Question

Привет. Химия! Выручайте! Пособие Хомченко. Само задание: Для определение массовой доли оксида кальция в смеси его с карбонатом кальция образец смеси массой 0,8 г обработали избытком раствора соляной кислоты. В результате выделился газ объемом 112 мл( норм.условия). Определите массовую долю оксида кальция в смеси

Answer 1

CaO+2HCl=CaCl2+H2O

CaCO3+2HCl=CaCl2+H2O+CO2

v(CO2)=V(CO2)/Vm=0.112/22.4=0.005моль

v(CO2)=v(CaCO3)=0.005 моль

m(CaCO3)=v(CaCO3)*M(CaCO3)=0.005*100=0.5г

m(CaO)=m(смеси)-m(CaCO3)=0.8-0.5=0.3г

w(CaO)=m(CaO)/m(смеси)=0,3/0,8=0,375 или 37,5%

Ответ: w(CaO)=37,5%

 

 

Answer 2

Determining the Mass Fraction of Calcium Oxide in a Mixture

To determine the mass fraction of calcium oxide (CaO) in a mixture with calcium carbonate (CaCO3), we can use the reaction between calcium carbonate and hydrochloric acid (HCl). The reaction can be represented as follows:

CaCO3 + 2HCl → CaCl2 + H2O + CO2

From the balanced equation, we can see that 1 mole of calcium carbonate reacts with 2 moles of hydrochloric acid to produce 1 mole of calcium chloride, 1 mole of water, and 1 mole of carbon dioxide.

Given that the sample of the mixture has a mass of 0.8 g and that excess hydrochloric acid was used, we can determine the mass of calcium oxide produced by considering the stoichiometry of the reaction.

To calculate the mass of calcium oxide, we need to determine the number of moles of carbon dioxide produced. We can use the ideal gas law to relate the volume of carbon dioxide to the number of moles:

PV = nRT

Where: - P is the pressure of the gas (at normal conditions, 1 atm) - V is the volume of the gas (112 mL or 0.112 L) - n is the number of moles of the gas (which we want to find) - R is the ideal gas constant (0.0821 L·atm/(mol·K)) - T is the temperature of the gas (at normal conditions, 273 K)

By rearranging the equation, we can solve for n:

n = PV / RT

Substituting the given values, we can calculate the number of moles of carbon dioxide produced.

Next, we can use the stoichiometry of the reaction to relate the number of moles of carbon dioxide to the number of moles of calcium oxide. From the balanced equation, we know that 1 mole of calcium carbonate produces 1 mole of carbon dioxide and 1 mole of calcium oxide.

Finally, we can calculate the mass of calcium oxide produced by multiplying the number of moles of calcium oxide by its molar mass.

Let's calculate the mass fraction of calcium oxide in the mixture using the given information.

Calculation:

1. Calculate the number of moles of carbon dioxide produced: - P = 1 atm - V = 0.112 L - R = 0.0821 L·atm/(mol·K) - T = 273 K

   n_CO2 = PV / RT
   

2. Calculate the number of moles of calcium oxide: - From the balanced equation, we know that 1 mole of calcium carbonate produces 1 mole of carbon dioxide and 1 mole of calcium oxide.

   n_CaO = n_CO2
   

3. Calculate the mass of calcium oxide: - The molar mass of calcium oxide (CaO) is 56.08 g/mol.

   mass_CaO = n_CaO * molar mass_CaO
   

4. Calculate the mass fraction of calcium oxide: - The mass fraction is the mass of calcium oxide divided by the mass of the mixture.

   mass fraction_CaO = mass_CaO / mass_mixture
   

Let's perform the calculations.

Solution:

1. Calculate the number of moles of carbon dioxide produced: - P = 1 atm - V = 0.112 L - R = 0.0821 L·atm/(mol·K) - T = 273 K

   n_CO2 = (1 atm * 0.112 L) / (0.0821 L·atm/(mol·K) * 273 K)
   

The number of moles of carbon dioxide produced is approximately 0.005 mol.

2. Calculate the number of moles of calcium oxide: - From the balanced equation, we know that 1 mole of calcium carbonate produces 1 mole of carbon dioxide and 1 mole of calcium oxide.

   n_CaO = n_CO2
   

The number of moles of calcium oxide is approximately 0.005 mol.

3. Calculate the mass of calcium oxide: - The molar mass of calcium oxide (CaO) is 56.08 g/mol.

   mass_CaO = 0.005 mol * 56.08 g/mol
   

The mass of calcium oxide produced is approximately 0.2804 g.

4. Calculate the mass fraction of calcium oxide: - The mass fraction is the mass of calcium oxide divided by the mass of the mixture.

   mass fraction_CaO = 0.2804 g / 0.8 g
   

The mass fraction of calcium oxide in the mixture is approximately 0.3505 or 35.05%.

Therefore, the mass fraction of calcium oxide in the mixture is approximately 35.05%.

Please note that the calculations provided are based on the information given in the question.