Question

QUESTION 10 Write the chemical formula for the compound formed from Cr3+ and SO42- Path: pWords:0 3 points QUESTION 11 What is the mass of one mole of copper (II) sulfate pentahydrate, CuSO4*SH2O 3 points QUESTION 12 A compound containing carbon and hydrogen contains 4.75 g of carbon and 0.80 g of hydrogen. The molar mass of the compound is about 28 g/mol What is the empirical formula of the compound? What is the molecular formula of the compound? ССС 23
help #10-12

Answer 1

10.

The charge of the ions in a compound is balanced.

A charge balanced compound can form when 2 Cr³⁺ combine with 3 SO₄^2-.

Chemical formula: Cr₂(SO₄)₃

11.

Mass of 1 mol of copper(II) sulfate pentahydrate = molar mass of copper(II) sulfate pentahydrate = 249.68 g

12.

Mass of C in the compound = 4.75 g

Molar mass of C = 12 g/mol

Moles of C in the compound = 4.75 g/12 g/mol = 0.396 mol

Mass of H in the compound = 0.80 g

Molar mass of H = 1 g/mol

Moles of H in the compound = 0.80 g/1 g/mol = 0.80 mol

Mole ratio of C : H = 0.396 : 0.80

                              = 0.5 : 1.0

                              = 1 : 2

Hence, the empirical formula of the compound = CH₂

Let us say that the molecular formula of the compound = (CH₂)_n             (where, n is an integer)

Molar mass of the compound from the empirical formula = n x (12 + 2) g/mol

                                                                                          = 14n g/mol

Now,

14n g/mol = 28 g/mol

or, 14n = 28

or, n = 2

Hence, the molecular formula of the compound = (CH₂)₂ = C₂H₄