To determine the number of atoms in a given mass of a substance, you need to use Avogadro's number and the molar mass of the element.
The molar mass of calcium (Ca) is approximately 40.08 grams per mole (g/mol), which means that one mole of calcium atoms weighs 40.08 grams.
To calculate the number of moles of calcium in 153 grams, you can use the formula:
Number of moles = Mass / Molar mass
Number of moles of calcium = 153 g / 40.08 g/mol ≈ 3.818 moles
Now, using Avogadro's number, which is approximately 6.022 x 10^23 atoms/mol, you can calculate the number of atoms:
Number of atoms = Number of moles x Avogadro's number
Number of atoms = 3.818 moles x (6.022 x 10^23 atoms/mol) ≈ 2.298 x 10^24 atoms
Therefore, there are approximately 2.298 x 10^24 atoms of calcium in 153 grams of calcium.