Hydrolysis of a compound A, C7H6cl2 was carried out by refluxing with excess potassium hydroxide solution. the resulting solution was acidified with dilute HNO3 acid and excess silver nitrate was added to precipitate the chloride ions as silver chloride. 0.718g of silver chloride was formed from 0.805g of A.
1. calculate the number of chlorine atoms present in each molecule of A liberated by hydrolysis.
2. Suggest an explanation for result in no.1
%Cl in C7H6Cl2 = (2*35.44/161.03)*100 = 44.02% or 44.0% Cl to 3 s.f.
%Cl from AgCl data.
mols AgCl = g/molar mass = 0.718/143.32 = 0.005. mols Cl = 0.005. g Cl = 0.005x 35.44 = 1.41E-4. %Cl in C7H6Cl2 = (g Cl/mass sample)*100 = (1.41E-4/0.805)*100 = 22.05% or 22.1% to 3 s.f.
So there is 44% Cl in the initial compound but after hydrolysis you found only 22.1% which is just half the value you might expect. That means that 1 of the Cl atoms is attached to a coordination sphere and the other Cl atom is outside the coordination sphere. So the ionic Cl was hydrolyzed
Step 1: Calculate the number of moles of silver chloride (AgCl) formed:
To calculate the number of moles of AgCl, we need to use the molar mass of AgCl.
The molar mass of AgCl = 107.87 g/mol (atomic mass of Ag) + 35.45 g/mol (atomic mass of Cl) = 143.32 g/mol
Using the given mass of AgCl (0.718g), we can calculate the number of moles using the formula:
Number of moles = mass / molar mass
Number of moles of AgCl = 0.718g / 143.32 g/mol = 0.005 mol
Step 2: Calculate the number of moles of compound A:
To calculate the number of moles of compound A, we need to use the given mass of A (0.805g) and its molar mass.
The molar mass of C7H6Cl2 = (7 * 12.01 g/mol) + (6 * 1.01 g/mol) + (2 * 35.45 g/mol) = 197.05 g/mol
Number of moles of A = 0.805g / 197.05 g/mol = 0.0041 mol
Step 3: Calculate the number of Cl atoms per molecule of A:
To calculate the number of Cl atoms per molecule of A, we need to use the molar ratio between AgCl and A.
From the chemical equation, we know that 2 moles of AgCl are formed for every 1 mole of A.
Therefore, the number of chlorine atoms in each molecule of A = 2 * 0.005 mol / 0.0041 mol = 2.439 chlorine atoms
Answer to question 1: The number of chlorine atoms present in each molecule of A liberated by hydrolysis is 2.439.
Step 4: Suggest an explanation for the result in question 1:
The result of 2.439 chlorine atoms per molecule of A indicates that there are more than one chloride (Cl) groups in each molecule of A. This suggests that A is likely a compound with multiple substitution sites for chlorine atoms. The excess silver nitrate added after acidification with dilute HNO3 reacts with the chloride ions liberated during hydrolysis to form silver chloride precipitate, confirming the presence of chloride ions in compound A.
To answer your questions, let's break down the given information and go step by step.
1. To calculate the number of chlorine atoms present in each molecule of A liberated by hydrolysis, we need to use the given data.
We know that 0.805g of compound A was used in the hydrolysis reaction, and 0.718g of silver chloride was formed as a result.
To find the number of chlorine atoms, we will use the molar mass of silver chloride (AgCl). The molar mass of Ag is 107.87 g/mol, and the molar mass of Cl is 35.45 g/mol.
Since the molar mass of AgCl is the sum of the molar masses of Ag and Cl, we can calculate it as follows:
Molar mass of AgCl = Molar mass of Ag + Molar mass of Cl
= 107.87 g/mol + 35.45 g/mol
= 143.32 g/mol
Next, we can calculate the number of moles of AgCl using the formula:
Number of moles = Mass / Molar mass
Number of moles of AgCl = 0.718g / 143.32 g/mol = 0.0050 mol
Since AgCl contains one chloride ion (Cl-) per molecule, the number of moles of Cl- will also be 0.0050 mol.
Now, we can calculate the number of chlorine atoms using Avogadro's number (6.022 x 10^23 atoms/mol):
Number of chlorine atoms = Number of moles of Cl- x Avogadro's number
= 0.0050 mol x 6.022 x 10^23 atoms/mol
= 3.011 x 10^21 chlorine atoms
Therefore, there are approximately 3.011 x 10^21 chlorine atoms in each molecule of compound A.
2. The result obtained in question 1 can be explained by understanding the hydrolysis reaction and the formation of silver chloride.
In the reflux reaction between compound A (C7H6Cl2) and excess potassium hydroxide (KOH), the hydrolysis of A takes place. The hydrolysis reaction involves the breaking of chemical bonds using water (H2O).
C7H6Cl2 + 2KOH + H2O → C6H6 + 2KCl + 2H2O
In this reaction, two chloride ions (Cl-) are liberated as potassium chloride (KCl) along with water (H2O) and the formation of compound C6H6 (benzene).
When the resulting solution is acidified with dilute HNO3 acid and excess silver nitrate (AgNO3) is added, a precipitation reaction occurs as silver chloride (AgCl) is formed:
Ag+ (aq) + Cl- (aq) → AgCl (s)
The formation of silver chloride can be used to detect the presence of chloride ions. The stoichiometry of this reaction indicates that one chloride ion (Cl-) reacts with one silver ion (Ag+) to form one molecule of silver chloride (AgCl), which is a white precipitate.
By measuring the mass of the silver chloride formed, we can determine the amount of chloride ions present and, consequently, the number of chlorine atoms originally present in compound A.
Therefore, the result obtained in question 1 suggests that compound A contains two chlorine atoms per molecule, which are liberated as chloride ions during hydrolysis.