Mass of Aspirin in a tablet

Question

In a lab determining the mass of acetylsalicylic acid in an aspirin tablet, I'm having trouble with the dilution part of my calculation.

 

An unknown solution was made by placing an aspirin tablet in 10mL of a 1M NaOH solution and heating. This solution was then transferred to a 250mL flask and filled to the mark with DI water. Then, 5.0mL of this aspirin tablet solution was transferred to a 100mL flask and diluted to the mark with a 0.02M Iron(III) solution. This solution was labelled "unknown"

 

The concentration of the unknown solution determined using spectrophotometric analysis, then Beer-Lambert Law was 3.16 x 10^-4 mol/L

 

I've done the calculation like this, but I'm not confident that I've done the dilution part correctly:

3.16 x 10^-4mol/L x 0.100L/0.005L x 0.250L x 180.16g x 1000mg = 285mg

 

 

thanks!

 

Answer 1

You're correct.