Question

Сплав железа с углеводом (чугун) массой 90 г растворили в избытке соляной кислоты, при этом выделилось 33,6 л газа(н.у.). Определите массовую долю ( в процентах) железа в чугуне.

Answer 1

 х г                                                     33,6 л

$Fe+2HCl=FeCl_2+H_2$

56 г                                                     22,4 л

1. Определим массу чистого железа в образце(сплаве):

 при взаимодействии 56 г железа выделяется 22,4 л водорода, а

 при  --  //  --            х г___________________33,6 л, откуда

 х=56*33,6/22,4=84 г

2. Отнеся эту массу к массе всего сплава,и определим массовую долю железа в нем:

 w(Fe)=m(Fe)/m(сплава)=84/90=0,93 или 93%

Answer 2

Calculation of Iron Mass Fraction in Cast Iron

To determine the mass fraction of iron in cast iron, we need to use the given information about the reaction between iron and hydrochloric acid.

The reaction can be represented as follows:

Fe + 2HCl → FeCl2 + H2

From the reaction equation, we can see that 1 mole of iron (Fe) reacts with 2 moles of hydrochloric acid (HCl) to produce 1 mole of iron(II) chloride (FeCl2) and 1 mole of hydrogen gas (H2).

Given: - Mass of cast iron (Fe + C) = 90 g - Volume of gas produced (at standard temperature and pressure) = 33.6 L

To determine the mass fraction of iron in cast iron, we need to find the moles of iron and the moles of iron(II) chloride produced in the reaction.

Moles of Iron

To find the moles of iron, we need to convert the mass of cast iron to moles using the molar mass of iron.

The molar mass of iron (Fe) is approximately 55.845 g/mol.

Using the given mass of cast iron (90 g) and the molar mass of iron, we can calculate the moles of iron:

Moles of iron = Mass of iron / Molar mass of iron

Moles of iron = 90 g / 55.845 g/mol

Calculating this value gives us the moles of iron.

Moles of Iron(II) Chloride

From the balanced chemical equation, we know that 1 mole of iron reacts to produce 1 mole of iron(II) chloride.

Therefore, the moles of iron(II) chloride produced in the reaction are equal to the moles of iron.

Mass Fraction of Iron

The mass fraction of iron in cast iron can be calculated using the following formula:

Mass fraction of iron = (Moles of iron / Total moles) * 100%

Since the moles of iron(II) chloride produced are equal to the moles of iron, the total moles are also equal to the moles of iron.

Using the calculated moles of iron, we can now calculate the mass fraction of iron in cast iron.

Calculation Steps Summary:

1. Calculate the moles of iron using the given mass of cast iron and the molar mass of iron. 2. Calculate the moles of iron(II) chloride produced. 3. Calculate the mass fraction of iron using the moles of iron and the total moles.

Please note that the molar mass of iron and the balanced chemical equation are taken from general chemistry knowledge and not from the provided search results.

Let's perform the calculations.