Law Of Chemical Equilibrium And Equilibrium Constant

To determine for the given reaction at 300 K, we use the relationship between and : Given: -
- Temperature,
- Gas constant,
- Change in the number of moles of gas,
Step 1: Determine For the reaction:
- Reactants: 1 mole of
- Products: 1 mole of + 1 mole of
Step 2: Calculate Using the formula: Substitute the values: Final Answer: This corresponds to option (2).

Step 1: Define the ICE Table
Let the initial concentration of be and let be the amount dissociated:

Step 2: Apply the Equilibrium Expression

Step 3: Solve for

Step 4: Find Equilibrium Concentrations

Step 1: Define Dissociation Equation For a weak acid HA dissociating in water:
Step 2: Compute Concentrations Given initial concentration:

Step 1: Initial setup: Given the reaction: At equilibrium, we know the concentration of and are and , respectively. Also, we are provided with the equilibrium constant: where . Since 2 moles of were initially present in a 1 L flask, the initial concentration of is: At equilibrium, the amount of and present will be given by the expression of and .

Step 2: Adding 1 mole of to the flask: One mole of is added to the flask, bringing the new total moles of to 3 moles in the same 1 L flask. Thus, the new initial concentration of becomes: Now, the system is heated to again to establish equilibrium.

Step 3: Reaching new equilibrium: The equilibrium constant still holds: At the new equilibrium, let be the final concentration of and be the final concentration of . Using stoichiometry, the change in the concentration of can be represented as: where is the amount of that dissociates. Thus, the concentration of at equilibrium will be , as two moles of are produced per mole of . At equilibrium: Substitute these into the equilibrium expression:

Step 4: Solve the equation: Multiply both sides by : Rearrange the terms to form a quadratic equation: Solve this quadratic equation using the quadratic formula: Taking the positive root: Thus, the concentration of at equilibrium is: Thus, the final concentration of is . The value of is approximately . Thus, the correct answer is option (3).

Step 1: Statement (i) is true because saline hydrides like NaH react with water to produce hydrogen gas ( ).
Step 2: Statement (ii) is false because most industrial hydrogen is produced from natural gas, not coal.
Step 3: Statement (iii) is true because commercially available typically contains 3% hydrogen peroxide. Thus, the correct answer is (B) i, iii only.