8/18/2019 Things to remember for HSC chemistry
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Radioisotopes are used in industry, medicine and chemical
analysis. For
ONE of these elds, relate the use of a named radioisotope to
its
properties.
Cobalt-60 is used in medicine as a treatment for cancer. This
isotope decays by
beta emission and also releases gamma rays. Gamma radiation
kills cancer cells
because it is able to penetrate quite deeply into the body
tissue and is high
enough in energy to Destroy DN !ithin cells.
Cobalt-60 has a half-life or ".# years$ !hich is enough so that
it doesn%t need to
replacing often in the equipment$ but it short enough that the
source of the
radiation emits enough energy to be e&ecti'e in killing
cells.
Name ONE type of cell, other than the dry cell or lead-acid cell
that you
have studied. Evaluate it in comparison with either the dry cell
or lead-
acid cell, in terms of chemistry and the impact on society.
Include
relevant chemical equations in your answer.
• (ercury button cell compared to dry cell
• )oth ha'e a *inc anode but cathode in the mercury cell is C
and +g, !hile
in the dry cell it is C and (n,.
• )oth cells use a paste-type electrolyte$ ,+ in the mercury
cell and N+/Cl
in the dry cell
• The anode and cathode reactions are di&erent in each
cell(ercury node reaction 1n 2 ,+- 1n, 2 +, 2 e-Dry cell
Cathode reaction 1n 1n2 2 e-(ercury Cathode reaction +g, 2 +,
2 e- +g 2 ,+-Dry cell Cathode reaction N+/ 2 (n, 2 e-
(n,# 2
N+# 2 +,
• The dry cell is portable$ robust and east to story. 3or
these reasons they
allo! portability of torches and radios etc. +o!e'er$ the
mercury buttoncell has also had a large in4uence on society because
of its small si*e$ ithas allo!ed miniaturisation of technology such
as cameras.
• ,ne of the problems !ith the dry cell is that the 'oltage
drops during use
and it is therefore only useful for infrequent use$ for e5ample
torches. Themercury cell pro'ides a constant 'oltage o'er a long
period of time and isthus useful in hearing aids and !atches.
• )oth cells are relati'ely ine5pensi'e.
• The dry cell contains small about of *inc and slightly
acidic electrolyte
paste. These materials do not cause en'ironmental damage if dry
cells are
placed in household garbage. 3or mercury cells$ batteries should
berecycled as it is a hea'y metal to eliminate contamination to
theen'ironment.
yclohe!ene"cyclohe!ane
)r 2 +, +,) 2+)
+,) 2 C6+70 C6+70),+#he $i%erence &etween al'enes and
al'anes
lkanes and their corresponding alkenes are non-polar carbon
chain molecules
!ith !eak dispersion forces bet!een the molecules. 8hysical
properties such as
melting point and solubility are due to intermolecular forces.
These properties
are therefore similar.
