The following reactions are carried out in open vessels.
Which of the following correctly shows if the weight of the reaction vessel and contents increases, decreases or remains the same after the reaction as compared to before the reaction?
A. A
B. B
C. C
D. D
Answer:
The reactions are being carried out in an open vessel .
This implies two things:
- The reactants can react with gases in the atmosphere, reactants whose weight does not contribute to the total weight and,
- The gaseous products will be released back into the atmosphere . The product side would hence weigh less (minus the weight of the gases).
In reaction P , since the gas is on the reactant side, the reactants would weigh less than the products. Hence, weight increases.
In reaction Q , there are only solid and aqueous state reactants and products. These contribute to the weight on both sides. Hence, weight remains the same .
In reaction R , the gas is on the products side. The gaseous Sulphur Trioxide is released
into the atmosphere and hence does not contribute to the weight. This leads to a decrease in weight.
Therefore, the correct answer is D .