons
How are the protons accepted
what are formed
The H+ ion of an acid is essentially just a proton (no electrons)
This is donated to the Hydroxide ion.
The hydroxide ions accept the proton to form water molecules
pH and colour of a neutral substancew
pH: 7
colour: green
Real life application of neutralisation
Acidity in soil:
Optimal plant growth requires a soil pH between 5 and 8. Soil pH imbalance to be too acidic reduces plant growth yield. Soil acidity is neutralized by adding lime or powdered limestone.
What are oxides
Compounds containing oxygen and another element
How are basic oxides formed
In general, metals react with oxygen to form basic oxides
What can basic oxides do
They can neutralize acids
How are acidic oxides formed
Non-metals react with oxygen to form acidic oxides
What happens when the acidic oxides are dissolved in water
they give acids
what are amphoteric oxides
define them
amphoteric oxides act as acids and bases.
when presented with an acid they act as a base but when presented with a base they act as an acid
definition: they can NEUTRALISE both acids and alkakis
Amphoteric oxide examples
Al2O3
ZnO
what are neutral oxides
neutral oxides are neither basic nor acidic
examples of neutral oxides
1) Nitrous oxide (N2O)
2) Nitric oxide (NO)
3) Carbon monoxide (CO)
4) Water (H2O)
5) Manganese(IV) oxide (MnO2)
6) Hydrogen peroxide (H2O2)
How to prove that an oxide is amphotheric
Show that the oxide reacts with both an acid and a base to give —> salt + water
Word and Chem Eqns to prove Al2O3 is amphoteric
with acids:
Aluminium Oxide + Hydrochloric acid —> Alumium Chloride + Water
Al2O3 + 6HCl —> 2AlCl3 + 3H2O
with alkali:
Alumium Oxide + Sodium Hydroxide —> Sodium Aluminate + Water
Al2O3 + 6NaOH —> 2Na2AlO3 + 3H2O
Word and Chem Eqns to prove ZnO is amphoteric
with acids:
zinc oxide + hydrochloric acid —> zinc chloride + water
ZnO + 2HCl —> ZnCl2 + H2O
with alkali:
zinc oxide + sodium hydroxide —> sodium zincate + water
ZnO + 2NaOH —> Na2ZnO2 + H2O
if a question states how we could show a compound is an acid without using an indicator what to do
add metal
hydrogen is given off/effervescence
burning splint pops
what problem arises when a compound of a transition element doesn’t include its oxidation number? eg iron oxide
because they have more than one oxidation state, form ions with different charges.
fe2+ and fe3+
what does saturated solution mean
A state of a solution where no more solute can be dissolved in the solution at that given temperature.
What kind of oxide is Calcium Oxide
Process to make it
name colours if any
Basic oxide
heat calcium up
plunge it into a gas jar with oxygen
bursts into an INTENSE WHITE FLAME WITH A TINGE OF RED
and leaves white ash which is calcium oxide
Chemical reaction for making calcium oxide
2Ca (s) + O2 (g) —-> 2CaO (s)
What kind of oxide is Iron (III) oxide
Process to make it
name colours if any
Basic oxide
Heat iron wool
plunge into a jar of oxygen
glows bright and throws out a shower of bright orange sparks
BLACK solid left behind is iron (iii) oxide
Chemical equation of making iron (III) oxide
4Fe (s) + 3O2 (g) —-> 2Fe2O3 (s)
What kind of oxide is Copper (II) oxide
process to make
basic
Copper ‘turnings’ are heated and then a stream of oxygen passes over it
surface turns BLACK which is Copper (II) oxide
Why is the process to make copper (II) oxide different
how are reactivity and oxygen related
Copper too unreactive to catch fire in oxygen
the more reactive the metal is the more vigorously it reacts with oxygen
Chemical eqn to make copper (II) oxide
2Cu (s) + O2 (g) —> 2CuO (s)
What kind of oxide is carbon dioxide
Process to make it
name colours if any
Acidic oxide
Powdered carbon heated over bunsen burner until RED-HOT
plunged into a jar of o2
glows bright RED and forms CO2 gas
Chemical eqn for formation of Carbon Dioxide
C (s) + O2 (g) —> CO2 (g)
What kind of oxide is Sulfur Dioxide
Process to make it
name colours if any
Acidic oxide
Sulfur catches fire over a bunsen burner
burns with a BLUE flame
(burns even brighter in pure oxygen)
forms a gas - sulfur dioxide
Chemical eqn to form sulfur dioxide
S (s) + O2 (g) —> SO2 (g)
