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25 February, 06:02

A substance is analyzed and found to contain 85.7% carbon and 14.3% hydrogen by weight. A gaseous sample of the substance is found to have a density of 1.87 g/L, and 1 mol of it occupies a volume of 22.4 L. Answer the following questions to determine two possible Lewis structures for molecules of the compound. What is the empirical formula of the compound?

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  1. 25 February, 06:13
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    The empirical formula of the compound is CH2

    Explanation:

    Step 1: Data given

    A substance contains 85.7 % carbon and 14.3 % hydrogen.

    The substance has a density of 1.87 g/L

    1 mol occupies 22.4 L

    Molar mass of carbon = 12 g/mol

    Molar mass of hydrogen = 1.01 g/mol

    Step 2: Calculate molar mass of the substance

    Since 1 mol occupies 22.4 L;

    1 mol of this substance = 1.87g/L * 22.4 = 41.888 grams

    This means the molar mass of the substance is 41.888 g/mol

    Step 3: Calculate mass of carbon:

    85.8 % is carbon

    this means 41.888 * 0.858 = 35.94 grams

    Step 4: Calculate moles of carbon

    moles C = mass C / Molar mass C

    Moles C = 35.94 grams / 12 g/mol

    Moles C = 2.995 moles

    Step 5: Calculate mass of hydrogen:

    14.3 % is hydrogen

    this means 41.888 * 0.143 = 5.99 grams

    Step 6 : Calculate moles of hydrogen

    Moles H = 5.99 grams / 1.01 g/mol

    Moles H = 5.93 moles

    Step 7: Calculate mol ratio

    Ratio C:H = 1:2

    The empirical formule = CH2

    Step 8: calculate molar formule

    Molar mass of empirical formule = 14.02 g/mol

    n = Molar mass of substance / molar mass of empirical formule

    n = 41.888 / 14.02 = 3

    This means we have to multiply the empirical formula by 3

    3 * (CH2) = C3H6

    C3H6 can be propene or cyclopropane
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