Multiple Choice
What is the molarity of a NaCl solution if 3.16 moles of NaCl are dissolved in enough water to make 1 liter of solution?
6. Chemical Quantities & Aqueous Reactions
Molarity
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What is the molarity of a solution which contains 43.1 g of hexane (C6H14) dissolved in 250 mL of solution?
A
0.50 M
B
1.38 M
C
2.00 M
D
0.86 M
Verified step by step guidance1
Calculate the molar mass of hexane (C6H14) by adding the atomic masses of its constituent atoms: 6 carbon atoms and 14 hydrogen atoms. Use the periodic table to find the atomic masses: Carbon (C) is approximately 12.01 g/mol and Hydrogen (H) is approximately 1.01 g/mol.
Determine the number of moles of hexane by dividing the mass of hexane given (43.1 g) by its molar mass, which you calculated in the previous step. Use the formula: \( \text{moles of C}_6\text{H}_{14} = \frac{\text{mass of C}_6\text{H}_{14}}{\text{molar mass of C}_6\text{H}_{14}} \).
Convert the volume of the solution from milliliters to liters, since molarity is expressed in moles per liter. Use the conversion: 1 L = 1000 mL. Therefore, divide 250 mL by 1000 to get the volume in liters.
Calculate the molarity of the solution using the formula: \( \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{liters of solution}} \). Substitute the number of moles of hexane and the volume of the solution in liters into this formula.
Review the calculated molarity and compare it with the given options to determine which one matches your calculated value.
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