Year 12s: what will be the first way you research your future options? >>

OCR Chemistry Salters B F331 27th May 2016 (Old specification)

Scroll to see replies

I said because its electron configuraton outer shell is the p shell? so its a p block element? not entirely sure if thats what they were looking for

That's probably correct. I nearly put that but then I decided to put because they were compounds with covalent bonds. I have no idea if that is correct though

Reply 201

AmalMohamed98

What did you guys write for the safety hazard with the NO2?

Reply 202

Daniel9998

Original post by _MAT_

They're covalent compounds and covalently bonded compounds are located on the right of the periodic table

pretty sure it said in regards to atomic structure, therefore number of electrons in the outer shell. If it has a higher number of electrons in its outer shell then its further to the right of the table

Reply 203

Daniel9998

Original post by AmalMohamed98

What did you guys write for the safety hazard with the NO2?

place a cover and avoid inhaling NO2 as its toxic

Reply 204

geor_thor

I put wear a breathing apparatus as nitrogen dioxide is toxic

Reply 205

George212

Anyone remember what the the 1 marker was after the density calculation ?

Reply 206

Randomsher789

Original post by Kaz_96

These were my calculation answers, in order of how they appeared in the q paper
Mass of air: 834.7
Mass of air for 1g of C4H10O: 11.28
Energy Density: 36200
Hess' Law: +41
KNOW: 34.15%

Not sure if theyre right but lemme know if you got the same/different

I got all these answers just rounded some to 3 sf

Reply 207

Kaz_96

Original post by Randomsher789

I got all these answers just rounded some to 3 sf

Glad to hear! Hopefully that means we've got them all right haha

Reply 208

uhasan1

does the sign matter for the enthalpy question where the answer is 41 i put minus but i know its plus
Sometimes the mark schemes say ignore sign?
and for the N02 question i put more than one thing down i put mask, gloves googles as NO2 is toxic would i get a mark

Reply 209

uhasan1

after the two calculations questions on the first page wat was the answer for the question below it??
i put less oxygen so incomplete combustion
and how many marks was the percentage decompsition question worth

Reply 210

baymay

For the nitrogen oxide safety precaution, i put that it contributes to photochemical smog which irritates eyes so wear goggles.

Reply 211

Fishhy34

what did you name the two alcohols, and how many marks was the calculations questions?

Reply 212

JgR1997

So these are the questions I can remember, they probably aren't in order.
1. What is a structural isomer (1)
2. Draw two skeletal formulas for two isomers of butanol and give their name (2)
3. Some aren't alcohols what are they? (1)
4. Define what octane number measures? (1)
5. Calculation again (1)
6. Calculation again (1)
7. Maybe something about complete combustion? (1)
8. Density calculation (3)
9. Advantage of using biodiesel over petrol from crude oil (1)
10. Alpha decay of Uranium (2?)
This is where it starts becoming a blur and isn't going to be in order
11. Magnesium and water (2)
12. Trends of carbonates from table and experiment to test this (4)
13. Ionic bonding between two elements (1?)
14. Properties of ionic, simple and lattice covalent (2?)
15. Diagram of metallic bonding (2?)
16. Cracking of decane (1)
17. Isomer of the benzene things (1)
18. What homologous group belong to? (1)
19. Define heterogenous and catalyst (2)
20. Hess cycle calculation (1?)
21. Hess cycle diagram (2)
22. Zeolites how they seperate two compounds (2)
23. Product of reforming (1)
24. SiO4 bond angle and all that jazz (3)
25. Shape of this molecule diagram (1)
26. Energy levels (4)
27. Why each element can be identified uniquely (1)
28. Difference and similarity between emission and absorption (2)
29. Increasing frequency which way (1)
30. History of atom letter order (1)
31. Precaution they should take (1)
32. Explain why entropy increases (2/3?)
33. Enplain why the two elements are where they are in terms of atomic structure (1)
34. Percentage of the moles (2/3?)
35. Man made pollutant produced from zinc fireworks (1)
36. Use of polystyrene cup (1)
37. Why value in data book is different (1)
Okay I think that's all the questions, if all the max marks are correct it adds up to 60.

(edited 7 years ago)

Reply 213

baymay

Original post by sam2222

Ok i will make a list questions and answers I remember:

1. What does heterogeneous and catalyst mean (2)
-Catalyst and reactants are at different physical state. Catalyst speeds up the rate of reaction and can be recovered chemically unchanged at the end of the reaction
2. Write equation for reaction Mg + water (2)
- Mg(s) + 2H2O(l) ---> Mg(OH)2 (aq) + H2(g)
3. what is octane number in fuel (2)
- measure of the fuels tendency to auto ignite , the higher the more efficient the fuel
4. Explain how emission spectra are formed (4)..
- Electrons drop to lower energy levels
- emit light/photon
- energy level proportional to freq , e=hv

5. explain why spectra can be used to identify different element in fire works (1 or 2 marks)
- gaps between energy levels are unique for a given element
6. Explain the bond angle in Sio4 (3)
- 4 regions of electron density around the central S atom
- electrons repel to get as far as away as possible/minimize repulsion
- bond angle 109....(I think i put that or did I put 120, hopefully not )
7. What is the other product of reforming (1)
- H2
8. Explain hess law ( 3 or 4)
- the enthalpy change of a reaction is the same independent of the route taken, providing the stat and finish conditions are the same
9. Describe similarities or difference between atomic absorption and emission spectra ( 2 or 4 )
- Difference: atomic emission is coloured lines on black background , absorption black lines on coloured backgrounds
- Similar: - line get closer at higher frequency for both, or I think I put both are line spectra...
10- explain why there is an increase in entropy in equation 2.1 and explain what entropy is (i think.. not sure this is from the mock or real paper)(3)
- entropy is measure of disorder. nor mumber of ways blah blah balh arrange particles
- more moles of gas on the right side so higher entropy/ gas has the highest entropy
11. write equation for cracking of decane to give 3 carbon alkene and something else (1 or 2)
C10H22 + C3H..........

well you can fix and add to it...

12. Why polystyrene cup was used and not a glass beaker?
- acts as an insulator to reduce heat transfer to surroundings
13. What other product produced in reforming?
- Hydrogen/Hydrogen gas
14. How can emission spectra be used to detect different elements?
- different elements have different energy gaps between levels so they will emit/absorb certain frequencies. Unique set of lines on the backgrounds.
15. Definition of structural isomers
- isomers with the same molecular formula but vary in their structural formula
16. Characteristics of ionics, giant covalent and simple covalent molecules
- ionics don't conduct electricity when solid, soluble
- simple molecule don't conduct electricity and insoluble