[mac227]

If X + 2Y   XY₂  and we have a 10 mL solution of 1 molar X that we mix with a 2 molar solution of Y, how many ml of Y solution would be required for a complete reaction? (so no X or Y are left over)

it should be 20 mL correct??

[opti384]

So you will have 0.01 mols of X. How many mols of Y will you need by judging from the equation?

[RickyC]

The answer is 10mL of Y.

                                       X+2Y→XY₂

You have 10mL of 1M X therefore the number of moles of X is given by:

Number of moles= (Volume x Molarity)/1000 = (10mL x 1M)/1000 = 1/100 = 0.01 moles

And you have twice as many moles of Y as X, therefore number of moles of Y = 0.02.

Also you have 2M Y so,

0.02 = (Volume x 2M)/1000  → 20 = Volume x 2 → Volume = 10mL.    

This is assuming of course that all of X and Y are used up.