The human body weighing 70 kg contains 42 g of magnesium. What is the number of magnesium atoms in the human body?

The number of atoms can be found by the formula N = n * N (a), where n is the amount of substance, N (a) is Avogadro’s number, which is 6.02 * 10 ^ 23 (1 / mol). The molar mass of magnesium is 24.305 g / mol. Let’s find the amount of magnesium substance by the formula n = m / M. So, n (Mg) = 42 / 24.305 = 1.728 mol. Now we find the number of magnesium atoms N = 1.728 * 6.02 * 10 ^ 23 = 10.4 * 10 ^ 23. Answer: the human body weighing 70 kg contains 10.4 * 10 ^ 23 magnesium atoms (10.4 multiplied by ten to the twenty-third power).