Question

For the Bradford Assay, the instructor will make a Bradford reagent dye by mixing 50 mL of 95% v/v ethanol with 100 mg of Coomasie Blue followed by the addition of 50mL of 85% v/v phosphoric acid. This entire mixture is then diluted to 1 liter with water. What is the final concentration of phosphoric acid?

Answer 1

95% V/V ethannol means 95 ml ethanol present in 100 ml solution

givent that; 50 mL of 95% v/v ethanol = 47.5 ml ethanol.

Here coomasie blue would be like an indicator only.

To calcualte the ml of phosphoric acid in its 50 will be = 85*50/100 = 42.5 ml

But the total volume = 100 ml

Thus conventration of phosphoric acid would be half (42.5 )of its original concentartion as the volume is doubled.

This would only be including the mixture of 50mL ethanol + 50mL phosphoric acid. To account for the dilution to 1L with the H2O.

N1V1 = N2V2

Here V2 = 1000 ml

42.5 * 100 mL = N2 *1000 ml

N2 = 4.25