but i didn't miss out n anything that might prevent me from
getting the answer rite?
or could u just write the answer? Let me understand how its
being done like providing an example or something
What's the difference between volume and molar volume?
Garrick is doing a fine job trying to help you out.
>>> What's the difference between volume and molar
volume? <<<
It should be "sample volume" vs "molar volume". Molar volume =
volume of one mole (of the gas), just as molar mass = mass of one
mole (of the substance).
No of moles = sample mass / molar mass
No of moles = sample volume / molar volume
Both are obviously true, so use whichever formula is
applicable.
If you can't understand why they're true, let's use a Primary
school maths example.
If one chicken's mass is 1kg, and I have a sample of an
unknown number of chickens, and the sample mass is 10kg, how
many chickens do I have in the sample?
No of chickens = sample mass / chicken mass.
Similarly,
No of moles = sample mass / molar mass
Bet your school didn't teach you that way. They just told you to
memorize blindly, moles = mass / Mr, which doesn't make sense
to most students. No of moles = sample mass / molar mass, on the
other hand, makes perfect sense to everybody.
That's why if you (anyone from Sec 3 to JC2) have
difficulty understanding Chemistry taught in school, consider
coming for my tuition for your own sake.
As for your original problem, let x be the molarity of
HCl(aq).
(((50/1000)(x))/(2)) x (24000) = 500
Solve for x, and you've answered the question.
Explanation :
- the 50/1000 is volume in dm3
- the (x) is molarity
- hence (50/100)(x) = no of moles
- the / 2, is due to stoichiometry (ie. looking at the balanced
chemical equation).
- hence after dividing by 2, you obtain no of moles of the
gas
- the x 24000 is to obtain the sample volume of gas in cm3
- equate it to 500 since that's what's give in the question.
- solve for x, which is molarity (ie. concentration in mol/dm3)
of HCl(aq)