Question

Question #2eec6

Answer 1

`"0.36292 moles"`

Explanation:

For starters, you already know that `1` mole of rubidium has a mass of `"85.4678 g"` because rubidium has a molar mass of `"85.4678 g mol"^(-1)`.

So if you know the mass of `1` mole of rubidium, you can use it as a conversion factor to figure out the number of moles needed to have `"31.018 g"`.

`31.018 color(red)(cancel(color(black)("g"))) * "1 mole Rb"/(85.4678color(red)(cancel(color(black)("g")))) = color(darkgreen)(ul(color(black)("0.36292 moles Rb")))`

The answer must be rounded to five sig figs, the number of sig figs you have for the mass of rubidium.