Task

Natural chlorine consists of the isotopes ³⁵Cl and ³⁷Cl; its mean relative atomic mass is 35.45 (take the isotopic masses equal to the mass numbers). A 22.18 g sample of calcium chloride made from natural chlorine is also given (Ar(Ca) = 40). 1) Calculate the atomic fractions (%) of the isotopes in natural chlorine. 2) Calculate the fractions (%) of Cl₂ molecules with relative molecular masses 70, 72 and 74 and check the result via the mean molar mass of Cl₂. 3) Find the number of ³⁷Cl atoms in the calcium chloride sample and the total number of neutrons in their nuclei (NA = 6.02·10²³ mol⁻¹). For every part, show the method (reaction equations, formulas, reasoning) and all calculations step by step.