xdesigninc

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I got this question from ACE THE DAT (too many mistakes in my opinion)
Help me out with this one I keep getting 3.2g ( not even one of the answers)

The ans: is C (has no explanation at all)

In a chemical reaction involving 6 atoms of oxygen and 3 atoms of phosphorus, how many grams of oxygen are required by 3.1 g of phosphorus?

A. 12.0 g O

B. 2.5 g O

C. 8.0 g O

D. 3.5 g O

E. 4.0 g O

Thanks
 

KiTmAn

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i would pick C..well the answer i got was 6.2. becuase the mole ratio is 1:2 of P:O (P3O6) so...3.1:6.2..thas y but i m not really sure if im reasoning is rite..please someone correct me...
 
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Cher*

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Oct 23, 2006
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I was planning to get ace the dat, but I heard that it's not very ideal. so I was just wondering if you guys found ace the dat helpful in preparation for the DAT? :confused:
 

doc toothache

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The reaction between phosphorus and oxygen is as follows:

P4 + 5O2 = P4O10
Since you have 3.1 g of phosphorus=0.1Moles

In order to react with 0.5 moles of oxygen, you will need 8.0 g of oxygen.
 

HenryH

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The reaction between phosphorus and oxygen is as follows:

P4 + 5O2 = P4O10
Since you have 3.1 g of phosphorus=0.1Moles

In order to react with 0.5 moles of oxygen, you will need 8.0 g of oxygen.
I thought the original problem was stated to have 6 atoms of Oxygen and 3 atoms of Phosphorous? :confused:
 

doc toothache

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Let's see... 3.1 grams of phosphorus and 3 atoms. I would say we are looking at a super giant P atom.
 

HenryH

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Oh, do you take the 3.1 g of Phosphorous and the 3 atoms given initially and find the number of atoms?
 

doc toothache

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The first part of the problems may have been written in error or it was included as a decoy. In any case, it is not relevant to solving the problem, since the amount of phosphorus is given. It is expected, however, that the problem solver know that phosphorus reacts with oxygen to give phosphorus pentoxide. The more difficult part is knowing that P2O5 is the empirical formula, while P4O10 is the molecular formula.
 
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