Question

Stainless steel is an alloy of iron containing 5 percent nickel and 0.175 percent chromium. How many atoms of nickel are present in a 84 g sample of this alloy?

Answer in units of atoms

Answer 1

First you need to work out what mass of 84g of stainless steel is nickel, and because there's 5% you can simply divide by 20, giving 4.2g

Answer 2

First you need to work out what mass of 84g of stainless steel is nickel, and because there's 5% you can simply divide by 20, giving 4.2g

For this you can use the equation
`Moles= (Mass)/(Mr)`

The mass, as was worked out previously, is 4.2g
The Mr, which is found on the periodic table, is 28

Moles =
`(4.2)/(28)` = 0.15mol

1mol = 6.023 x
`10^(23)` atoms

So, 0.15mol = 0.15 x 6.023 x
`10^(23)` = 9.0345 x
`10^(22)` atoms