Calculate the number of moles of solute present in each of the following aqueous solutions: (a) \(600 \mathrm{~mL}\) of \(0.250 \mathrm{M} \mathrm{SrBr}_{2}\), (b) \(86.4 \mathrm{~g}\) of \(0.180 \mathrm{~m} \mathrm{KCl}\), (c) \(124.0 \mathrm{~g}\) of a solution that is \(6.45 \%\) glucose \(\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)\) by mass.

Short Answer

Expert verified
In summary, the number of moles of solute present in each solution is: (a) \(0.150 \mathrm{~mol}\) of SrBr2, (b) \(0.209 \mathrm{~mol}\) of KCl, and (c) \(0.0444 \mathrm{~mol}\) of glucose.

Step by step solution

01

Convert mL to L

To make calculations, we first need to convert the volume from milliliters (mL) to liters (L) using the conversion factor 1 L = 1000 mL: \(600 \mathrm{~mL} * \cfrac{1 \mathrm{~L}}{1000 \mathrm{~mL}} = 0.600 \mathrm{~L}\)
02

Calculate moles of solute

We know that molality (M) is equal to moles of solute per liter of solution. To calculate the number of moles, we will use the formula: Moles of solute = M x Volume of solution in L Moles of SrBr2 = \(0.250 \mathrm{~M} * 0.600 \mathrm{~L}\) Moles of SrBr2 = \(0.150 \mathrm{~mol}\) #(b) 86.4 g of 0.180 m KCl#
03

Calculate moles of solute from mass and molality

Given the molality (m) and mass of the solution, we can find the number of moles of solute (KCl) using the formula: Moles of solute = molality x (mass of solution / molecular weight of solute) Molecular weight of KCl = 39.1 (K) + 35.5 (Cl) = 74.6 g/mol Moles of KCl = \(0.180 \mathrm{~m} * \cfrac{86.4 \mathrm{~g}}{74.6 \mathrm{~g/mol}}\) Moles of KCl = \(0.209 \mathrm{~mol}\) #(c) 124.0 g of a solution that is 6.45% glucose (C6H12O6) by mass#
04

Calculate mass of solute

To find the mass of glucose in the solution, we will use the percentage given: Mass of glucose = (percentage of glucose / 100) x mass of solution Mass of glucose = \(\cfrac{6.45}{100} * 124.0 \mathrm{~g}\) Mass of glucose = \(8.00 \mathrm{~g}\)
05

Calculate moles of solute from mass

To find the number of moles of glucose, we will use the molecular weight of glucose and the mass of glucose in the solution: Molecular weight of glucose = 6(12.01) + 12(1.01) + 6(16.00) = 180.18 g/mol Moles of glucose = \(\cfrac{8.00 \mathrm{~g}}{180.18 \mathrm{~g/mol}}\) Moles of glucose = \(0.0444 \mathrm{~mol}\)

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