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| Understanding the concepts
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| 1.a.
| Avogadro's number is the number of units that are present in 1 mol of substance. This number is 6.022 X 1023. The lightest atom is boron and the heaviest atom is gold.
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| b.
| The molar mass of a substance is the mass (in grams) of 1 mol of the substance. The molar mass can be used to convert the mass of a substance to moles of substance and vice versa (from moles of substance to mass of substance). |
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| 3.
| Glucose and acetic acid are both 40.00% C, 6.714% H, and 53.29% O by mass. Both the glucose formula (C6H12O6) and the acetic acid formula (C2H4O2) have the same smallest whole number ratio of atoms present, i.e., both have CH2O as the empirical formula. |
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| 4.a.
| When a compound is analyzed for composition, the most common type of data collected is the mass percent of elements present. From mass percent data, only the smallest whole number ratio of atoms can be determined. Hence, only empirical formulas can be determined from mass percent data. |
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| c.
| To determine the molecular formula, we must know the molar mass of the compound. By comparing the molar mass of the compound to the empirical formula mass, we can determine the whole number required to convert the empirical formula to the molecular formula.
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