Edexcel Chemistry IGCSE 1C Unofficial Mark Scheme 19th May 2016

I agree but I think they'll make paper 2 harder considering this one wasn't.

I really want to add them in but do you know roughly which question they came in?

I think this exam was a lot easier than previous ones - especially people in my school - so I think they could be raised, but an A* will be around 75-80 %.

what do you think an A will be

do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?

do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?

Empirical formula for Y cannot be CH2......
Y was an alkene it had a double bond, its formula was C3H6. C3H6 was the empirical formula because, they can both be divide by 3 to give CH2 (methene), but methene cannot exist as an alkene MUST HAVE A DOUBLE BOND. CH2 has one carbon therefore it cannot have a double bond and cannot exist.

fizzing (hydrogen is given off) & the solid disappears (it dissolves)

Im pretty sure it is CH2

Im pretty sure it is CH2

Empirical formula for Y cannot be CH2......
Y was an alkene it had a double bond, its formula was C3H6. C3H6 was the empirical formula because, they can both be divide by 3 to give CH2 (methene), but methene cannot exist as an alkene MUST HAVE A DOUBLE BOND. CH2 has one carbon therefore it cannot have a double bond and cannot exist.

woops will i get marks if i said bubbles of hydrogen appeared? lol

methene cannot exist.....

do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?

Question about mass of water is 0.9g of water in CuSO4.5H20

Tell me the questions which I'm missing out - I'll add them in.

1.a)
Condensation. (1)

1.b)
Energy: average ke of particles decreases.
Arrangement: the intermolecular spaces decrease (as some intermolecular
forces between particles start to form).
Movement: particles in liquids slide over each other. (3)

2.a)
Filtration. (1)

2.b)
Arrow drawn into solvent inside beaker.
Arrow drawn onto chromatography paper.
Arrow drawn onto the line on the chromatography paper. (3)

2.c)
There are for 4 dyes present in the substance as the original substance
dissolved into the solvent and 4 dyes were drawn up. (1)

3.a)
Hydrogen molecule bonding - two circles that cross over each other and at the
point of intersection there is a cross and a dot. The circles both have letters H
inside of them. (1)

3.b)
Element in the air - argon. (1)

3.c)
Compound present in unpolluted air - H2O (water) or CO2 (carbon dioxide). (1)

3.d)
Isotopes are atoms with specific number of neutrons independent to the number of protons that defines the element. (2)

3.e)
H1 - 1 proton, 0 neutrons, 1 electron.
H2 - 1 proton, 1 neutron, 1 electron.
H3 - 1 proton, 2 neutrons, 1 electron. (3)

3.f)
Atom with 3 protons - the diagram with 3 dots.
Atom in period 3 - the diagram with 15 dots (phosphorous)
Atom with 15 electrons - diagram with 15 dots (phosphorous)

4.a)
Simple filling in the temperatures - to 1 dp. (4)

4.b)
Max temperature produced by magnesium. (1)

4.c)
Ice used to cool down and condense the water vapour. (1)

4.d)
Products formed - magnesium chloride and hydrogen (gas). (2)

4.e)
Increasing volume of acid to 50cm3 - not so great a rise in temperature as increase in volume of acid means that more energy is required for the same rise in temperature. (2)
4.a)
Copper pile turns black because the oxygen in the air reacts with it in a combustion reaction to form Copper oxide (black solid). (2)

4.b)
The gas is cooled down before it is measured so that its volume can be recorded at rtp (as the original volume had been measured in these conditions). Heated gases = expansion of volume. (1)

4.c)
Why didn't the small heap of copper turn black - because all of the oxygen in the air had been used up in the previous reaction hence no combustion reaction to oxidise copper. (1)

4.d)
Percentage of oxygen - 16.6 (recurring) or 16.7%. (2)

5.a)
In order of reactivity - Q, R, S, P. (4)

6.a)
Graph - draw straight lines of best fit, both lines must intersect. (4)

6.b)
Volume used - 12.5 cm3. (1)

6.c)
33 degrees celcius. (1)

11.a)
Propane. (1)

11.b)
C4H10. (1)

11.c)
W, X, Y. (1)

11.d)
Empirical formula for Y - CH2. (1)

11.d)
A hydrocarbon with a double carbon = carbon covalent bond.
A hydrocarbon is a organic compound made of hydrogen and carbon only. (3)

11.e)
Displayed formula should have only 1 Br atom in it. (1)

11.f)
Condition required - UV light. (1)

16.a)
Draw graph line - steeper and levels off first but at same level. (2)

16.c)
Increase in concentration = increase in particles per unit volume, hence increase in no. of collisions per unit time hence increase in no. of successful collisions per unit time, hence increase in rate of reaction. (3)

For the equation for H2 +O2, the answer is water.
However, would H202 (hydrogen peroxide) be correct