Question

Calculate the atomic percent of tungsten in an alloy prepared with 56 grams of tungsten and 48 grams of aluminum. The atomic mass of tungsten is 183.85 g/mol and aluminum is 26.98 g/mol.

Answer 1

Given mass of aluminium , m_Al =48 g

Mass of tungsten , m_W = 56 g

Total mass , M = m_Al + m_W = 48+56 = 104 g

Number of moles of Al , n_Al = m_Al / atomic mass of Al

                                        = 48 g / 26.98 (g/mol)

                                        = 1.78 mol

Number of moles of W , n_W = m_W / atomic mass of W

                                        = 56 g / 183.85 (g/mol)

                                        = 0.304 mol

Total number of moles , N = n_Al + n_W = 1.78+0.304 = 2.084

So atomic percent of tungsten = (n_W / N )x100

                                            = (0.304/2.084)x100

                                            = 14.6 %