Question

12. How many formula units are contained in 162.4 g of K Cro? - a. How many potassium ions? b. How many CrO 2. ions? C. How many atoms of all kinds?

Answer 1

12. Moles of K₂CrO₄ = mass of K₂CrO₄ / molar mass = 162.4 / 194.2 = 0.836 moles

Number of formula units = Avogadro number * moles = 6.022 * 10²³ * 0.836 = 5.03 * 10²³

a. Number of potassium ions = 2 * number of Formula units = 2 * 5.03 * 10²³ = 1.01 * 10²⁴

b. Number of CrO₄^2- = number of formula units = 5.03 * 10²³

c. Number of atoms per formula unit = 2 + 1 + 4 = 7

Number of atoms in this sample = 7 * number of formula units = 7 * 5.03 * 10²³ = 3.52 * 10²⁴