8462/1H June 2022

3  ​​ ​​​​ This​​ question​​ is​​ about​​ different​​ forms​​ of​​ carbon

Figure​​ 5​​ represents​​ the​​ structure​​ of​​ diamond

Figure​​ 5

3-1 Describe​​ the​​ structure​​ and​​ bonding​​ of​​ diamond.

[3​​ marks]

ANSWER

It​​ has a giant covalent structure with all the carbons joined by covalent bonds in a giant lattice. This can be thought of as a continuous network of atoms linked by covalent bonds. All the carbons joined by covalent bonds in a giant lattice. Each carbon atom​​ is covalently bonded to four other carbon atoms

3-2 ​​ Explain​​ why​​ diamond​​ has​​ a​​ very​​ high​​ melting​​ point. ​​ 

[3​​ marks]

ANSWER

Covalent bonds are strong and many covalent bonds must be broken so a lot of energy is required hence high melting point.

Figure​​ 6​​ represents​​ the​​ molecule​​ C70

Figure​​ 6

3-3  ​​​​ What​​ is​​ the​​ name​​ of​​ this​​ type​​ of​​ molecule?

[1​​ mark]

ANSWER

Fullerene

 

3-4 ​​ Molecules​​ such​​ as​​ C70​​ can​​ be​​ used​​ in​​ medicine​​ to​​ move​​ drugs​​ around​​ the​​ body.

Suggest one reason why the C70 molecule is suitable for​​ this use.​​ 

[1 mark]

ANSWER

For delivery of drugs throughout or specific parts of the body and/or cells – the drugs are often carried inside the hollow center of the fullerene molecule.

3-5 ​​ Calculate​​ the​​ number​​ of​​ C70​​ molecules​​ that​​ can​​ be​​ made​​ from​​ one​​ mole​​ of carbon atoms.

The Avogadro constant = 6.02 × 1023 per mole

     [3 marks]

ANSWER

moles of C70molecules=170

=0.0142857

molecules=0.0142857×6.02×1023

=8.6×1021