Q19.
Water can be found as ice, water and steam.
(a) The following diagram shows the arrangement of some of the water molecules in a crystal of ice.
With reference to the structure shown above give one reason why ice is less dense than water.
(1)
(b) Water and methane have similar relative molecular masses and both contain the element hydrogen.
The table below gives some information about water and methane.
(i) State the strongest type of intermolecular force holding the water molecules together in the ice crystal.
(1)
(ii) State the strongest type of intermolecular force in methane.
(1)
(iii) Give one reason why the melting point of ice is higher than the melting point of methane.
(1)
(c) A molecule of H2O can react with an H+ ion to form an H3O+ ion.
(i) Draw and name the shape of the H3O+ ion. Include any lone pairs of electrons.
(2)
(ii) Suggest a value for the bond angle in the H3O+ ion.
(1)
(iii) Identify one molecule with the same number of atoms, the same number of electrons and the same shape as the H3O+ ion.
(1)
(d) Water can also form the hydroxide ion.
State the number of lone pairs of electrons in the hydroxide ion.
(1)
(Total 9 marks)