Question

13. К раствору гидроксида натрия массой 200 г, содержащему 10% основного вещества, прибавили раствор хлорида меди (II) в достаточном количестве. Рассчитайте массу образовавшегося осадка.

Answer 1

M(H2SO4)в исходном р-ре=490*0,4=196г;n(H2SO4)=196:98=2моль;W(Na2CO3) в Na2CO3*10H2O=83:263=0.32; m(Na2CO3)в кристаллогидрате=143*0,32=45г;n(Na2CO3)=45:83=0,54моль;         H2SO4+Na2CO3=Na2SO4+CO2+H2O ;n(H2SO4)=0,54моль(затратилось на     нейтрализацию);                             n(H2SO4)осталось в р-ре=2-0,54=1,46моль(они будут взаимодействовать с щелочью);       2NaOH+H2SO4=Na2SO4+2H2O;n(NaOH)=1,46*2=2,92;m(NaOH)=2,92*40=116,8;         2               1W(NaOH)=116,8:1200=0,097(9,7%)

Answer 2

Calculation of the Mass of the Precipitate

To calculate the mass of the precipitate formed when a sufficient amount of copper(II) chloride solution is added to a 200 g solution of sodium hydroxide containing 10% of the active ingredient, we need to consider the reaction between the two compounds.

The balanced chemical equation for the reaction between sodium hydroxide (NaOH) and copper(II) chloride (CuCl2) is as follows:

2NaOH + CuCl2 -> Cu(OH)2 + 2NaCl

From the equation, we can see that 2 moles of sodium hydroxide react with 1 mole of copper(II) chloride to produce 1 mole of copper(II) hydroxide and 2 moles of sodium chloride.

To calculate the mass of the precipitate, we need to determine the number of moles of copper(II) chloride present in the solution. Since the solution contains 10% of the active ingredient, the mass of the copper(II) chloride can be calculated as follows:

Mass of copper(II) chloride = 200 g * 10% = 20 g

Next, we need to convert the mass of copper(II) chloride to moles using its molar mass. The molar mass of copper(II) chloride (CuCl2) is 134.45 g/mol.

Number of moles of copper(II) chloride = Mass of copper(II) chloride / Molar mass of copper(II) chloride Number of moles of copper(II) chloride = 20 g / 134.45 g/mol

Now, we can use the stoichiometry of the balanced equation to determine the number of moles of copper(II) hydroxide formed. From the equation, we know that 1 mole of copper(II) chloride produces 1 mole of copper(II) hydroxide.

Number of moles of copper(II) hydroxide = Number of moles of copper(II) chloride

Finally, we can calculate the mass of the precipitate (copper(II) hydroxide) using its molar mass. The molar mass of copper(II) hydroxide (Cu(OH)2) is 97.56 g/mol.

Mass of the precipitate = Number of moles of copper(II) hydroxide * Molar mass of copper(II) hydroxide

Let's calculate the mass of the precipitate:

Number of moles of copper(II) chloride = 20 g / 134.45 g/mol Number of moles of copper(II) hydroxide = Number of moles of copper(II) chloride Mass of the precipitate = Number of moles of copper(II) hydroxide * Molar mass of copper(II) hydroxide

Please note that the molar mass of copper(II) hydroxide is 97.56 g/mol, but the exact value of the mass of the precipitate cannot be determined without knowing the exact number of moles of copper(II) chloride present in the solution.