156 terms

Edexcel CS - Chemistry Paper 2

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Group 1
Which group on the Periodic Table is referred to as the alkali metals?
Group 7
Which group on the Periodic Table is referred to as the halogens?
Group 0
Which group on the Periodic Table is referred to as the Noble Gases?
Soft and have relatively low melting points
Give two physical properties of the alkali metals
The metal floats around on the surface, bubbles of gas are produced, heat is released
What happens when the alkali metals react with water?
Reactivity increases as you go down group 1
What happens to reactivity as you go down group 1?
They lose an electron to form a 1+ ion
What happens to atoms of group 1 elements when they react?
They have a full outer shell of electrons
Why are the Noble Gases chemically inert?
They are inert, have low flammability and have low density
Give three properties of the Noble Gases?
boiling point increases as you go down group 0
What happens to boiling point as you go down group 0?
pale green gas
Describe chlorine at room temperature
red-brown liquid
Describe bromine at room temperature
grey solid
Describe iodine at room temperature
boiling point increases as you go down group 7
What happens to boiling point as you go down group 7?
Damp blue litmus paper turns red and then bleaches
What is the chemical test for chlorine?
a metal halide
What is formed when a halogen reacts with a metal?
a hydrogen halide
What is formed when a halogen reacts with hydrogen?
they dissolve to produce acidic solutions
What happens to hydrogen halides in water?
Reactivity decreases as you go down group 7
What happens to the reactivity of group 7 as you go down the group?
They gain an electron to form a 1- ion
What happens to atoms of group 7 elements when they react?
Compounds that contain hydrogen and carbon atoms only
What are hydrocarbons?
hydrocarbons
What is crude oil a mixture of?
Hydrocarbon molecules where the carbon atoms are in chains or in rings
What sort of molecules are there in crude oil?
fuels and feedstock for the petrochemical industry
What does crude oil provide?
fractional distillation
What process is used to separate crude oil?
domestic heating and cooking
What are gases from crude oil used for?
fuel for cars
What is petrol used for?
fuel for aircraft
What is kerosene used for?
fuel for some cars and trains
What is diesel oil used for?
fuel for large ships and in some power stations
What is fuel oil used for?
to surface roads and roofs
What is bitumen used for?
gases, petrol, kerosene, diesel oil, fuel oil, bitumen
Name the fractions from fractional distillation of crude oil from the top to the bottom of the column
number of carbon and hydrogen atoms in the molecules, ease of ignition, viscosity, boiling points
How do hydrocarbons in different fractions differ from each other? (4 things)
alkanes
Give an example of a homologous series
a series of compounds which: have the same general formula, differ by CH2 in molecular formulae from neighbouring compounds, show a gradual variation in physical properties, e.g. boiling points & have similar chemical properties
What is a homologous series?
CnH2n+2
What is the general formula of alkanes?
methane
Name the alkane with the molecular formula CH4
C2H6
What is the molecular formula of ethane?
propane
Name this alkane
water and carbon dioxide are produced and energy is released
What happens during the combustion of hydrocarbon fuels?
carbon and carbon monoxide
What can be produced from the incomplete combustion of hydrocarbons?
there is not enough oxygen to fully oxidise all of the carbon atoms to produce carbon dioxide
Why can the incomplete combustion of hydrocarbons produce carbon and carbon monoxide?
It combines with haemoglobin in red blood cells which stops oxygen from being transported around the body
How does carbon monoxide behave as a toxic gas?
Soot can block pipes carrying waste gases away from an appliance, cause breathing problems if inhaled and blacken buildings
What problems can soot (unburnt carbon) cause?
sulfur impurities in the fuel combine with oxygen
Why is sulfur dioxide produced when hydrocarbons burn?
sulfur dioxide dissolving in rain water
What is the major cause of acid rain?
crops don't grow well, insects die, fish eggs don't hatch, buildings are weathered, metals corrode more quickly
What problems can acid rain cause? (5 things)
In the high temperatures inside the engine, nitrogen and oxygen react together.
How are oxides of nitrogen produced in cars?
The combustion of hydrogen doesn't produce carbon dioxide which is a greenhouse gas. Hydrogen can be produced relatively easily. Hydrogen is easy to ignite.
Give advantages of using hydrogen rather than petrol as a fuel in cars
Hydrogen is a gas at room temperature and so is difficult to store in large amounts unless it is compressed or cooled so that it becomes a liquid.
Give disadvantages of using hydrogen as a fuel in cars
the breaking down of longer chain hydrocarbons into smaller ones, some of which are unsaturated
What is cracking?
It produces more useful molecules
Why is cracking needed?
an unsaturated hydrocarbon
What is an alkene?
CnH2n
What is the general formula of alkenes?
ethene
What is the name of this molecule?
C3H6
What is the molecular formula for propene?
alkenes
Which hydrocarbon homologous series contains carbon-carbon double bonds?
by gases released from volcanic activity
How was the Earth's early atmosphere formed
little or no oxygen, a large amount of carbon dioxide, water vapour, small amounts of other gases
What did the Earth's early atmosphere contain?
condensation of water vapour
How were the oceans formed?
it dissolved as the oceans formed
How did the amount of carbon dioxide from the early atmosphere decrease?
by photosynthesis of primitive plants
How did the amount of oxygen in the atmosphere increase?
a glowing splint relights
What is the chemical test for oxygen?
gases in the atmosphere absorb heat radiated from the sun
What is the greenhouse effect?
carbon dioxide, methane and water vapour
Give examples of greenhouse gases
correlation between carbon dioxide emissions and temperature change
What evidence is there that human activity has caused climate change?
the location of measurements and the accuracy of historical data
What are the problems with data suggesting that human activity has caused climate change?
rising sea levels, extinction of species as their habitat changes, more extreme weather events, coral 'bleaching'
What are the possible effects of climate change?
Measuring the volume of gas produced or measuring the time taken for a colour change to happen
Give two ways of measuring the rate of reaction
Particles must collide with sufficient energy
What has to happen for a reaction to occur?
Increase the frequency and/or energy of collisions
How can the rate of a chemical reaction be increased in terms of collisions?
increase the temperature, increase the surface area, increase the concentration, increase the pressure
How can the rate of a chemical reaction be increased practically?
The rate of reaction is high
If a rate of reaction graph is steeper what does that mean?
The line levels off (is horizontal)
How can you tell from a rate of reaction graph that the reaction has stopped?
It reduced the activation energy so more collisions are successful
How does a catalyst increase the rate of a reaction?
a substance that speeds up the rate of a reaction without altering the products of the reaction, being itself unchanged chemically and in mass at the end of the reaction
What is a catalyst?
The minimum amount of energy that colliding particles need to have for a reaction to happen
What does the term activation energy mean?
a biological catalyst
What is an enzyme?
the production of alcoholic drinks
Give a use of enzymes
exothermic reaction
What word describes a chemical reaction where the surroundings get hotter?
a reaction where heat energy is given out
What is an exothermic reaction?
endothermic reaction
What word describes a chemical reaction where the surroundings get colder?
a reaction where heat energy is taken in
What is an endothermic reaction?
dissolving, precipitation, neutralisation and displacement
Give four examples of reactions that involve changes in heat energy
endothermic
Is bond breaking exothermic or endothermic?
exothermic
Is bond making exothermic or endothermic?
Exothermic
If more heat energy is released in forming bonds in the products than is required in breaking bonds in the reactants what sort of reaction is it?
Endothermic
If less heat energy is released in forming bonds in the products than is required in breaking bonds in the reactants what sort of reaction is it?
exothermic
Is this an exothermic or endothermic reaction?
...
Draw the energy level diagram for an endothermic reaction
sub-atomic particles were discovered
Why did the Dalton model of the atom change over time?
protons and neutrons
Which sub-atomic particles are in the nucleus?
in shells around the nucleus
Where are electrons found?
+1
What is the relative charge of a proton?
0
What is the relative charge of a neutron
-1
What is the relative charge of an electron?
1
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1/1835 (negligible)
What is the relative mass of an electron?
very small
How big is the nucleus compared to the overall size of the atom?
concentrated in the nucleus
Where is most of the mass of an atom?
the number of protons + the number of neutrons
What is meant by the term 'mass number'?
they contain the same number of protons
What do atoms of an element have in common?
Atoms of an element with the same number of protons but a different number of neutrons
What is an isotope?
because of the existence of isotopes
Why are relative atomic masses of some elements not whole numbers?
properties of elements and their compounds
What did Mendeleev use to make his Periodic Table?
in terms of increasing atomic mass
How did Mendeleev think he had arranged the elements?
a row going across
What is a period on the Periodic Table?
a column going down
What is a group on the Periodic Table?
in order of increasing atomic number
How are elements arranged in the Periodic Table?
they have the same number of electrons in their outer shell and similar properties
What is true about elements in the same group in the Periodic Table?
1
If an element is in group 1, how many electrons are there in the outer shell?
2
If an element is in group 2, how many electrons are there in the outer shell?
3
If an element is in group 3, how many electrons are there in the outer shell?
6
If an element is in group 6, how many electrons are there in the outer shell?
7
If an element is in group 7, how many electrons are there in the outer shell?
by the transfer of electrons
How are ionic bonds formed?
an atom or groups of atoms with either a positive or negative charge
What is an ion?
+
If an element is in group 1, what will the charge on the ion be?
2+
If an element is in group 2, what will the charge on the ion be?
2-
If an element is in group 6, what will the charge on the ion be?
-
If an element is in group 7, what will the charge on the ion be?
oxygen
If the name of a compound ends in -ate, which element must it contain?
OH-
What is the formula for a hydroxide ion?
a giant ionic lattice
What is the structure of an ionic compound?
strong electrostatic forces (ionic bonds)
What holds together an ionic compound?
a metal ion and a non-metal ion
What are ionic compounds made from?
a positive ion
What is a cation?
a negative ion
What is an anion?
positive ions (cations)
What sort of ions do metals form?
negative ions (anions)
What sort of ions do non-metals form?
a shared pair of electrons between atoms
What is a covalent bond?
covalent bonding
What sort of bonding results in the formation of molecules?
100 pm (1 x 10^-10 m)
Approximately how big is an atom?
200 pm (2 x 10^-10 m)
Approximately how big is a molecule?
...
Draw a dot-cross diagram to show the bonding in hydrogen molecules.
...
Draw a dot-cross diagram to show the bonding in hydrogen chloride molecules.
...
Draw a dot-cross diagram to show the bonding in water molecules.
...
Draw a dot-cross diagram to show the bonding in methane molecules.
...
Draw a dot-cross diagram to show the bonding in oxygen molecules.
...
Draw a dot-cross diagram to show the bonding in carbon dioxide molecules.
high because of the strong electrostatic forces between the ions
Are the melting and boiling points of ionic compounds high or low and why?
low because of the weak inter-molecular forces between the molecules
Are the melting and boiling points of covalent (simple molecular) compounds high or low and why?
only when molten or dissolved, not when solid
Do ionic compounds conduct electricity?
no
Do covalent compounds conduct electricity?
carbon
Which element are diamond and graphite made from?
3 bonds
How many bonds does each atom form in graphite?
4 bonds
How many bonds does each atom form in diamond?
large molecules containing chains of carbon atoms
What do simple polymers consist of?
poly(ethene)
Give an example of a polymer
they are malleable and can conduct electricity
Give two properties of metals
mass
What must be conserved in a chemical reaction?
add up all the relevant relative atomic masses
How can you calculate relative formula mass?
the Avogadro constant number of particles of that substance or a mass of 'relative particle mass' g.
What is the definition of a mole?
6 x 10^23 atoms, molecules, formulae or ions
What is the Avogadro constant?
g dm^-3
What are the units for concentration?