Question

How many moles are in 550.0 g of lead(II) sulfate?

Answer 1

`"1.814 moles PbSO"_4`

Explanation:

You can go from moles of a given substance to grams or vice versa by using the molar mass of said substance.

The molar mass tells you the mass of `1` mole of a given substance

`"molar mass" = "mass in grams"/"1 mole of substance"`

In your case, lead(II) sulfate, `"PbSO"_4`, has a molar mass of `"303.2626 g mol"^(-1)`, which means that every mole of lead(II) sulfate has a mass of `"303.2626 g"`.

To convert from grams to moles, set up the molar mass as a conversion factor with the mass of `1` mole as the denominator

`"1 mole PbSO"_4/"303.2626 g"`

You will have

`550.0 color(red)(cancel(color(black)("g"))) * "1 mole PbSO"_4/(303.2626color(red)(cancel(color(black)("g")))) = color(darkgreen)(ul(color(black)("1.814 moles PbSO"_4)))`

The answer is rounded to four sig figs.