2 different hydrocarbons , X and Y, each contains the same
percentage by mass of carbon. It follows that they have the
same
1 empirical formula (not possible since they are
different hydrocarbons so the number of H atoms would be different.
When reduced to simplest form, ratio is different)
2 molecular formula (also not possible due to above cited
reason)
3 relative molecular mass
4 structural formula (definite no, no. of H atoms
different)
I''m left with option 3. Am I right? Still am not convinced by
my answer.
The following observations were made with nitrate of metal X
i) a deposit of metal X formed when an Fe nail was placed in a
solution of the nitrate
ii) a brown gas is formed when the solid nitrate was
heated strongly (possible identities of gas: NO2 or
Br2)
iii) when copper was placed into aq. nitrate, no change was
observed
based on the above info. what is the position of X in the
reactivity series?
1 above Na
2 Between Na and Fe
3 between Fe and Cu
4 below Cu
Because I'm not very sure what hint is (ii) trying to give, the
best guess would have to be C.... ah, well.
thanks all
Oh yea, there's one more question to clarify.
What is it that the relative molecular mass of the organic
compound decrease in the fermentation of glucose into ethanol? (one
of the MCQ questions)
3 would be wrong since same Mr means same number of H and C
which would make it similar to 2 and 4. Do note that empirical and
molecular formulas are not the same so 1 and 2 are not the
same.
I would choose 1 as the answer since % is just used to calculate
empirical formula and 2 compounds having the same empirical formula
can have different molecular formulas.
Eg. C2H4 and C4H8 will have the same empirical formula but
different molecular formula, molecular mass and structural
formula.
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C should be correct for this question. Nitrates will give off NO2
when heated strongly i believe. (long time never did such
expts)
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As fermentation occus, the glucose is broken down to ethanol and
there are byproducts being formed such as CO2 if i didn't recall my
biological chemistry wrongly so the losses of CO2 causes the
molecular mass of the compound to decrease as the compound now has
less 1 C and 2 O.