Question

If a copper acetate hydrate, Cu (C H O ) .zH O compound is found to contain 31.82% Copper, x232y2 59.14% acetate, and the remainder is water. What is the empirical formula of this compound

Answer 1

To find the empirical formula we assume that we have 100g of the compund, then we can convert every porcentual composition to mass.

Because the sub-indices of the formula represent a ratio of moles , it is necessary to convert the grams of each element in moles . The molar mass of each element is the conversion factor is needed. n represented the number of moles of each element

then n = m/ MW

nCu = 31.82 g * 63.546 g/mol = 0.50 mol

n Acetate = 59.14g / 59.04 g/mol = 1.001 mol

g water = 100-31.82-59.14 = 9.04 g

n Water = 9.04 g / 18 g/mol = 0.50 mol

chemical formulas are written with integers. Try to make them all integers dividing them by the smallest

0.50 / 0.50 = 1

1.001 / 0.50 = 2

0.50 / 0.50 = 1

Then we will have the empirical formula

Cu₁(CH₃O₂)₂.1H₂O ( the numbers of the acetate and the water are there because from the name of the compound er know how is there exact formula.)

Cu(CH₃O₂)₂.H₂O