Calculate the number of moles of solute present in each of the following solutions?

1. Calculate the number of moles of solute present in 270 mL of 1.40 M HNO3(aq).

2. Calculate the number of moles of solute present in 55.0 mg of an aqueous solution that is 1.65 m NaCl. Assume that for dilute aqueous solutions, the mass of the solvent is the mass of solution.

3. Calculate the number of moles of solute present in 75.0 g of an aqueous solution that is 1.40 % sucrose (C12H22O11) by mass.

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  • 4 weeks ago
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    a) Ans. concentration = no. of moles of solute * 1000/ vol. in m;

    no. of moles of solute = concentration * vol / 1000 = 1.4 * 270 / 1000 = 0.378 = 0.378 mol.

    b)

    molality = 1.65

    molality = moles of solute / mass of solvent in kg

    1.65 = moles of solute / 5.5 x 10^-5 kg

    moles of solute = 9.075 x 10^-5

    c)

    mass of sucrose = 75 x 1.4 / 100 = 1.05g

    moles = 1.05 / 342 = 3.07 x 10^-3

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