Question

.При сжигании органического соединения массой 4.2 г получили оксид углерода (IV) массой 5,4 г. Относительная плотность этого соединения по воздуху 2,9. Выведите молекулярную формулу органического соединения.

Answer 1

M(в-ва) = 2,9 * 29 = 84,1 г/моль
n(CO2) = 13.2 / 44 = 0.3 моль
n(H2O) = 5.4 / 18 = 0.3 моль
m(C) = 0.3 * 12 = 3.6 г
n(H) = 2 * n(H2O) = 0.3 * 2 = 0.6 моль
m(H) = 0.6 * 1 = 0.6 г
m(H) + m(C) = 0.6 + 3.6 = 4.2 г
значит кислорода тут нет 
C : H = 0.3 : 0.6 = 3 : 6
M(C3H6)простейшее = 42 г/моль
M(в-ва) / M(C3H6) = 84 / 42 = 2 => в-во - С6H12

Answer 2

Calculation of Molecular Formula

To determine the molecular formula of the organic compound, we need to analyze the given information.

- Mass of the organic compound: 4.2 g - Mass of carbon dioxide (CO2) produced: 5.4 g - Relative density of the compound with respect to air: 2.9

To find the molecular formula, we can follow these steps:

1. Calculate the moles of carbon dioxide produced: - The molar mass of carbon dioxide (CO2) is 44 g/mol. - The moles of carbon dioxide produced can be calculated using the formula: moles = mass / molar mass. - Moles of CO2 = 5.4 g / 44 g/mol = 0.1227 mol.

2. Calculate the moles of carbon in the organic compound: - Since carbon dioxide (CO2) is produced, the carbon in the organic compound is equal to the carbon in CO2. - The molar ratio of carbon to carbon dioxide is 1:1. - Moles of carbon = 0.1227 mol.

3. Calculate the empirical formula of the organic compound: - The empirical formula represents the simplest whole number ratio of atoms in a compound. - To find the empirical formula, we need to know the molar mass of carbon and the empirical formula mass. - The molar mass of carbon is 12 g/mol. - The empirical formula mass can be calculated using the formula: empirical formula mass = molar mass / moles. - Empirical formula mass = 12 g/mol / 0.1227 mol = 97.7 g/mol.

4. Determine the empirical formula: - Divide the molar mass of each element by the empirical formula mass to find the subscripts in the empirical formula. - Since the relative density of the compound is not provided, we cannot determine the exact molecular formula. However, we can still find the empirical formula. - Let's assume the empirical formula is CxHyNz. - From the given information, we know that the compound contains only carbon, hydrogen, and nitrogen. - The empirical formula mass of CxHyNz can be calculated using the atomic masses of carbon (12 g/mol), hydrogen (1 g/mol), and nitrogen (14 g/mol). - The empirical formula mass = 12x + 1y + 14z. - We need to find the values of x, y, and z.

5. Use the given information to find the values of x, y, and z: - From the given information, we know that the compound contains 4.2 g of carbon and has a relative density of 2.9. - The relative density is the ratio of the molecular mass of the compound to the molecular mass of air. - The molecular mass of air is approximately 29 g/mol. - The molecular mass of the compound can be calculated using the formula: molecular mass = empirical formula mass x relative density. - Molecular mass = 97.7 g/mol x 2.9 = 283.33 g/mol.

6. Calculate the values of x, y, and z: - We can set up a system of equations using the given information. - From the equation 12x + 1y + 14z = 283.33, we can solve for x, y, and z. - However, without additional information, it is not possible to determine the exact values of x, y, and z.

Therefore, based on the given information, we can determine the empirical formula of the organic compound as CxHyNz, but we cannot determine the exact molecular formula without additional information