Chapter 4: Problem 58

Calculate the molarity of each of the following solutions: (a) \(6.57 \mathrm{~g}\) of methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right)\) in \(1.50 \times\) \(10^{2} \mathrm{~mL}\) of solution, (b) \(10.4 \mathrm{~g}\) of calcium chloride \(\left(\mathrm{CaCl}_{2}\right)\) in \(2.20 \times 10^{2} \mathrm{~mL}\) of solution, (c) \(7.82 \mathrm{~g}\) of naphthalene \(\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)\) in \(85.2 \mathrm{~mL}\) of benzene solution.

Short Answer

Expert verified

Therefore, the molarities of the solutions are: (a) 0.137 M, (b) 0.043 M, and (c) 0.716 M.

Step by step solution

Calculate the Moles of the Solute

First, convert the weight of each solute to moles using its molar mass (which can be obtained from the Periodic Table of Elements). The molar mass of methanol \(CH_{3}OH\) is 32.04 g/mol, calcium chloride \(CaCl_{2}\) is 110.98 g/mol, and naphthalene \(C_{10}H_{8}\) is 128.17 g/mol. Thus, the amount of moles of each solute is: (a) \(6.57 g / 32.04 g/mol = 0.205 mol\), (b) \(10.4 g / 110.98 g/mol = 0.094 mol\), and (c) \(7.82 g / 128.17 g/mol = 0.061 mol\).

Calculate the Volume in Liters

Next, convert the volume of each solution to liters. Note that 1 mL = 0.001 L. Therefore, the volume of each solution in liters is: (a) \(1.50 \times 10^{2} mL = 1.50 L\), (b) \(2.20 \times 10^{2} mL = 2.20 L\), and (c) \(85.2 mL = 0.0852 L\).