# CHEMISTRY HELP!!!?

How many moles of C3H8 (molar mass 44.09 g/mol) are represented by 5.31 g of this compound? Give your answer correctly to three significant digits.

How many C atoms are present in the sample of C3H8 with mass 5.31 g? Avogadro’s number is 6.022 × 1023. Enter your answer using scientific notation and to three significant digits.

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- AshLv 71 month ago
moles of C3H8 = mass of C3H8 / molar mass of C3H8

= (5.31 g)/(44.09 g/mol)

= 0.120 mol

There are 3 'C' atoms in a molecule of C3H8

so moles of C = 3x 0.120 = 0.360 mol

number of C toms = moles of C atoms x Avogadro's number

= (0.360 mol)x (6.022 x 10²³ atoms/mol)

= 2.17 x 10²³

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