EjerciciosFyQ

Relationship between molarity and normality (8380)

F_y_Q — 2025-01-27T04:52:56Z

Calculate the normality of the following solutions: a) (2 M) b) (0.4 M) c) (3 M) d) (1 M) e) (2 M)

Normality is defined as the number of equivalents of solute in one liter of solution. The mass of an equivalent is the molecular mass divided by the number of "H" or "OH" groups in the acid or base considered. This means that the relationship between normality and molarity is that normality is equal to molarity multiplied by the number of "H" or "OH" groups in the species.

a)

b)

c)

d)

e) (because it is a salt with a 1:1 stoichiometry between its ions).

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:

Raoult's law and vapor pressure (8282)

F_y_Q — 2024-08-09T03:43:44Z

Calculate the vapor pressure at of a solution containing 150 grams of glucose dissolved in 140 grams of ethyl alcohol. The vapor pressure of ethyl alcohol at is 43 mm Hg.

Glucose is and has a molecular mass of 180 g/mol. Ethyl alcohol is and has a molecular mass of 46 g/mol. Using this data, calculate the moles of each substance and determine the mole fraction of alcohol in the mixture.

The mole fraction of alcohol is:

Now calculate the vapor pressure using Raoult's law:

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:

Solutions: Percentage by mass (1931)

F_y_Q — 2012-11-10T07:55:39Z

Make a solution by mixing 22 g of sugar and 240 mL of milk. Determine the percentage by mass of this solution. How much sugar is needed to prepare 500 g of solution with the same concentration?

Average density of milk is .

The mass of milk used for the mixture is:

The total mass of the solution is:

The mass percentage is:

The obtained result indicates that you need 8.17 g of sugar to prepare 100 g of solution: