Multiple Choice
What is the molarity of a solution which contains 43.1 g of hexane (C6H14) dissolved in 250 mL of solution?
6. Chemical Quantities & Aqueous Reactions
Molarity
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What volume of solution is prepared when 25.0 g of ethanol (C₂H₅OH) is added to enough water to make a 0.750 M ethanol solution? (Molar mass of ethanol = 46.08 g/mol)
A
0.250 L
B
0.500 L
C
0.725 L
D
1.000 L
Verified step by step guidance1
First, calculate the number of moles of ethanol using its mass and molar mass. Use the formula: \( \text{moles of ethanol} = \frac{\text{mass of ethanol}}{\text{molar mass of ethanol}} \). Substitute the given values: \( \text{mass of ethanol} = 25.0 \text{ g} \) and \( \text{molar mass of ethanol} = 46.08 \text{ g/mol} \).
Next, use the definition of molarity to find the volume of the solution. Molarity (M) is defined as the number of moles of solute per liter of solution: \( M = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \). Rearrange this formula to solve for the volume of solution: \( \text{volume of solution} = \frac{\text{moles of solute}}{M} \).
Substitute the calculated moles of ethanol and the given molarity (0.750 M) into the rearranged formula to find the volume of the solution: \( \text{volume of solution} = \frac{\text{moles of ethanol}}{0.750 \text{ M}} \).
Ensure the units are consistent when performing the calculation. The volume will be in liters since molarity is expressed in moles per liter.
Finally, compare the calculated volume with the provided options to determine which one matches the calculated result.
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