GCSE Chemistry Unit 1H Unofficial MarkScheme

Yes; I wrote 'Repeat experiment for each of the beams several (at least three times) times to detect and discard any anomalous results and calculate the mean.'

That may be correct then.

i. Number of protons and electrons.
ii. Number of protons plus the number of neutrons.

Isn't it
i Number of protons
ii Number of protons+neutrons

Also what question was this for?
iii. The change their properties when there are changes in the environment i.e. they react to heat and temperature.

Hi, These are some answers: they may go into more detail than is necessary (particularly cast iron one) so do be disheartened if you don't have the same!!
These are from my memory so sorry if any are wrong - these were made with a lot of different people who remember different parts of it!!!!!

1. .
a. .
i. Number of protons and electrons.
ii. Number of protons plus the number of neutrons.
b. This is because they have the same number of positively charged protons in the nucleus, as the number of negatively charged electrons in their shells.
c. This is because they have the same number of electrons in their outer-most shell (7 electrons in their outermost shell) and thus have similar chemical properties.
d. Sulphur
e. .
i. Ions (ionically bonded).
ii. Molecules (covalently bonded)
2. .
a. .
i. Carbonate.
ii. Decomposition.
iii. Water.
iv. Alkali.
b. .
i. On exam.
ii. They could use smaller intervals so that there will be more points plotted on the graph meaning that the line of best fit will be more accurate and thus producing a more accurate and reliable trend in their conclusion. (could be other answers) - this one could be wrong; it may be to do with changing the weights and using smaller weights and thus...
iii. 42 newtons (range of answers will be accepted).
iv. He is partially correct because, up until around 400 grams, as the mass increases so does the force needed as for 400 grams, 150 newtons are needed. However, after 400 grams, the force needed begins to decrease as for 700 grams, the force needed is 100 newtons.
3. .
a. This is because there is a lack of valid and reliable evidence – forming, in some cases, conflicting evidence - for many people to come to an accurate and complete theory to be able to definitely say how the earth was formed.
b. In the early atmosphere billions of years ago, it is thought that, due to intense volcanic activity, in the Earth’s atmosphere, there was a lot of carbon dioxide, water vapour and small proportions of methane and ammonia. However, over this changed.
As the Earth’s atmosphere began to cool down, the water vapour in the air condensed to form oceans. This caused a lot of the carbon dioxide within the air to be dissolved into the water and thus removing a lot of it from the atmosphere. Moreover, a lot of the carbon within the water, overtime, became carbonate. This then formed parts of the shells and skeletons of the sea creatures within the ocean. When they died, they became sedimentary rocks, thus locking up a lot of the carbon. Furthermore, when algae and plants came into existence, they were able to undergo a process named photosynthesis. Photosynthesis is a process which encompasses Carbon Dioxide converting into Oxygen. This meant that, as the years went by, there was a reduction in amount of Carbon Dioxide and increase amounts of oxygen.
As a result of all of this, the atmosphere is around 80% nitrogen and 20% oxygen, however there are small proportions of carbon dioxide, water vapour and noble gases. This number is changing. This because, from the exponential rapid population increase of the human population, fossil fuels – made up of carbon and dead, fossilised plants and animals – are being used to generate electricity. This means that, at the moment, the increase rate in these being burnt has resulting in an increase in Carbon Dioxide in our atmosphere.
1. .
a. This is so that the ore is concentrated meaning that the metal produced will be purified, ridding of any impurities found within the ore. This is why you are separating so that when the metal is extracted, no impurities will be within.
b. .
i. It is quite brittle and thus it can easily break.
ii. Cast iron is heated in a furnace in the presence of oxygen, so that it can form an alloy with carbon to produce steel. At the high temperature at the bottom of the furnace, carbon dioxide reacts with carbon to produce carbon monoxide. It is the carbon monoxide which is the main reducing agent in this part of the furnace. In the hotter parts of the furnace, the carbon itself also acts as a reducing agent. As the cast iron is heated, the carbon and, in some parts of the furnace, the carbon monoxide react with the cast iron entering the furnace to form the alloy steel. The temperature of the furnace is hot enough to melt the steel which trickles down to the bottom where it can be tapped off.
c. .
i. It is less dense.
ii. Aluminium is found in group three meaning it has only 3 electrons in its outer-most shell. Moreover as it is in this certain group, its charges of its ions can have only one set charge. However copper is not in any numbered group but in group which is between group 2 and 3, meaning that copper can have ions with different charges and thus is a transition metal. Furthermore, within the group that it in, it is surrounded by only transition metals.
iii. As iron is more reactive than copper, the scrap iron can displace the impurities within the copper ions so that the copper produced will be pure. An example equation could be iron + copper sulphate → iron sulphate + copper
2. .
a. Crude oil enters a fractionating column is hot vapour which has been heated up to around 350oC. At the top of the column it is cooler and towards the bottom it is hotter. As the hydrocarbons within the crude oil all have different boiling points, the long chain hydrocarbons with the highest boiling points will be separating out the bottom of the column, the rest of the hydrocarbons rise up through the column as a hot vapour. When the hydrocarbons reach a certain temperature which is their boiling points, the gases will condense into their liquid forms and be separated into fractions.
b. The carbon dioxide will react with the limewater to produce calcium carbonate meaning that there will be less carbon dioxide released into the atmosphere. This will have a positive impact on the environment, as it will reduce the rate at which global warming is occurring. Moreover, as water vapour contributes to this problem, there is a high possibility that the water vapour as, for the limewater to be in liquid form, it will have to be at a certain temperature which will cause the water vapour to condense thus, on a whole, reducing the impact of global warming on the environment from the reduced rate caused.
c. .
i. C2H4
ii. On exam paper.
iii. The change their properties when there are changes in the environment i.e. they react to heat and temperature.
3. .
a. .
i. They have a high boiling point, thus they provide a lot of energy.
ii. Plant Material is crushed and the oil is removed by pressing or distillation; water and other impurities are removed.
b. This is because the vegetable oil has a higher boiling point than water. This means that it will be able to withstand higher temperatures when cooking, rather than just boiling with water. Moreover, it not only means that vegetable oil will be able to cook to food quicker than water, it will also add extra flavour and increase the energy content a person will intake, as opposed to cooking/boiling with water.
c. Its head is hydrophilic and the tail is hydrophobic – the emulsifier is negative charge.
The ‘tail’ dissolves in the oil making tiny droplets. The surface of each oil droplet is charged by the ‘heads’ sticking out into the water. As the head is negatively charged, the like charges repel each other. This keeps them spread throughout the water, stopping the oil and water separating into two layers.

The 1st question was, "what is an atomic number" - Atomic number is the number of protons.

The 2nd part to the question was, "what is the mass number" - search it on google if you don't believe me

It should be the number of protons OR the number of electrons. The word "and" suggests their sum.....

I'm pretty sure loads of people drew there line of best fit wrong, mine went through all the points? Did I do it wrong

how did everyone draw the lines of best fit?