Question

What mass of gold (Au) contains the same number of atoms as 7.72g of aluminum (Al) ? in units of g

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Answer 1

55.16 gram of gold contain same number of atoms as 7.72 g Al contain.

Step-by-step explanation:

Given data:

Mass of Al = 7.72 g

Mass of gold contain same number of atoms as 7.72 g Al contain = ?

Solution:

First of all we will determine the atoms of Al in 7.72 g.

Number of moles = mass/ molar mass

Number of moles = 7.72 g / 27 g/mol

Number of moles = 0.286 mol

Number of atoms:

0.286 mol × 6.022 ×10²³ atoms / 1 mol

1.72 ×10²³ atoms

Now we determine the mass of gold that contain 1.72 ×10²³ atoms:

1 mol = 6.022 ×10²³ atoms

1.72 ×10²³ atoms× 1 mol / 6.022 ×10²³ atoms = 0.28 mol

Mass of gold = number of moles × molar mass

Mass of gold =0.28 mol × 197 g/mol

Mass of gold = 55.16 g