Answer:
7.53*10²⁴ formula units are in 12.5 moles of calcium phosphate.
Step-by-step explanation:
The mole is defined as the amount of substance that contains as many entities (atoms, molecules, ions, electrons or other entities) as the number of atoms in 0.012 kg of pure carbon-12.
The Avogadro Number or Avogadro Constant is called the number of particles that constitute a substance (usually atoms or molecules) and that can be found in the amount of one mole of that substance. So Avogadro's number represents the amount of atoms in 0.012 kg of carbon 12. Its value is 6.023 * 10²³ particles per mole. Avogadro's number applies to any substance.
The formula unit is the smallest repetitive unit of a substance, a molecule for non-ionic substances. Then one mole of a compound contains Avogadro's number of formula units (molecules or ions) thereof.
The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them. That is, what is intended with it is to find the fourth term of a proportion knowing the other three. Remember that proportionality is a constant relationship or ratio between different magnitudes.
If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:
a ⇒ b
c ⇒ x
Then
The rule of three applies in this case as follows: if one mole of calcium phosphate contains 6,023 * 10²³ (Avogadro's number) formula units, 12.5 moles of the compound how many formula units will it contain?
formula units≅7.53*10²⁴
Then, 7.53*10²⁴ formula units are in 12.5 moles of calcium phosphate.