Question

How many moles of pentane are in 1.48x1021

Answer 1

multiply the number of each atom with its molecular mass. (see the periodic table)

5*12 + 12*1 = 72 gram per mole.

Or more accurately: 5*12.01078 + 12*1.007947 = 72.149264 g/mole

Answer 2

1.48 * 1021 number of molecules of pentane = 0.0002458 mol

Given data:

Number of molecules of pentane = 1.48 * 1021

Number of moles = ?

Solution:

1 mole = 6.02 × 1023 molecules.

If

1 molecule = 1/6.02 × 1023

So

1.48 × 1021 molecules = (1/6.02 × 1023) × 1.48 × 1021

= 2.458 × 10-3 mol

= 0.0002458 mol

So there are 0.000245 moles of pentane, if the number of molecules are 1.48 * 1021. Because 1 mole mole contain Avogadro's number of molecules.

Which is equal to 6.02 × 1023 molecules.