AQA Chemistry New AS Unofficial Mark Scheme

For the last question, can't quite remember what it was, but it was 3.2 moles of N2 formed right?

What's the observation when colourless Potassium iodide and Sodium Chloride are mixed and what reaction occurred for this to be seen?
There was a brown solution seen, as Iodine ion was reduced to Iodine.

I think I lost around 15-17 marks and hopefully that will be a low A. Now that I finished all my paper 1 exams, I really know what I did wrong for each subject. At C1 I had timing problems and then I improved in C2 and I had 30 mins left. In this exam I lost marks on wasting time on 1 mark question. Now I'm going to work real hard to get high marks for Chem.

Yes I'm fairly certain you formed 3.2 moles in total, (3 from the first reaction and 0.2 from the second). You then multiply by this by Avogadro's constant to find the number of molecules I think and the answer was like 1.93 x 10^24.

If you know anymore questions or answers please reply and the number of marks.
What is the full electronic configuration of Al? 1s2,2s2,2p6,3s2,3p1

What is the full electronic configuration for Cr+3? 1s2,2s2,2p6,3s2,3p6,3d3

What is the formula of the ion with same electronic configuration of Krypton?
Sr2+ (strontium)

What compound has a +2 and -3 ions and has the same number electrons as Argon?
Ca3P2

Which ion has a smaller atomic radius Mg2+ or Na+?
Mg 2+
because has the same number of electrons, same shielding but more protons. So greater nuclear charge and attraction for outer electrons.

What is the first ionisation energy of Na?
Na (g) --> Na+ (g) + e-
Diagram-Mark where the Mg or was it Si?
Was and then mark the point where Sulphur was on the First ionisation graph.
Mg/Si should have been above so the line was increasing.
Sulphur should have been below Phosphorus but above Silicon.

Why does Sulphur have a different first ionisation energy compared to Phosphorus?
-Both have same shielding and in the same orbital the 3p orbital
-Sulphur is paired with an electron in the 3p orbital whilst Phosphorus isn’t
-There’s repulsion between the negatively charged electrons
-So electrons are easier to remove

What is the method of making a standardised solution of 250cm^3? (6 marks)
-Weigh out known mass on weighing boat using a mass scale
-Remember to deduct the mass of the weighing boat to find the exact mass of the solid. (or zero the scale mass)
EDIT: You may not need this part as you've been told the known mass
-Then transfer the contents into a beaker. Use distilled water to make sure all solids are in the beaker.
-Then add bit more distilled water
-Stir with a glass rod to make sure it's all mixed
-Then pour solution into a Volumetric flask using a funnel
-Clean the funnel with distilled water
-Then fill the volumetric flask to the 250cm^3 mark. At near the mark use a pipette to add water dropwise and until meniscus is on the mark line.
Then place stopper on it. Twist the volumetric flask a few times to ensure it's all mixed.

Find mean titre value.
Ignore the first number as it was the rough one when calculating mean.
EDIT: You were only supposed to use 2 values that are 0.1 part when calculating mean.

What was the concentration of the solution.

Student titrated, what should she to improve her methods so there's a smaller percentage uncertainty?
-Titrate a greater volume of solution
-Why? So there's a greater value as percentage uncertainty= uncertainty/value *100. Bigger volume means there's a greater titre value.

Why does Bromine have lower boiling point than Magnesium?
-Bromine has a simple molecular structure.
-There’s weak Van der Waals forces between molecules.
-So smaller amount of energy needed to break these forces.
-Magnesium has a metallic lattice.
-It has many strong metallic bonds.
-Bonds formed from the strong attraction between positiveions and delocalised electrons.
-The metallic bonds are stronger than the Van der Waals forces

How do the ions get accelerated, detected by ToF and how abundanceis measured?
- Accelerated by negative electric field
-The ions reach the detector and generate a small current, which is fed to a computer for analysis. The current is produced by electrons transferring from the detector to the positive ions. The size of the current is proportional to the abundance of the species.

Calculation to find mass of one ion.
1/Avogadro constant * mass. Then divide by 1000 to put it in Kg.
Using kinetic energy, find velocity.
Starts with 1........ Quite a large number.

Draw the spectrum of Br2 with two isotopes of equal abundance.


Suggest why Magnesium has a longer melting point than Bromine. (Something like that?)
-It has much more bonds than Bromine. So more bonds are needed to be broken when melting.
a) Calculate the mass of Ammonia in Q?
Basically use the ideal gas equation and usethe temp given, multiply the pressure by 1000 to convert it to SI Units, divide the volume by a million to convert to m^3 . Then use everything given to find the number of moles in Ammonia. Then find the mass of Ammonia using the mr.
b) Calculate the volume in P given that the temperature decreased by 5 degrees and the total pressure is 75kPa?
-Find volume of the whole system with the new values and use moles from previous question
-Then subtract from the volume of Q given.

Draw NH3 and AlCl3 and write the bonding angle.
NH3- 1 Lone pair and 3 bonding pair. Should have drawn a trigonal pyrimidal.
Bond angle- 107

AlCl3- 3 bonding pair so Trigonal Planar
Bond angle- 120

What type of bond between NH3 and AlCl3 to make 3HNAlCl3?
Dative covalent
Electron pair donated from NH2 to AlCl3.

What is the half equation of Chlorate(I) into Chlorine?
2ClO- + 4H+ +2e- ---> Cl2 + 2H20

What is the redox equation of Sodium Chlorate(I) and HCl?
I have no idea.

What's the observation when colourless Potassium iodide and Sodium Chloride are mixed and what reaction occurred for this to be seen?
There was a brown solution seen, as Iodine ion was reduced to Iodine.

Question on Anhydrous Magnesium Chloride and Anhydrous Barium Chloride mixture. Water was added and Sulphuric acid too. White precipitate was formed. What was this an find percentage of Magnesium in mixture?
Barium Sulphate.
Calculation:

Multiple Choices:
-Brown Colour is from the Reactant and forward is exothermic.
-Empirical of hydrocarbon with 9/11th Carbon- C3H8
-Doubts about biggest dipole. I put down BF3 and checked in my CGP book and states that bonds with electronegativity differences would make a dipole. Others argue that its Carbon one because BF3 is not polar.
-Group 2's ionisation energy decreases downwards
-There's 50cm^3 of gas in the end.
-Gold is 19.3
-SiO2 was Macromolecular
-Balance was 4:7
-The reducing agent was C204
-How much sulphuric acid needed? D
-Heavier isotope took longer in ToF
-H2 Molecules was 1.81* 10^24

How many marks was the justification and improvement of titration question?
Also I got 1740000 for the speed of the particle, would they give a range of answers as there was a lot of rounding that could have been done?

How many marks was the justification and improvement of titration question?
Also I got 1740000 for the speed of the particle, would they give a range of answers as there was a lot of rounding that could have been done?

I think I lost around 15-17 marks and hopefully that will be a low A. Now that I finished all my paper 1 exams, I really know what I did wrong for each subject. At C1 I had timing problems and then I improved in C2 and I had 30 mins left. In this exam I lost marks on wasting time on 1 mark question. Now I'm going to work real hard to get high marks for Chem.

ok, so im on a 50/50 with this paper did anyone else mess up totally on the titration question???????

How did you get that? I got like 12.1 fs

i left 0.69g, i got the next part wrong tho