Question

8 A 0.005 cm thick coating of copper is deposited
on a plate of 0.5 m² total area. Calculate the
number of copper atoms deposited on the plate
(density of copper = 7.2 g cm , atomic
mass = 63.5).

Answer 1

Answer:

$1.71\times {{10}^{24}}$

Explanation:

$\text{Area of plate} = 0.5 {{m}^{2}} = 0.5 \times {{10}^{4}} c{{m}^{2}} \\Thickness of coating = 0.005 cm\\Volume of copper deposited = 0.5 \times {{10}^{4}} \times 0.005 = 25 c{{m}^{3}} \\Mass of copper deposited = 25 \times 7.2 = 180 g\\\text{Now, 63.5 g of copper contains atoms} = 6.022 \times {{10}^{23}} \\\therefore \text{180g of copper will contain atoms} = 6.022 \times {{10}^{23}} /63.5 \times 180 = 1.71\times {{10}^{24}}$

Answer 2

density=mass/volume

volume= area×thickness

these will help you calculate the mass

no. of atoms =given mass/ molecular mass×avogadro's number