How many grams are in 3.14 moles of PI₃?

Explanation:

We want to convert from moles to grams, so we must use the molar mass.

The molar mass is the mass of 1 mole of a substance. It is the same as the atomic masses on the Periodic Table, but the units are grams per mole (g/mol) instead of atomic mass units (amu).

We are given the compound PI₃ or phosphorus triiodide. Look up the molar masses of the individual elements.

Note that there is a subscript of 3 after the I in the formula. This means there are 3 moles of iodine in 1 mole of the compound PI₃. We should multiply iodine's molar mass by 3, then add phosphorus's molar mass.

Use the molar mass as a ratio.

We want to convert 3.14 moles to grams, so we multiply by that value.

The units of moles of PI₃ cancel.

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated, that is the tens place.

The 2 in the ones place tells us to leave the 9.

3.14 moles of phosphorous triiodide is approximately equal to 1290 grams of phosphorus triodide.

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explanation:

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