Taking 25mL from a 500mL solution that has been DILUTED from 50mL?!?! (1 Viewer)

[Prawnchip]

Hey guys

Say you need to find the conc. of C6H8O7 in a drink. To do this, you dilute 50mL of the drink to 500mL then you take out 25mL of this diluted solution and titrate it standardised NaOH.

You know the volume of NaOH used and you know the concentration so you can find moles of NaOH used. From here, you can find the moles of C6H8O7. Since you know the moles of C6H8O7 and the volume (25mL) then you can find the concentration.

But my question is, how do you find the original concentration from here? Obviously you need to times the answer but 10 since its a 1 in 10 dilution but the concentration worked out is for 25mL right? and this 25mL comes from 500mL so do you do something with this??? like multiply by 20 or sth idk

Thanks so muchh :'))))

 

[iStudent]

Multiply by 10. The conc. In 25 ml sample is equivalent to the conc of diluted 500 ml sample (removing 25 ml from the 500 ml sample doesn't change the concentration) Thus to get original conc you multiply by 500/50 = 10.

 

[Prawnchip]

Multiply by 10. The conc. In 25 ml sample is equivalent to the conc of diluted 500 ml sample (removing 25 ml from the 500 ml sample doesn't change the concentration) Thus to get original conc you multiply by 500/50 = 10.

OHH omg ty so much xx

 

[faisalabdul16]

Multiply by 10. The conc. In 25 ml sample is equivalent to the conc of diluted 500 ml sample (removing 25 ml from the 500 ml sample doesn't change the concentration) Thus to get original conc you multiply by 500/50 = 10.

Yeap exactly!