# On the part, the surface area of which is 20 cm2, a layer of silver 1 μm thick is applied.

On the part, the surface area of which is 20 cm2, a layer of silver 1 μm thick is applied. How many silver atoms are contained in this layer

Data: S is the surface area of the layer (S = 20 cm2 = 2 * 10 ^ -3 m2); h – layer thickness (h = 1 μm = 10 ^ -6 m).

Const: ρAg – density of silver (ρAg = 10500 kg / m3); MAg is the molar mass of silver (MAg ≈ 0.108 kg / mol); Na is Avogadro’s number (Na = 6.022 * 10 ^ 23 mol-1).

To find out the number of silver atoms in the specified layer, consider the equality: Nx / Na = m / MAg, from where we express: Nx = Na * m / MAg = Na * ρAg * V / MAg = Na * ρAg * S * h / MAg.

Let’s perform the calculation: Nx = Na * ρAg * S * h / MAg = 6.022 * 10 ^ 23 * 10500 * 2 * 10 ^ -3 * 10 ^ -6 / 0.108 ≈ 1.17 * 10 ^ 20 atoms.

Answer: This layer contains 1.17 * 10 ^ 20 atoms.

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