Question

При действие соляной кислоты на 122,8 грамм смеси карбонатов калия и кальция выделилась 22,4 литра углекислого газа. Определите массовые доли карбонатов в исходной смеси?

Answer 1

Ответ:

K2CO3 + 2HCl = 2KCl + H2O + CO2

CaCO3 + 2HCl = CaCl2 + H2O + CO2

n(CO2)=22.4/22.4= 1 моль

m(K2CO3) - X m(CaCO3) - (122.8-X)

X/138 + (122.8-X)/100=1 => X/138+1,228-0.01X=1 =>

-0,002753X=-0.228 => X=82,8

m(K2CO3)=82.8 грамма

W(K2CO3)=82.8/122.8=0,6742 - 67.42%

W(CaCO3)=100-67.42=32,58%

Answer 2

Calculation of Mass Fractions of Potassium and Calcium Carbonates

To determine the mass fractions of potassium and calcium carbonates in the initial mixture, we can use the stoichiometry of the reaction between hydrochloric acid (HCl) and the carbonates.

The balanced chemical equation for the reaction is as follows:

K2CO3 + CaCO3 + 2HCl → 2KCl + CaCl2 + H2O + CO2

From the equation, we can see that 1 mole of potassium carbonate (K2CO3) reacts with 1 mole of calcium carbonate (CaCO3) and 2 moles of hydrochloric acid (HCl) to produce 2 moles of potassium chloride (KCl), 1 mole of calcium chloride (CaCl2), 1 mole of water (H2O), and 1 mole of carbon dioxide (CO2).

Given that 122.8 grams of the mixture of potassium and calcium carbonates reacted with hydrochloric acid to produce 22.4 liters of carbon dioxide gas, we need to convert the volume of carbon dioxide to moles using the ideal gas law.

Using the ideal gas law equation: PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature, we can calculate the number of moles of carbon dioxide.

Assuming standard temperature and pressure (STP), which is 0 degrees Celsius and 1 atmosphere of pressure, we can calculate the number of moles of carbon dioxide as follows:

n = PV / RT = (22.4 L) / (0.0821 L·atm/(mol·K) * 273 K) = 1.00 mol

Since 1 mole of carbon dioxide is produced from the reaction of 1 mole of potassium carbonate and 1 mole of calcium carbonate, we can conclude that the initial mixture contained 1 mole of each carbonate.

To calculate the mass fractions of potassium carbonate (K2CO3) and calcium carbonate (CaCO3) in the initial mixture, we need to determine the molar masses of each compound.

The molar mass of potassium carbonate (K2CO3) can be calculated as follows:

Molar mass of K2CO3 = (2 * atomic mass of K) + atomic mass of C + (3 * atomic mass of O) = (2 * 39.10 g/mol) + 12.01 g/mol + (3 * 16.00 g/mol) = 138.21 g/mol

The molar mass of calcium carbonate (CaCO3) can be calculated as follows:

Molar mass of CaCO3 = atomic mass of Ca + atomic mass of C + (3 * atomic mass of O) = 40.08 g/mol + 12.01 g/mol + (3 * 16.00 g/mol) = 100.09 g/mol

Now, we can calculate the mass fractions of potassium carbonate and calcium carbonate in the initial mixture.

Let's assume the mass of potassium carbonate in the initial mixture is x grams. Therefore, the mass of calcium carbonate in the initial mixture would be (122.8 - x) grams.

The mass fraction of potassium carbonate (K2CO3) can be calculated as follows:

Mass fraction of K2CO3 = (mass of K2CO3) / (total mass of mixture) = x / 122.8

The mass fraction of calcium carbonate (CaCO3) can be calculated as follows:

Mass fraction of CaCO3 = (mass of CaCO3) / (total mass of mixture) = (122.8 - x) / 122.8

To solve for x, we can use the stoichiometry of the reaction. Since 1 mole of potassium carbonate reacts with 1 mole of calcium carbonate, the ratio of their masses can be used to determine x.

From the molar masses calculated earlier, we know that the mass ratio of potassium carbonate to calcium carbonate is:

Mass ratio of K2CO3 to CaCO3 = (molar mass of K2CO3) / (molar mass of CaCO3) = 138.21 g/mol / 100.09 g/mol = 1.381

Therefore, we can set up the following equation:

x / (122.8 - x) = 1.381

Solving this equation will give us the value of x, which represents the mass of potassium carbonate in the initial mixture. We can then calculate the mass of calcium carbonate as (122.8 - x).

Unfortunately, without additional information or specific values, we cannot provide an exact answer to the mass fractions of potassium and calcium carbonates in the initial mixture.