Chemistry A Level Help out Ruhab III

Help with this plz
@Pigster @Deggs_14
Would u do 0.019/25 *250
to dilute factor it and then what? and the answer should be in moles

Help with this plz
@Pigster @Deggs_14
Would u do 0.0191/25 *250
to dilute factor it and then what? and the answer should be in moles

I don’t know about this question, sorry

Help with this plz
@Pigster @Deggs_14
Would u do 0.0191/25 *250
to dilute factor it and then what? and the answer should be in moles

2.23 g contains 0.019076 mol of the NH4VO3. This is dissolved into 250 cm3 of solution.

25 cm3 of this is used in the titration. This 25 cm3 must contain only a portion of the entire NH4VO3.

Your sum, 0.0191/25 *250 suggests that there is 0.191 mol of NH4VO3 in the sample! I should know you've made a mistake there.

(Original post by Ruhab Dabeer)Oh I have no bloody clue how to do the questions in Chem help 3 Pigster Deggs_14

A crucial part of the Q is not shown in your attached pictures (although I know the Q well and could, if I needed to, just find it).

The way I suggest you think about it is as follows:

2 mol of dichromate is found to oxidise 3 mol of substance X with an oxidation number of +2 to a higher (unknown) oxidation number. (I hope you can see how this is essentially the same as your Q, only with different numbers).

Constructing the half-equation for dichromate, you can work out that 1 mol of dichromate will steal 6 mol of e- when it causes oxidation.

Therefore 2 mol of dichromate will need to steal 12 mol of e-.

Now those 12 mol of e- are going to be stolen off 3 mol off X. Well, that's 4 e- off each X, which is an increase of oxidation number of 4, i.e. X goes to an oxidation number of +6.

SOooo am I right or wrong??

Right or wrong about what?

I have just noticed a mistake in my typing

I meant "You should know you've made a mistake there."

about the answer?

About what answer? I might be missing something here, but I can't see anywhere that you've put an answer (except for 0.0191, which is correct).

Would u do 0.0191/25 *250
to dilute factor it and then what? and the answer should be in moles

this ^

Like I said, the 250 cm3 solution contains 0.0191 mol.

25 cm3 of that solution is removed and Ruhab Dabeer suggests that the 25 cm3 now contains 0.191 mol, i.e. ten times the number of mol of the solution it is taken from.

That's either wrong or there is crazy magic taking place.

Now those 12 mol of e- are going to be stolen off 3 mol off X. [i ]Well, that's 4 e- off each X,

how do we decide if its 4 e- off each X?

If I steal 12 dozen sweets off 3 dozen people, on average, how many sweets does each person lose?

If I steal 12 dozen sweets off 3 dozen people, on average, how many sweets does each person lose?

Was my answer right!