OCR Chemistry F321 Exam. - [Next Tuesday[

Fe can have a charge of 2+ 0r 3+
You dont need to work out the chaarge, because you can see that there are 3 nitrogen atoms so there must be 3 nitrate ions, because there is one nitrogen ion in each

Describe the solubility of NaCl, Iodine and Diamond?

Describe the solubility of NaCl, Iodine and Diamond?

Explain why Mg has a higher boiling point than Na and also explain the trend in boiling point down group 1 metals?

Nacl is soluble in polar solvents such as water because the water molecules surround each ions and will weaken the lattice structure causing the bonds to break. Iodine is soluble in non polar solvents such as hexane as there are van der waals forces present between molecules and this formation of bond can be easily broken as they are weak.However diamond is insoulbe in both non polar and polar solvents because there are strong covalent bonds present between molecules and lots of energy is needed to break the bonds.

Yeah spot on. Basically it's because in ionic compounds the ions are attracted to the polar water molecules. In iodine the molecules are not attracted to the polar water molecules. In diamond it is insoluble as there are strong covalent bonds between the atoms which are strong

Describe and explain the solubility and pH of group 2 metals? -

As you go down the solubility increases and PH varies from 10-12

we do not need to know the explanation though not in syllabus
but i think its got to do with atomic radius cause it increases down the group

This is a pretty tricky question:

Suggest why Ba(OH)2 is used as an alkali, rather than using Mg(OH)2? (think about it, suggest questions means we are not meant to know the answer directly, use common sense and logic)

They could ask this today!

It's in the revision guide though - It popped up in one of the older past papers - you never know.

Basically solubility increases as the group is descended.
So more OH- ions are produced.
Hence being it more alkaline
Booooooooooooooooooom! 3 marks!

Describe and explain the solubility and pH of group 2 metals? -

because Ba(OH)2 is more alkaline than Mg due to if you go down the group alkalinity increases

Give an example with an aid of an equation to show 'disproportionation reaction'.

solubility of group 2 metals in water increases as you go down the group.

This means that the alkalinity of group 2 hydroxides in water increases because the concentration of OH- ions in the solution increases.

solubility of group 2 metals in water increases as you go down the group.

This means that the alkalinity of group 2 hydroxides in water increases because the concentration of OH- ions in the solution increases.