Calculate number of grams in 1.15*10^21 molecules of P2O5

To go from molecules, we first need to convert to moles and then convert to grams.

To convert from molecules to moles, we need to divide by Avogadro's constant.

1.15*10^21 molecules * (1 mole/6.022*10^23 molecules) = 0.0019097 moles

To convert from moles to grams, we need to use the molar mass.

The molar mass of P₂O₅ is (2*30.98) + (5*16.00) = 141.96

You can find the molar mass using the periodic table.

0.0019097 moles * (141.96 grams/1 mole) = 0.2711 grams.

Since we have 3 significant digits in 1.15*10^21, that means our final answer is limited to 3 significant digits.

Your final answer is 0.271 grams.