Thank you for the warm welcome, hiphop2009, owner of the
SgForum's Homework Forum! Your Homework Forum has helped many a
grateful Sg student preparing for the exams.
I'll take this opportunity as Mod to share the joy of
Chemistry. It is my hope that more students at the secondary school
levels and 'O' levels will enjoy Chemistry enough to opt to take it
up at the 'A' levels, in the Polytechnics, or beyond that in the
Universities.
The following is one of my favourite classic questions that
I personally designed and wrote, to challenge my students and
to illustrate how Chemistry is really lots of fun :
A bubble of gas (initial diameter 1.585 cm; mass 2.0973 x 10^-2
g) that contains twice as much oxygen as it does carbon dioxide,
emerges from a photosynthesizing aquatic plant (there’s a
plesiosaur reptile aka “Loch Ness monster” right next to the plant,
btw) at the bottom of a lake, where the temperature is really cold
and the pressure is 6.4 times greater than at the lake’s surface;
and the bubble rises until it reaches the surface of the lake
(which happens to be at sea level, and at that moment is equivalent
to room temperature), and bursts “pop!”.
i) Calculate the diameter (in cm) of the bubble just before it
bursts.
ii) Calculate the body temperature (in °C) of the plesiosaur at the
time the bubble emerges.
iii) Calculate the diameter (in cm) of this gas bubble if it were
instantaneously teleported to the core of the sun (600 thousand
times hotter than room temperature and 340,000 million times more
crushing than Earth’s sea level atmospheric pressure), and assuming
it somehow remains miraculously intact (although in reality, you
probably wouldn't want to be hanging around an environment so
hot and crushing that atomic nuclei are constantly and forcibly
being fused together).
After attempting the above, check your Answers :
(i) 3.0 cm.
(ii) 8 deg C.
(iii) 0.0159 cm.
Everyone Loves Chemistry!
