Question

Two students beging by mixing 5.0ml of a 3.1M solution of methyl orange and 5.0 ml of a 3.1 M solution of methyl red in an Erlenmyrer flask. How many drops of this mixture must be added to the top of the column so that 6.0 mmol of each dye is separated. 21drops = 1ml

Answer 1

Solution :-

6.0 mmol * 1 mol / 1000 mmol = 0.006 mol

Lets calculate the volume of each using its molarity and moles

Volume of methyl orange = moles / molairty

                                               = 0.006 mol / 3.1 mol per L

                                               = 0.00194 L

0.00194 L * 1000 ml / 1 L = 1.94 ml

Sinc ethe molarities of both is same

So the volume of the methyl red needed is also same that is 1.94 ml methyl red

So total volume of mixture needed = 1.94 ml +1.94 ml = 3.88 ml

Now lets convert volume from ml to drops

1 ml = 21 drop

3.88 ml = drops

3.88 ml * *21 drop / 1 ml = 81.5 drops