Chromium is an ultratrace metal in the human body. The typical concentration is 5.0 mg in 70.0 kg of body mass. This concentration can be expressed as ________

Question

Quizplus · Accepted Answer

To convert from mg/kg to ppm or ppb, we need to divide the mass of chromium (in mg) by the total mass of the body (in kg) and multiply by 1,000,000 for ppm or 1,000,000,000 for ppb.

For this problem, we have 5.0 mg of chromium in 70.0 kg of body mass:

5.0 mg / 70.0 kg = 0.0000714 mg/kg

To convert to ppm or ppb:

0.0000714 mg/kg x 1,000,000 = 0.0714 ppm or
0.0000714 mg/kg x 1,000,000,000 = 71.4 ppb

Therefore, the answer is A) 0.071 ppm or 71 ppb.

Chromium Is an Ultratrace Metal in the Human Body