Question

You have 57.0ml of a 0.400M stock solution that must be diluted to 0.100M. Assume volumes are addictive. How much water should you add?

Answer 1

use \(M_1V_1=M_2V_2\)

then add water necessary to achieved the req'd volume.

Answer 2

What?

Answer 3

use the dilution formula (above), once you find what the volume should be, adjust it by adding the amount of water necessary.

Answer 4

does that give you 228?

Answer 5

units?

Answer 6

288M

Answer 7

228m

Answer 8

they're asking for the amount of water you should add. it should be in units of volume.

Answer 9

so 0.288

Answer 10

it's the correct value, given you use the appropriate units.

Answer 11

Right

Answer 12

but note that that is the TOTAL volume and you already have 57 mL

Answer 13

Ok so... it's 0.228M

Answer 14

M is in units of concentration.

Answer 15

M = mol/L

Answer 16

Ok i'm getting confused.

Answer 17

you need units of volume.

\(M_1V_1=M_2V_2 \rightarrow 0.057L*0.4 M=V_2*0.1 M\)

\(V_2=\dfrac{0.057L*0.4 M}{0.1 M}=0.288 L\)

but you already have 57 mL.

0.288 L - 0.057 L =your answer

Answer 18

Oh... I have to subtract it from 0.0057

Answer 19

you subtract 0.057 from it, yes. because you're adding water to it to reach that volume

Answer 20

Makes sense now. Thank you.