Ab asked in Science & MathematicsChemistry · 1 month ago

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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  • Ash
    Lv 7
    1 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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