Q1. Name the two solutions used in the experiment.
Answer: Sodium thiosulphate and hydrochloric acid.
Q2. What is the molecular formula of sodium thiosulphate?
Q3. What is the concentration of sodium thiosulphate used in this experiment?
Answer: 0.1 M
Q4. What is the concentration of hydrochloric acid used in this experiment?
Q5. Write the equation for the reaction between sodium thiosulphate and hydrochloric acid.
Answer: Na2S2O3 + 2HCl → 2NaCl + SO2 + H2O + S
Q6. What will happen when dilute hydrochloric acid is added to sodium thiosulphate solution.
Answer: Yellow precipitate will be formed.
Q7. What is the yellow substance produced in sodium thiosulphate and hydrochloric acid reaction?
Q8. What is the effect of concentration on the rate of a reaction?
Answer: The rate of reaction increases with concentration. A higher concentration of a reactant leads to more collisions of reactant in a specific time, thereby increasing the reaction rate.
Q9. When should we start the stopwatch?
Answer: We should start the stopwatch after pouring half of the hydrochloric acid into the sodium thiosulphate solution flask.
Q10. What is the importance of concentrated nitric acid?
Answer: Concentrated nitric acid is used to wash the apparatus used in the experiment.
Q11. How will you plot a graph between the concentration and time of reaction?
Q12. What is the rate equation for a first-order reaction?
Answer: k = 2.303 / t log a / a-x
Q13. What are the factors that affect the rate of a reaction?
Answer: Various factors can affect the rate of a chemical reaction.
- Concentration of the reactant
- Physical state
Q14. What is the law of mass action?
Answer: Law of Mass Action states that the rate of the chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation.
Q15. For which type of reactions, do order and molecularity have the same value?
Answer: Order and molecularity have the same value for elementary reactions taking place in a single step.
Q16. What is the effect of temperature on the rate of a reaction?
Answer: The rate of reaction increases with temperature. With the increasing temperature, the energy possessed by the reacting species increases. As a result, more species are in a position to cross the activation barrier. Therefore the reaction rate increases with a temperature rise.
Q17. Write the rate equation for the reaction 2A + B → C if the reaction order is zero.
Answer: The rate equation for the reaction 2A + B → C in the zero-order reaction is
Rate = k [A]0 [B]0 = k
Q18. Why can’t the molecularity of any reaction be equal to zero?
Answer: The molecularity of any reaction is the number of the reactant molecules or species colliding simultaneously in an elementary reaction. A minimum of one reactant is needed to initiate a chemical reaction. Therefore, the molecularity of the reaction cannot be zero.
Q19. Why is a reaction with a molecularity of more than three rare?
Answer: Reaction with a molecularity of more than three is rare because a simultaneous collision between more than three particles is rare.
Q20. What are the units of the rate of reaction?
Answer: Mol -1 L -1 sec -1
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