You would need 2.5ml CHCl3 in CH3OH to a final solution volume of 100ml
Which is: 2.5*5 = 12.5ml CHCl3 in CH3OH to a final solution volume of 500ml.
Be careful: mixing liquids very often means that the volumes are not additive: It is therefore not correct to say: add 12.5ml CHCl3 to 487.5ml CH3OH.
