Question

300 g FeCrNi alloy is 70 wt% Fe, 20 wt% Cr, and 10 wt% Ni.

Calculate the following

a. The mass of Fe in the sample.

b. The mole fraction of Fe.

c.The density of the alloy in g/cm3 and kg/m3

Answer 1

a) The mass of Fe is calculated:

m Fe = 300 g alloy * (70 g Fe / 100 g alloy) = 210 g

b) The moles of each element are calculated:

n Fe = g / MM = 70 / 55.85 = 1.25

n Cr = 20/52 = 0.38

n Ni = 10 / 58.7 = 0.17

You have the mole fraction of Faith:

X Fe = n Fe / n total = 1.25 / (1.25 + 0.38 + 0.17) = 0.69

c) Density is calculated:

D = total m / mi / di

D = 100 / (70 / 7.87) + (20 / 7.19) + (10 / 8.90) = 7.81 g / cm3

D! = 7.81 g / cm3 * (1 Kg / 1000 g) * (100 cm / 1 m) ^ 3 = 7810 Kg / m3

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