Question

A chemist samples a river's water to measure the amount of fertilizer runoff from the area farms. In a 0.0335 L sample, the chemist measures 258 μg of nitrate. Express the concentration of nitrate in parts per million (ppm) and parts per billion (ppb). Assume the density of the river water sample is 1.00 g/mL.

Answer 1

Answer:

7.7ppm

7700 ppb

Explanation:

• To calculate ppm, you need to convert your 258 μg to mg and your 0.0335L to kg using the density of the water:

$258microg*\frac{1mg}{1000microg} =0.258mg\\0.0335L*\frac{1000ml}{1L}*\frac{1g}{1ml}*\frac{1kg}{1000ml}=.0335kg$

• Now you use the ppm formula to obtain the answer:

$ppm (in mass) =\frac{solute(mg)}{solvent(kg)} =\frac{0.258mg}{0.0335kg}=7.7 ppm$

• To calculate ppb you need to consider that ppm is defined as $10^{6}$ and ppm as $10^{9}$, this means that ppm*1000=ppb

$ppb= 7.7ppb*1000= 7700ppb$

I hope you find this information useful! Good luck!