Thermochemistry

The heat released by the combustion of 'X' g of graphite in the bomb calorimeter causes the temperature of the calorimeter to rise.
The heat absorbed by the calorimeter is given by: $ is the heat capacity of the calorimeter and is the change in temperature.
Given: kJ K Initial temperature K Final temperature K K So, the heat absorbed by the calorimeter is: \) is equal in magnitude but opposite in sign to the heat absorbed by the calorimeter: \) kJ mol .
Since the reaction is carried out at constant volume in a bomb calorimeter, the heat released at constant volume is approximately equal to the enthalpy change (as the number of moles of gas is the same on both sides of the equation).
So, the heat released when 1 mole of graphite burns is 248.
4 kJ.
Let the number of moles of graphite burnt be .
The total heat released by burning 'X' g of graphite is .
\) .
The mass 'X' of graphite burnt is given by: \) $ Therefore, the value of 'X' is 4 g.

Calculate sum of products: Calculate sum of reactants: Calculate reaction enthalpy:

Step 1: Write solubility equilibrium
Let solubility be . In presence of 0.1 M , common ion effect applies: Step 2: Calculate solubility
Step 3: Conclusion
Solubility is .

Formic acid (HCOOH) is a weak acid.
Its conjugate base is formate ion (HCOO ).
For a conjugate acid-base pair, the relationship between the acid dissociation constant ( ) of the acid and the base dissociation constant ( ) of its conjugate base is given by: where is the ionic product of water.
At , .
Given for formic acid = .
We need to find for HCOO .
Calculate : .
So, .
This matches option (3).

We can calculate the temperature (T) using the equation for the equilibrium constant: Substituting the given values, we solve for . After calculation, the correct temperature is found to be 500 K.

Given ionization = 4.242 means
Let initial concentration = M
Then
Also,
Solve for :
M (approx.)
Then
pH =

Step 1: Use relation between and solubility Let be solubility of MX and be solubility of MX. For MX : For MX: Step 2: Take the ratio of solubilities Step 3: Final Answer

Step 1: Understanding Equilibrium Constant Rules When combining chemical reactions: - Reversed reactions: . - Multiplying coefficients: , where is the factor of multiplication. - Summing reactions: . Step 2: Expressing the Given Reaction in Terms of Rewriting the target reaction: Using reactions: - I) formation: The original equation involves , which needs to be reversed and multiplied by 2. - New constant: . - II) formation: This reaction already matches, so is directly used. - III) formation: The original reaction involves , which needs to be multiplied by 3. - New constant: . Step 3: Final Expression Multiplying all equilibrium constants: Conclusion Thus, the correct answer is:

Step 1: Understanding Equilibrium Constant Rules When combining chemical reactions: - Reversed reactions: . - Multiplying coefficients: , where is the factor of multiplication. - Summing reactions: . Step 2: Expressing the Given Reaction in Terms of Rewriting the target reaction: Using reactions: - I) formation: The original equation involves , which needs to be reversed and multiplied by 2. - New constant: . - II) formation: This reaction already matches, so is directly used. - III) formation: The original reaction involves , which needs to be multiplied by 3. - New constant: . Step 3: Final Expression Multiplying all equilibrium constants: Conclusion Thus, the correct answer is:

Formic acid (HCOOH) is a weak acid.
Its conjugate base is formate ion (HCOO ).
For a conjugate acid-base pair, the relationship between the acid dissociation constant ( ) of the acid and the base dissociation constant ( ) of its conjugate base is given by: where is the ionic product of water.
At , .
Given for formic acid = .
We need to find for HCOO .
Calculate : .
So, .
This matches option (3).