Edexcel GCSE Chemistry Paper 1
Terms in this set (99)
What is an isotope?
Different forms of the same element with different nunbers of neutrons - so different mass numbers
Relative Mass of a proton?
Relative mass of a neutron?
How to calculate mass number?
protons + neutrons
Number of neutrons?
mass number - atomic number
number of electrons?
Number of protons?
same as number of electrons
What forces are involved in an ionic bond?
strong electrostatic forces
Simple molecular substances are joined by...
Do molecular substances have high or low melting/boiling points?
low - weak intermolecular forces
network of carbon atoms that form 4 covalent bonds
- giant covalent structure
- incredibly hard
network of carbon atoms that form 3 covalent bonds
- giant covalent
- soft and conducts electricity
What is a fullerene?
molecules of carbon shaped like closed tubes (carbon naotubes) or hollow balls (buckminsterfullerene)
Metallic bonding involves...
delocalised electrons - can conduct electricty
How to calculate the number of moles ?
mass in g / relative atomic or formula mass
A pure substance is...
a substance that it made up of a single element or compound
You can test for purity using...
melting / boiling points
What is potable water?
water that is fit to drink
How can you calculate the Rf value ?
distance travelled by solute / distance travelled by solvent
Sources of potable water....
surface water, ground water, waste water
What are the 3 stages of purifying water ?
Filtration, sedimentation, chlorination
What is deionised water?
water that has had the ions in it removed
Acid + Metal Oxide ->
Salt + water
Acid + Metal Hydroxide ->
Salt + water
Acid + metal ->
Salt + hydrogen
Acid + metal carbonate ->
Salt + Water + Carbon dioxide
Which salts are soluble?
sodium, potassium, ammonium
Which chlorides are insoluble?
Which sulfates are insoluble?
lead, barium, calcium
Which carbonates/hydroxides are soluble?
sodium, potassium, ammonium
How can you make soluble salts?
acid+insoluble base of acid/alkali reactions
Positive ions are...
Negative electrode is...
cathode, which attract cations (positive anions)
Negative ions are..
Positive electrode is...
anode, which attract anions (negative ions)
What is electrolysis?
the breaking down of a substance using electricity
Most reactive elements in order ...
Potassium, sodium, calcium, magnesium
Least reactive elements...
Copper, silver, gold
What is reduction in terms of oxygen?
The removal of oxygen
What is oxidation in terms of oxygen?
the addition of oxygen
What is a displacement reaction?
a redox reaction where the more reactive metals displace the less reactive ones
How can metals be extracted?
reduction with carbon (if less reactive) , electrolysis (if more reactive than carbon)
What are biological methods for extracting metals?
Bioleaching (uses bacteria to seperate metals) and phytoextraction (growing plants in soil that contains metal compounds)
What are life cycle assessments?
assessments to show total environmental costs
What are the stages of the life cycle?
Choice of metal, manufacture, product use, disposal
Equilibrium can only be reached if...
the reaction takes place in a closed system
What is Le Chatelier's Principle?
The equilibrium position moves to minimise any changes you make
How does temperature impact equilibrium?
decreased - exothermic direction to produce more heat
increased - endothermic direction to absorb more heat
How does pressure impact equilibrium (gases)?
decreased - moves to side with more moles
increased - move to side with less moles
How does concentration impact equilibrium?
increase reactants - move to the right
increase products - move to the left
What is corrosion?
the process where something is slowly damaged or destroyed by chemical processes
Percentage yield =
(actual yield / theoretical yield) x 100
atom economy =
(total Mr of desired products/ total Mr of all products) x 100
mass / volume
How are alloys made?
adding another element to a metal
What is the molar volume?
the volume occupied by one mole of gas
Molar volume =
gas volume / number of moles
what is empirical formula?
the simplest positive integer ratio of atoms present in a compound
how to make soluble salts?
acid + insoluble base
6.02 x 10^23
metal + non-metal
non-metal + non metal
is used for separating out a liquid from a solution
is used to separate a mixture of liquids
a substance that can conduct electrcity
a reaction in which a substance loses or gains electrons
oxidation occurs at...
reduction occurs at...
which electrode do metal ions go to?
the cathode as metal ions are positive
separates a soluble solid from a substance
what could you do if one of your mixtures in chromatography is insoluble and does not move in the mobile phase?
use a different solvent as this might separate the components of the mixture
how to work out empirical formula?
- find the number of moles
- divide the each number of moles by the smallest number of moles
- find the ratio
ionise almost completely in water
do not ionise fully in a solution
example of a displacement reaction
Ca + ZnSO4 -> CaSO4 + Zn
uses bacteria to separate metals from water and the bacteria will leach out the metal
growing plants in soil with metal compounds. the plants can't remove the metal compounds so they gradually build up in the leaves. the leaves can be harvested.
allows you to find how much acid is needed to neutralise an alkali (or vice versa)
how to work out mass? (abundance)
(Mr x %abundance) + (Mr x %abundance) / 100
groups in a periodic table
tell us the number of electrons on the outer shell
period on the periodic table
tell us how many shells an atom has
what is the empirical formula of a compound that is 75% carbon and 25% hydrogen?
- write down number in question
- write down the mass from the periodic table
- divide number in the question by Ar
- divide both by the smallest number
H + OH = H20
test for chlorine
bleach damp litmus paper
how to make a pure salt (sulfuric acid and copper oxide)
- heat the sulfuric acid
- stir in the copper sulfate until it is an excess (until no more can dissolve)
- let it cool
- filter the solution to remove any excess copper oxide
- evaporate away the liquid
- heat to form crystals (crystalisation)
- pipette 25cm3 of alkali into a conical flask, add phenophathalin indicator
- fill the burette with an acid of known concentration
- take the initial reading on the burette and record it
- while swirling the flask, use the tap too slowly add the acid to the alkali
- when the first permanent colour change happens, i.e. pink -> clear, stop adding the acid
- record the final volume of the burette
- repeat this whole thing again and make sure the results are very similar
P - positive
A - anode
N - negative
i - is
C - cathode
put heat into the reaction
energy will be released
- calculate the number of moles of acid used (concentration x volume)
- use this to find the number of H+ ions involved in the reaction
- this is equal to the amount of OH- ions
- calculate the number of mole of alkali used
- calculate the concentration of the alkali
one mole of gas takes up...
Hydrogen fuel cell
2H2 +02 ->2H20
- hydrogen is being oxidised
- reaction between hydrogen and oxygen produces a current and energy is released
- water is the only product
half equations for the electrodes in the hydrogen fuel cell
Negative electrode (cathode) - 2H2 -> 4H+ + 4e-
Positive electrode (anode) - O2 + 4H+ + 4e- -> 2H20
Advantages and Disadvantages of hydrogen fuel cells
- water is the only waste product
- will work as long as you provide hydrogen
- do not get less efficient
- hydrogen is explosive
- hard to store safely
- hydrogen fuel cells produce a low voltage so several are needed together
substance that reacts with an acid to produce salt and water (neutralisation)
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