To solve this problem, let us say that:
x = volume of 1:2000 drug "i" solution
y = volume of 7% drug "i" solution
Assuming volume additive, then this forms:
x + y = 120 mL
<span>x = 120 – y ---> 1</span>
1:2000 also refers to 0.0005 concentrations and 7% also
refers to 0.07 concentrations. By doing a component balance:
0.0005 x + 0.07 y = 0.035 (120 mL)
0.0005 x + 0.07 y = 4.2
Substituting equation 1 into this derived equation to get an
equation in terms of y:
0.0005 (120 – y) + 0.07 y = 4.2
0.06 – 0.0005 y + 0.07 y = 4.2
0.0695 y = 4.14
y = 59.568 mL = 59.57 mL
From equation 1, x would be:
x = 120 - 59.57
x = 60.43 mL
Answers:
59.57 mL of 1:2000 drug "i" solution
60.43 mL <span>of 7% drug "i" solution</span>
