Try this Mole Concepts O Level Chemistry questions:
Question:
If 2g of hydrogen gas contains x molecules, how many molecules would 2g of nitrogen gas contain?A) x
B) 7x
C) x/14
D) x/28
Show me the working briefly on how you derive your answer. This way we can determine your concepts for this chapter.
ps: Leave your suggested answers in the “Comments” section below.
Rgds
Sean
hello, who are you? you left me a comment yesterday. anyway, you have a good heart to make this blog
. it helps O level students a lot. especially me. haha.
Reply
Well, i will try to answer this question.
2g of hydrogen gas = 2H2 = 4 = x
2g of nitrogen gas = 2N2 = 2×14 = 28
28/4=7
since 4=x, therefore,
nitrogen gas is 7x.
well, i dont know whether i did correctly or not though. please correct me if i’m wrong.
Reply
hmm… i try…
2g of hydrogen gas = 1 mol =x
2g of nitrogen gas = 2g/28g =1/14 mol
therefore, if 1 mol is x, then 1/14 mol = x/14 #
correct?
Reply
No. of moles of H2 = 2/2 = 1mol
No. of molecules of H2 = (1)(6*10^23) = 6*10^23
let 6*10^23 = x
No. of moles of N2 = 2/28 = (1/14)mol
No. of molecules = (1/14)(6*10^23) = x/14
hence, answer is C.
is it right?
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hmm i guess it’s x/14 too.
i thought its about molar mass.
so what’s the right answer actually ?????
Reply
Halo Students,
Well Done to all for at least even bother to try it out and sharing with fellow students.
Yup. Answer is indeed C, x/14.
linwood-you can refer to the 2 answers given by robobooga and lijun. Do let me know if you need clarification on it. Stay positive and cheerful as you prepare…
=)
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