Question

In order to verify the law of conservation of mass, a student mixed 6.3 g of sodium
carbonate and 15 g of ethanoic acid in a conical flask. After experiment, he
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weighed the flask again. The weight of the residue in the flask was only 18g. He
approached the teacher who guided him to carry the experiment in a closed flask
with a cork. There was no difference in weight of the flask before and after the
experiment.
Answer the following questions
What was the mistake committed by the student?
i. Why did not the two weights match earlier?
iii. How did the teacher help him?
iv. What lesson was learnt by the students?
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Answer 1

We know that,

According to the law of conservation of mass,

mass of reactants= mass of products

mass of sodium bicarbonate + acetic acid = mass of CO₂ + Residue

6.3g + 15.0g = 21.3g

so mass of CO₂ = 21.3g - 18.0g =3.3g

Answer 2

"The experiment Reviewing by student"

Explanation:

The below should be followed while doing the experiments:

• The students should be wear a hand cloves while doing the chemical experiments.
• They should not disturb the chemicals while experiments is in rest in the laboratory.
• The student did not measure the reaction correctly that is why the mistakes has came.
• The two weights are mismatched because of the extra added water in it.
• The teacher helps him by the doing the experiment from first.
• The Lesson was learnt by the student is should not do any unknown work by themselves.