Download Yr12Ch27 - ChemistryVCE

Worked solutions to textbook questions
3
E3.
Why do you think it is necessary for the cells to be heated in order for them to
produce a voltage?
AE3.
The operation of the cells requires that sodium anode, sulfur cathode and electrolyte
are all in the molten state.
E4.
Provided the cells are discharged and charged every day, they remain at working
temperatures. Suggest the reason for this.
AE4.
During recharging, some of the electrical energy entering the cell is transformed into
chemical energy and some is transformed into heat. Heat energy is also released in the
cell when it discharges. This heat is sufficient to maintain the cell at working
temperatures if a discharge–recharge cycle is carried out every day.
E5.
According to the article, what are the disadvantages of electric vehicles compared
with petrol-driven vehicles at present?
AE5.
Electric vehicles do not generate carbon dioxide, which is a greenhouse gas.
E6.
Suggest the meaning of the term ‘energy density’. Why is energy density an important
factor in the construction of electric vehicles?
AE6.
The energy density of a cell is the energy available per unit mass of the cell. The
greater the energy density of a cell, the greater the range of the electric vehicle that is
using the cell.
E7.
‘Electric vehicles cause no pollution.’ Comment on the accuracy of this statement.
AE7.
While electric vehicles cause almost no pollution at the site at which they are used,
the electrical energy that is used to charge their batteries is produced by a series of
energy transformations that involve the production of pollutants. Typically, fossil
fuels will be burnt in order to produce the electrical energy.
E8.
Suppose your family operated an electric car that used lead–acid batteries. In what
ways would this affect your family’s lifestyle?
Heinemann Chemistry 2 (4th edition)
 Harcourt Education, a division of Pearson Australia Group Pty Ltd