Question

Определите молекулярную формулу углеводорода, если известно, что при сгорании 1,4 г его выделилось 4,4 г оксида углерода (IV) и 1,8 г воды. Плотность этого газа по азоту (D(N2)) равна 1, 5.

Answer 1

Дано:

m (УВ) = 1,4г.

m(CO2)=4,4г.

m(H2O)=1,8г

D(N2) = 1,5г

Найти:

CxHy = ?

 

                                               Решение:

1) M(УВ) = D(N2) * M(N2) = 1,5г * 28г/моль=42г/моль

2) CO2(4,4г) = C(х)

  (32г/моль)=12г.

x=4,4г*12г./(32г/моль)=1,65г.

 

3) n(C) = m/M = 1,65г./12г = 0,14 моль

4) H2O(1,8г) = 2H(x)

          18г      = 2г

x= 1,8 * 2 \ 18 = 0,2г

5) n(H) = m\M = 0,2 : 1 = 0,2

           C  :    H

           0,1 моль : 0, 2 моль

            1 : 2 

CH2 - простейшая формула

 M(CH2) = 12 + 2 = 14 г/моль

42г/моль : 14 г.моль = 3

СH2 * 3 = C3H6  - ИСТИННАЯ ФОРМУЛА

Ответ C3H6

 

 

 

 

 

 

Answer 2

Molecular Formula of the Hydrocarbon

To determine the molecular formula of the hydrocarbon, we can use the information provided about its combustion and the resulting products.

Given that 1.4 g of the hydrocarbon produced 4.4 g of carbon dioxide (CO2) and 1.8 g of water (H2O) upon combustion, we can calculate the molar masses of carbon dioxide and water to determine the number of moles produced.

The molar mass of carbon dioxide (CO2) is calculated as follows: - Carbon (C) has a molar mass of 12.01 g/mol. - Oxygen (O) has a molar mass of 16.00 g/mol. - Since carbon dioxide has one carbon atom and two oxygen atoms, the molar mass of carbon dioxide is (12.01 g/mol) + 2 * (16.00 g/mol) = 44.01 g/mol.

The molar mass of water (H2O) is calculated as follows: - Hydrogen (H) has a molar mass of 1.01 g/mol. - Oxygen (O) has a molar mass of 16.00 g/mol. - Since water has two hydrogen atoms and one oxygen atom, the molar mass of water is 2 * (1.01 g/mol) + 16.00 g/mol = 18.02 g/mol.

Now, we can calculate the number of moles of carbon dioxide and water produced: - Moles of carbon dioxide = mass of carbon dioxide / molar mass of carbon dioxide = 4.4 g / 44.01 g/mol - Moles of water = mass of water / molar mass of water = 1.8 g / 18.02 g/mol

Let's calculate the moles of carbon dioxide and water: - Moles of carbon dioxide = 4.4 g / 44.01 g/mol = 0.0999 mol - Moles of water = 1.8 g / 18.02 g/mol = 0.0999 mol

Since the number of moles of carbon dioxide and water is the same, it suggests that the hydrocarbon has a 1:1 ratio of carbon atoms to hydrogen atoms. This indicates that the hydrocarbon is likely a saturated hydrocarbon of the alkane family.

To determine the molecular formula of the hydrocarbon, we need to find the empirical formula first. The empirical formula represents the simplest whole-number ratio of atoms in a compound.

The empirical formula of the hydrocarbon can be determined by dividing the number of moles of each element by the smallest number of moles obtained. In this case, both carbon dioxide and water have the same number of moles, so we can use either of them.

Since the ratio of carbon to hydrogen is 1:1, the empirical formula of the hydrocarbon is CH2.

To find the molecular formula, we need additional information about the molar mass of the hydrocarbon or the ratio of the molar mass to the empirical formula mass. Unfortunately, the molar mass or the ratio is not provided in the given information. Therefore, we cannot determine the specific molecular formula of the hydrocarbon without this additional information.

Please let me know if there is anything else I can help you with!