C1 2013

Question 1

1e In mass spectrometer, relative abundance of each isotope is proportional to current generated by isotope of detector
How is this current generated

Answer 1

Positive ions hit electric plate
Electrons transferred to positive ion
Smallest m/z value hit first

Question 2

3b State how two carbon atoms form a carbon-carbon bond in graphene

Answer 2

Shared pair of electrons

Question 3

5b Name type of bond formed in AlCl4- and explain how its formed

Answer 3

Coordinate bond
Electron pair on Cl- donated to Al

Question 4

4a Deduce the redox half equation for oxidation of sulfide ion in aq solution to form sulfate ion and H+ ions

Answer 4

S2- + 4H2O -> SO42- + 8e- + 8H+

Question 5

6b In bright sunlight, chlorine reacts with water to form oxygen as one of the products. Write an equation

Answer 5

Cl2 + 2H2O -> 4HCl + O2

Question 6

6c Explain why chlorine has a lower BP than bromine

Answer 6

Chlorine smaller than bromine
Forces between bromine stronger than forces between chlorine

Question 7

3cii Suggest why chloroethanoic acid is a stronger acid than ethanoic acid

Answer 7

Cl withdraws electrons
Weakens OH bond

Question 8

1b Explain meaning of ionic model

Answer 8

Perfect spherical
Point charges

Question 9

1c Suggest two properties of ions that influence the value of a lattice enthalpy calculated using perfect ionic model

Answer 9

Radius
Charge density

Question 10

4a By reference to the structure of and bonding of silicon dioxide suggest why it is insoluble in water

Answer 10

Macromolecular
Many covalent bonds between atoms
Water cannot break the covalent bonds

Question 11

4e Write a reaction between phosphorus oxide with NaOH

Answer 11

P4O10 + 12NaOH -> 4Na3PO4 + 6H2O

Question 12

5b Suggest why potassium chloride would not be a suitable salt for the salt bridge in this cell (Copper cell)

Answer 12

Cl- ions react with Cu2+

Question 13

5c In the external circuit of cell, electrons flow through the ammeter from right to left . Suggest why

Answer 13

Cu2+ in left hand electrode more concentrated
So reaction of Cu2+ with 2e- will occur at left hand

Question 14

5d Explain why current in external circuit of this cell falls to zero after cell has operated for some time

Answer 14

Cu2+ in each electrode same concentration

Question 15

5e Write an equation for the overall reaction that occurs when this lithium cell is being recharged

Answer 15

LiMnO2 -> Li + MnO2

Question 16

6d State 3 different features of TM that cause change in deltaE between ground to excited state

Answer 16

Variable oxidation states
Metal
Ligands