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What is the percent by mass of glucose in a solution containing 0.15 moles of glucose dissolved...

Question:

What is the percent by mass of glucose in a solution containing {eq}0.15 {/eq} moles of glucose dissolved in {eq}410\ g {/eq} acetic acid? The molar mass of glucose is {eq}180\ g/mol {/eq}.

Converting Between Mass and Number of Moles

The amount of a chemical species may be specified using colloquial units including grams, kilograms (for solids), and liters, cubic centimeters (for liquids and gases). Alternatively, we may use a unit peculiar to chemistry - the mole. The link between the mole and the mass in grams is the molar mass of the element or the compound. The unit of molar mass is g/mol. For elements it may be obtained directly from the periodic table, but for compounds, it has to be computed from the molecular formulae.

Answer and Explanation:

We have 0.15 moles of solute (glucose), whose molar mass is 180 g/mol. How many grams are these? We multiply:

{eq}0.15 \ mol \times 180 \ g/mol = 27 \ g {/eq}.

The mass of the solvent (acetic acid) is 410 g. Hence, the total mass of the solution is:

{eq}410 \ g + 27 \ g = 437 \ g {/eq}.

The percentage by mass of glucose is obtained as:

{eq}\displaystyle \frac{27 \ g}{437 \ g} \times 100\% = 6.18\% {/eq}


Learn more about this topic:

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What is Molar Mass? - Definition, Formula & Examples

from General Studies Science: Help & Review

Chapter 27 / Lesson 24
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