Siberian Tanker

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Siberian Tanker

by ssmiles08 » Sun Jun 07, 2009 4:09 pm
A tanker departing from Siberian port of Nakhodka is filled at 80 prcent of capacity with heavy Siberian blend of oil, which is oil and sulphur solution with 30 percent sulphur content. 30 percent of the tanker's capacity is off loaded in murmansk to be processed into heating oil for local customers. Then, the tanker proceeds to a North Sea terminal where it is loaded to capacity with Brent blend of oil, in which sulphur is negligible. Aproximately, what percent of the resulting oil solution in the tanker is sulphur?

(A). 15%
(B). 18.75 %
(C). 21%
(D). 24%
(E). 30%
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by Claret » Sun Jun 07, 2009 4:40 pm
( A ) 15 %

what's the ans?

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by Neo2000 » Sun Jun 07, 2009 4:41 pm
If my understanding is correct "30% of the tanker's capacity" implies that after the unloading, only 50% of the tank is full.

in which case this Q now boils down ( :D) to
Equal parts of 70% oil solution is mixed with a 100% oil solution.
[spoiler]Final oil concentration will therefore = (70+100)/2 = 85% which means S conc = 15%[/spoiler]
Last edited by Neo2000 on Sun Jun 07, 2009 4:41 pm, edited 1 time in total.

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by ssmiles08 » Sun Jun 07, 2009 4:41 pm
OA is (A)

Can you explain further please?

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by ssmiles08 » Sun Jun 07, 2009 4:48 pm
Neo2000 wrote:If my understanding is correct "30% of the tanker's capacity" implies that after the unloading, only 50% of the tank is full.

in which case this Q now boils down ( :D) to
Equal parts of 70% oil solution is mixed with a 100% oil solution.
[spoiler]Final oil concentration will therefore = (70+100)/2 = 85% which means S conc = 15%[/spoiler]

OOH gotcha! thanks! I got lost with the 30% of tanker's capacity

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by Claret » Sun Jun 07, 2009 4:50 pm
yes the catch in the Q is exactly what neo2000 has highlighted

after unloading , oil that remains is 50% of total capacity of the tank

say tank capacity is T

after unloading

oil = .5 * .7 *T = .35T
sulphur = .5*.3*T = .15T

amt of brent oil added = .5T

therefore % of sulphur in the resultant mixture = .15T/(.5+.35+.15)T = 15%