>>> One often knows that a triple bond between 2
carbon atoms is NOT 3 times as strong as a single
bond between 2 carbon atoms. However I do not understand the
explanation behind this. <<<
To properly, fully, correctly understand this, you need to get
into 'A' level concepts. It has to do with atomic radii,
electronegativity, bond polarity, electron repulsion
between lone pairs, etc.
Here's a further hint : even the (seemingly)
same single bond between two atoms of the same element
(eg. C-C) has different bond strengths/enthalpies in different
molecules (different microenvironments), let alone single bonds
between different element atoms in different molecules (eg. C-H vs
H-H vs O-H, etc)!
So obviously, since two different single bonds (eg. C-H vs H-H)
already have different strengths, you cannot possibly have a
simplified direct relationship between ALL triple bonds to ALL
single bonds (because different single bonds already have
different strengths among themselves!).
Here's a sneak preview into the Data Booklet used at 'A' levels
(which is the average bond energies across a range of commonly
encountered molecules) :
>>> Another question is regarding stirring. Take for
example a reaction between NaOH and HCl acid. When NaOH is added to
acid, we would often be required to stir the mixture. May I know
what are other purposes of stirring beside making the NaOH solution
be even distributed throughout mixture? If I do not remember
wrongly, stirring does help hasten the reaction time, doesn't it?
(Not sure about this, Haha) <<<
One reason why stirring hastens reaction time, is because
the OH-(aq) becomes more evenly distributed by your stirring (and
hence more available by virtue of allowed closer
proximity for reaction with the more evenly spread out
or ubiquitous H+ from the acid), in addition to
(obviously) increasing kinetic energy of
all particles (solute, solvent, reactant, products) by
your stirring. You gotta make links and see connections
between everything (eg. between Chemistry and Biology, between
Chemistry and Physics, between Science, Philosophy, Religion, etc).
Then the universe will actually begin to make sense.
Also, don't forget the even distribution of heat is also a
reason for stirring (particularly when heating is involved.
Besides, almost all reactions are at least slightly endothermic or
exothermic.)
>>> A physics-chemistry question: does an insulated
container prevent solution inside it from absorbing and giving off
heat energy to surroundings? <<<
For your answer (spoonfeeding's no fun), here's another glimpse
into 'A' level Chemistry (and Physics) :
http://en.wikipedia.org/wiki/Calorimeter
One often knows that a triple bond between 2 carbon atoms
is NOT 3 times as strong as a single bond between
2 carbon atoms. However I do not understand the explanation
behind this.
Another question is regarding stirring. Take for example a
reaction between NaOH and HCl acid. When NaOH is added to acid, we
would often be required to stir the mixture. May I know what are
other purposes of stirring beside making the NaOH solution be even
distributed throughout mixture? If I do not remember wrongly,
stirring does help hasten the reaction time, doesn't it? (Not sure
about this, Haha)
A physics-chemistry question: does an insulated container
prevent solution inside it from absorbing and giving off heat
energy to surroundings?
Very simple questions which I need some addressing.
Not forgetting, thanks.
