A student has a bottle labeled 0.750% albumin solution. The bottle contains exactly 5.00 mL. How much water must the student add to make the concentration of...

Question

...of albumin become 0.125%?

Please solve the equation step by step including any conversions you may have to do and the formula for this equation 

Answer 1

(5 ml)(0.75%) = (x ml)(0.125%)

x = 30 ml so one would need to add 25 ml to the original 5 ml to obtain a final volume of 30 ml.

 

Another approach:

0.750% means 0.75 g/100 ml (assuming weight volume percentage)

0.750 g/100 ml x 5 ml = 0.0375 g albumin in the 5 ml bottle

To make this 0.125%, you want to dilute it to 0.125g/100 ml, but you have only 0.0375 g in total.

0.0375 g/x ml = 0.125 g/100 ml would be the ratio or proportion you would set up.

Solving for x, you obtain x = 30 ml which is the final volume.  So, 25 ml needs to be added to the original 5 ml