EjerciciosFyQ

Molarity from % (m/V) concentration (8303)

F_y_Q — 2024-09-08T03:42:27Z

Calculate the molarity of a sulfurous acid solution whose concentration is (m/V).

First, set a quantity of solution as the basis for calculation. Consider 100 mL of solution, which gives you 8 g of solute, , (these amounts are the “translation” of m/V).

The moles corresponding to that mass of solute are obtained from the molecular mass of the acid:

Calculate the moles equivalent to the mass of solute:

The molarity is the ratio between the moles of solute and the volume of the solution, expressed in liters, i.e., 0.1 L (because you considered 100 mL at the beginning):

Molar fraction and molality of a solution (8298)

F_y_Q — 2024-09-03T07:07:35Z

A solution contains by mass of HCl:

a) Calculate the molar fraction of HCl.

b) Calculate the molality of HCl in the solution.

You can fix an amount of 100 g of solution to solve the problem because, in those 100 g of solution, there will be 36 g of HCl (which is what the percentage means) and 64 g of water. Convert both quantities to moles:

a) Calculate the molar fraction:

b) Calculate the molality. This is defined as the ratio between the moles of solute and the mass of solvent, expressed in kilograms:

Mass of a volume of ethanol, expressed by pounds (4883)

F_y_Q — 2019-01-03T08:28:18Z

The density of ethanol is 0.79 g/mL. Calculate the mass, expressed in pounds, of 17.4 mL of ethanol, knowing that one pound is equal to 0.45 kg. Express the result using scientific notation.

We will solve this exercise in two steps. First, we will use the definition of density to calculate the mass of ethanol. Second, we will convert the units.

1. Calculate the mass of ethanol:

2. Convert the mass to pounds: