Question

How much water (in mL) would need to be added to a 7 gram sample of iron to create a 7 ppb solution?

A)100000
B)1090
C)1000000
D)1000000000

Answer 1

To make a 7 ppb solution of iron, one needs 999,999,993 mL of water, which approximates to 1 billion mL or option D) 1000000000.

Step-by-step explanation:

To create a 7 ppb (parts per billion) solution of iron, we need to determine the volume of water that must contain 7 grams of iron to achieve that concentration. By definition, 7 ppb means there are 7 grams of iron per billion grams of solution.

Since 1 gram of water is approximately equal to 1 mL of water at room temperature, we can use the conversion of 1 g = 1 mL. Therefore, for a 7 ppb solution, we need 7 grams of iron to be mixed with enough water to make a total solution weight of one billion grams (or one billion milliliters since the density of water is approximately 1 g/mL).

To find the amount of water needed, we subtract the mass of the iron from the total mass of the solution:

1,000,000,000 g (total solution) - 7 g (iron) = 999,999,993 g (water needed)

So, the correct answer is 999,999,993 mL of water, which is closest to choice D) 1000000000.