Question

Під час хлорування алкену масою 1,44 г добуто дихлоропохідну речови- ну масою 3,27 г. Визначте молекулярну формулу вуглеводню. (Напишіть, як нормальну розв’язану задачу, а не 2 формули і все. Окей? )

Answer 1

при хлорировании алкена хлор присоединяется к двойной связи:

CnH2n+Cl2=>CnH2nCl2

найдем массу хлора:

m(Cl2)=m(CnH2nCl2)-m(CnH2n)=3,27-1,44=1,83г

n(Cl2)=1,83/71≈0,026 моль

n(CnH2n)=n(Cl2)

Mr(CnH2n)=m(CnH2n)/n(CnH2n)=1,44/0,026≈55

молекулярная масса данного алкена =55 но общая формула молекулярной массы алкенов — 14n

14n=55

n=55/14

n=4

C4H8

Answer 2

Problem Analysis

We are given that during the chlorination of an alkene with a mass of 1.44 g, a dichloro derivative with a mass of 3.27 g is obtained. We need to determine the molecular formula of the hydrocarbon.

Solution

To solve this problem, we need to follow a step-by-step approach:

1. Determine the number of moles of the alkene and the dichloro derivative. 2. Find the empirical formula of the hydrocarbon. 3. Determine the molecular formula of the hydrocarbon.

Let's proceed with the calculations.

Step 1: Determine the number of moles

To find the number of moles, we can use the formula:

Number of moles = Mass / Molar mass

The molar mass of an alkene can vary depending on its specific structure. Since we don't have information about the specific alkene, we cannot calculate the exact molar mass. However, we can assume a general molar mass for an alkene, such as 28 g/mol, which is the molar mass of ethene (C2H4).

Using this assumption, we can calculate the number of moles of the alkene:

Number of moles of alkene = Mass of alkene / Molar mass of alkene

Let's substitute the given values:

Mass of alkene = 1.44 g Molar mass of alkene = 28 g/mol (assumed value)

Number of moles of alkene = 1.44 g / 28 g/mol

Calculating this, we find that the number of moles of the alkene is approximately 0.0514 mol.

Similarly, we can calculate the number of moles of the dichloro derivative using its mass and molar mass. Again, we don't have information about the specific dichloro derivative, so we cannot calculate the exact molar mass. However, we can assume a general molar mass for a dichloro derivative, such as 98 g/mol, which is the molar mass of 1,2-dichloroethane (C2H4Cl2).

Using this assumption, we can calculate the number of moles of the dichloro derivative:

Number of moles of dichloro derivative = Mass of dichloro derivative / Molar mass of dichloro derivative

Let's substitute the given values:

Mass of dichloro derivative = 3.27 g Molar mass of dichloro derivative = 98 g/mol (assumed value)

Number of moles of dichloro derivative = 3.27 g / 98 g/mol

Calculating this, we find that the number of moles of the dichloro derivative is approximately 0.0334 mol.

Step 2: Find the empirical formula

The empirical formula represents the simplest whole number ratio of atoms in a compound. To find the empirical formula, we need to determine the ratio of moles of each element present in the compound.

In this case, the alkene contains only carbon and hydrogen, while the dichloro derivative contains carbon, hydrogen, and chlorine.

From the number of moles calculated in Step 1, we can determine the ratio of moles of carbon, hydrogen, and chlorine in the dichloro derivative:

- Carbon: 0.0334 mol - Hydrogen: 0.0334 mol - Chlorine: 0.0334 mol

To simplify the ratio, we can divide each value by the smallest value, which is 0.0334 mol:

- Carbon: 0.0334 mol / 0.0334 mol = 1 - Hydrogen: 0.0334 mol / 0.0334 mol = 1 - Chlorine: 0.0334 mol / 0.0334 mol = 1

Therefore, the empirical formula of the hydrocarbon is CHCl.

Step 3: Determine the molecular formula

The empirical formula represents the simplest ratio of atoms in a compound. To determine the molecular formula, we need to find the actual number of atoms of each element in the compound.

To do this, we need additional information about the molar mass of the hydrocarbon. Without this information, we cannot determine the molecular formula.

Therefore, based on the given information, we can only determine the empirical formula of the hydrocarbon, which is CHCl.

Please note that the assumption of the molar masses for the alkene and dichloro derivative was made to demonstrate the calculation steps. In a real-world scenario, the specific alkene and dichloro derivative would need to be known to calculate the molar masses accurately.

I hope this helps! Let me know if you have any further questions.