How on Earth did you get Pb2O3? I divided by the mass they gave us by the atomic mass of the element which was given and got a ratio of 0.03 for lead and 0.045 for oxygen. So I simplified it down to Pb015.

Reply 64

electrahearts

OH MY GOD I just realised I missed out that balancing question!?!?!

Reply 65

ellefrancessa

Original post by ARiley1765

One of the worst papers I've seen I felt like it was so biased for some reason..

It all seemed to be on bonding! I know I've done terrible.. I didn't have time to answer half the questions. So glad I dropped triple and moved to double so biology and physics can pull my grade up hahah. Thank god for an A* in my ISA too!

Reply 66

Petroleum99

Original post by Mina_

Oh my god I can't believe I made that mistake. As a triple scientist aswell I'm disappointed. Thank you anyway :wink:

Reply 67

Emma_B1

Original post by Mina_

I did this apart from the last step- how many marks do you reckon that would be?

Reply 68

lewiswallis

can anyone give the main points that they will be looking for on the 6 marker?

Reply 69

RahulKOfficial

Original post by OpTic Crimbot

Btw Rahul what was ur answer for how solid lead is obtained from lead nitrate?

Evaporating and condensing

Reply 70

ellefrancessa

Original post by ARiley1765

One of the worst papers I've seen I felt like it was so biased for some reason..

Reply 71

Mina_

Original post by Emma_B1

I did this apart from the last step- how many marks do you reckon that would be?

Probably 3 out of 4, I wouldn't worry tbh

Reply 72

jammiedodger235

Original post by neil20143

I tried to make an unofficial mark scheme for this. Please be free to add things :smile:

1a. State one conclusion about the effect of temperature on the rate of reaction? (1 mark)
-An increase in temperature increases the rate of reaction

aii. One reason why? (1 mark)
-Because the volume of gas being produced at 40 degrees was more rapid than at 20 degrees.

a(iii). Average rate (1 mark)
-2 cm cubed per second (I think)

1 (b) two students should the student keep constant? (2 marks)
-Mass of Marble Chips
-Concentration of acid

b ii. Increasing the surface area affect the rate of reaction? (2 marks)

-Increases the rate of reaction
-As the particles are colliding more frequently (more successful collisions)

c. Why does a catalyst reduce costs?
-Because less energy is needed to start the reaction (as it has a lower activation energy)

(there may be alternatives)

2 (a). What could the student see? (1 mark)
-Copper being formed (brown) or zinc disappearing

2(b).Improves the investigation? (2 marks)
Improvement: Use a lid/ insulate the container
Reason: Prevents heat from being transferred to the surroundings/escaping.

2c (6 marker - will do later at some point)

3 (a). How does a metal conduct electricity? (4 marks)
-Delocalised electrons can move through the metal
-Transfer electrical charge
-Sea of moving electrons (structure)
-Lattice of positive ions (structure)

3(b). Describe the structure of an alloy is different to a metal (2 marks)
-Different elements with different sizes
-Distort layers in the mixture, preventing them from sliding over each other.
OR
-Irregular pattern of atoms.

3(c). Why is Nitinol used in braces? (1 mark)
-Hard/strong/corrosive-resistant/smart-alloy

3(c) (ii). Why are coins not made out of pure copper? (1 mark)
-Because it is too soft so will corrode

3 (c) (iii)). Aluminium Oxide

3 (c) (iv). How can the reaction produce two different products? (1 mark)
-Made using different reaction conditions / any specified reaction condition (e.g. pressure, temperature).
-Using different catalysts

3(d). Instrumental methods are used to detect impurities? (2 marks)
Any two from:
-They use very little samples.
-Accurate
-Sensitive
-Fast

4 (a). Why does Lithium have 7 as it's atomic number? (3 marks)
-3 protons
-4 neutrons
-3 + 4 = 7 which is its mass
-electrons have a very small mass.

4(b). Complete the sentences (2 marks)
-Grams
-Carbon-12

4(c). Isotope differences (3 marks)
-18-Oxygen had 2 more neutrons than 16-Oxygen
-Same number of protons
-Same number of electrons

5 (a). Name a soluble compound that contains silver
(1 mark)
-Silver Nitrate

5(a) ii Compound containing carbonate ions (1 mark)
-Potassium or Sodium Carbonate

5(b) (1 mark)
-(insoluble)Base

5(c) (i). State how lead nitrate can be obtained from lead nitrate oxide (1 mark)
-Crystalisation
-Evaporate and leave to dry.

5c(ii) (1 mark)

Pbo + 2HNO3 = PB(NO3) + H2O

5c (iii). number of atoms in the compound
-9

5(d). Empirical Formula (4 marks)
Pb2O3

6(a). Structure and bonding in sodium chloride (4 marks)
-Ionic Bonding
-Sodium atoms lose one electron to form positive ions
-Chloride ions gain one electron to form negative ions
-Opposites attract
-Giant ionic structure
-Cubic Lattice
-Electrostatic forces

Any of these should get the mark I think

6(b). Other products when brine is electrolysed (2 marks)
-Sodium Hydroxide
-Hydrogen

6(c). Ethical reason for not putting Iodine in food (1 mark)
-People may not want to have these extra Iodine amount (no choice)

6(d) (i). (2 marks)
-3 electrons lone pairs and one covalent bond

6(d) (ii). Why does Iodine have a low melting point (3 marks)
-Simple molecules
-Weak intermollecular forces
-Little energy needed to break them down

6(d) (iii). Why does iodine not conduct electricity? (2 marks)
-No overall charge so can't carry electrical charge

How come the answer for the empirical formula is Pb203? I got Pb02 and the majority of my year got that...

Reply 73

ladyrailly

Original post by electrahearts

OH MY GOD I just realised I missed out that balancing question!?!?!

It was only 1 mark, you'll be fine :smile:

Unless you mean the entire question and not just that specific part, in which case good luck with that

(also nice icon :biggrin:

)

Reply 74

varun1212

Are u able to do a similar one for the B2 test?

Reply 75

elllbabe

Original post by eza11

for 4b) I put moles and carbon-12?? Was it just me that didn't put grams?

I PUT MOLES TOOO!! :shakehand:

Reply 76

elllbabe

Original post by Petroleum99

Can anyone explain this empirical formula question, in so confused how you can get these figures ....

so basically people are a'l caught up in the 'you've gotta round to a whole number stage' like after you did mass divided by Mr for both then divide both outcomes by the smallest outcome, you've gotta round butt some people too thins as like literally round the numbers and others took this as scale them up until they're whole numbers
-hope this helps?

Reply 77

olivialilyholt

Original post by Palette

I wrote for the final question that although intermolecular forces in iodine are broken, the covalent bonds between two iodine atoms in an iodine molecule are not broken, meaning there are no delocalised electrons which can carry charge.

Is that valid?

that's exactly what I put, is it right?