mass
'no magic to the mole'
amount
molar mass
concentration
solution volume
gas volume
molar gas volume
Avogadro
constant, L
number of
entities, N
Now try the following question.
X6. NAVIGATING FROM AMOUNT OF SUBSTANCE TO STOICHIOMETRY
It would be no exaggeration to suggest that the majority of teaching of stoichiometry - in the 14-17 year age range - ventures into the territory rather too early, before a sufficiently solid foundation has emerged that is capable of dealing with calculations involving just
a single substance, whether mass, gas, etc.
It should be understood that one who lacks competence in dealing with straightforward amount calculations involving a single substance - including their SI units - is hardly likely to meet with sustained success once introduced to stoichiometry, where the ideas must be applied to two or more chemical entities concurrently, while introducing the correct scaling factor, aka stoichiometric factor or amounts ratio.
The subject matter contained within AMOUNTofSUBSTANCE.com & STOICHIOMETRY.co.uk
is outlined below, with linked worked examples [WE] identified that should help to inform on the best starting point.
As a further pointer to where the reader might
begin on this pair of sites, the horizontal and vertical menus provide a clear indication of the layouts.
Generally, work left to right in the selection of topics from the horizontal menu; material is distributed corresponding to the order likely be encountered in most curricula.
Within any topic, work through the vertical menu as far down as is required, either by the curriculum or syllabus you follow, or as far as the level of challenge remains appropriate.
There is one caveat, however. To begin with, do not ignore the bottom of the SI drop down menu A13. (f) Q14. Manipulating products and A13 (g) Q.15. Manipulating quotients. These can be dealt with by being aware of A4. Physical Quantity - working definition & A5. Laws of Indices. This sets the scene for much of what follows.
Of course, several external factors will also need consideration in planning the best approach. Amongst these are likely to be: the existing competence levels of the student; the quality of instruction in their chemistry classes at school or college; the desired goals in terms of exam grade targets; any realistic university plans; and the time and resources available.
However, judicious use of these sites could save an individual the need for significant specialist intervention, not to mention the valuable time that might otherwise be wasted by ploughing through the plethora of sub-standard materials in circulation on these topics.
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