c. How many milliliters of 10% povidone-iodine (Betadine ) solution would be
needed to make 4 liters of a 1:2000 Betadine solution?
USE THESE STEPS:
Step 1: V C = V1 C1
Step 2: (X) (10%) = (4 L) ( 1 )
Step 3: (a) Change 4 liters to milliliters
Change 10% to a ratio by placing the 10 over 100.
(X) (10) = (4000 ml) ( 1 )
NOTE: At this point, use the rule of mathematics that states that if both sides of the
equal sign are multiplied by the same number, the sides will still be equal. The
easiest way to simplify an equation having ratios on both sides of the equal
sign is to multiply both sides of the equal sign by the larger denominator. In
this case the larger denominator is 2000; therefore, multiply both sides by
(X) (20,000) = (4000 ml) (2000)
*200 X = 4000 ml
X = 20 ml
*When zeros trail whole numbers on both sides of the equal sign, an equal number of
zeros may be cancelled on each side without changing the value of the equation.
d. How many milliliters of a 1:200 silver nitrate solution would be needed to
make 2000 ml of a 1:4000 solution?
V C = V1 C1
= (2000 ml) ( 1 )
(X) (4000) = (2000 ml) (4000)
20 X = 2000 ml
X = 100 ml