Monel metal is a corrosion-resistant copper-nickel alloy used in the electronics

Question

Monel metal is a corrosion-resistant copper-nickel alloy used in the electronics industry. A particular alloy with a density of 8.80 g/cm3 and containing 0.083 % Si by mass is used to make a rectangular plate that is 15.0 cm long, 12.5 cm wide, and 3.50 mm thick and has a 2.50-cm-diameter hole drilled through its center such that the height of the hole is 3.50 mm . The silicon in the plate is a mixture of naturally occurring isotopes. One of the those isotopes is silicon-30, which has an atomic mass of 29.97376 amu. The percent natural abundance, which refers to the atoms of a specific isotope, of silicon-30 is 3.10%.

A. The answer is 63.9 and I got it CORRECT

B. How many silicon-30 atoms are found in this plate? PLEASE HELP

Explanation / Answer

Find silicon-30 atoms in the plate

Mass = D*V

V plate = 63.9 cm3

mass = 8.8*63.9 = 562.32 g of metal

note that

0.083% is Si

mass of Si = 562.32 * 0.083/100 = 0.4667256 g of Si

1 mol of Si = 29.97377017 g

then

mol = mass/MW = 0.4667256 /29.97377017 = 0.0155711 mol of Si

1 mol = 6.022*10^23

0.0155711 mol --> (0.0155711)(6.022*10^23) = 9.376*10^21 atoms

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