Question

If you have an initial absorbance (concentration) of 0.4 and you want 8mL of final chloroplast solution with a final absorbance (concentration) of 0.1, how many mL of the 0.4 solution needs to be part of the final 8mL of solution? HINT: Use this equation - CiVi = CfVf

Answer 1

We need to apply dilution law, which is based on the mass conservation principle

initial mass = final mass

this apply for moles as weel ( if there is no reaction, which is the case )

mol of A initially = mol of A finally

or, for this case

moles of A in stock = moles of A in diluted solution

Recall that

mol of A = Molarity of A * Volume of A

then

moles of A in stock = moles of A in diluted solution

Molarity of A in stock * Volume of A in stock = Molarity of A in diluted solution* Volume of A in diluted solution

Now, substitute known data

A1V1 = A2V2

0.4*V1 = 0.1*8

V1 = 0.1/0.4*8 = 2 mL required