Question

задача по химии(9 класс)Для полного растворения оксида марганца(4) MnO2 массой 43,5 г потребовалась соляная кислота объемом 260 см3.Какова массовая доля HCl в соляной кислоте,если ее плотность 1,13 г/см3? Определите массовую долю образовавшейся соли в конечном растворе

Answer 1

MnO2 + 4HCl = MnCl2 + Cl2 + 2H2O

n(MnO2) = m(MnO2)/M(MnO2) = 43,5/87 = 0,5 моль

По уравнению n(HCl)  = 4*n(MnO2) = 4*0,5 = 2 моль

m(HCl) = n(HCl)*M(HCl) = 2*36,5 = 73 г

 

m(p-paHCl) = V(p-paHCl)*po = 263*1,13 = 297,19 г

 

W(HCl) = m(HCl)/m(p-paHCl) = 73/297,19 = 0,25 или 25%

 

n(MnCl2) = n(MnO2) = 0,5 моль

m(MnCl2) = n(MnCl2)*M(MnCl2) = 0,5*126 = 63 г.

W(MnCl2) = m(MnCl2)/m(p-pa)

m(p-pa) = m(p-paHCl) + m(MnO2) - m(Cl2) (хлор выделяется в виде газа, поэтому он покидает раствор)

По уравнению n(Cl2) = m(MnO2) = 0,5 моль

m(Cl2) = n(Cl2)*M(Cl2) = 0,5*71 = 35,5 г

m(p-pa) = 297,19 + 43,5 - 35,5 = 305,19 г

W(MnCl2) = 63/305,19 = 0,21 или 21%.

Answer 2

Task Analysis

To solve this chemistry problem, we need to determine the mass fraction of HCl in the hydrochloric acid and the mass fraction of the resulting salt in the final solution.

Mass Fraction of HCl in Hydrochloric Acid

The mass fraction of HCl in hydrochloric acid can be calculated using the given mass of manganese dioxide and the volume of hydrochloric acid required.

Mass Fraction of Resulting Salt in Final Solution

The mass fraction of the resulting salt in the final solution can be calculated using the mass of manganese dioxide and the mass of the resulting salt.

Let's proceed with the calculations.

Mass Fraction of HCl in Hydrochloric Acid

The mass of manganese dioxide (MnO2) is 43.5 g, and the volume of hydrochloric acid is 260 cm^3. We can use this information to calculate the mass fraction of HCl in the hydrochloric acid.

The density of hydrochloric acid is given as 1.13 g/cm^3.

The mass fraction of HCl in hydrochloric acid can be calculated using the formula: Mass fraction = (mass of HCl / total mass of solution) * 100%

Using the given information, we can calculate the mass fraction of HCl in the hydrochloric acid.

Mass Fraction of Resulting Salt in Final Solution

The mass of the resulting salt in the final solution can be calculated using the mass of manganese dioxide and the mass of the resulting salt.

We can use the balanced chemical equation for the reaction between manganese dioxide and hydrochloric acid to determine the mass of the resulting salt.

Let's proceed with the calculations and provide the answers.