Ravi was performing some experiments related to the laws of chemical combination in
the science laboratory under the guidance of his chemistry teacher Mr. John. Ravi found
that when be burned 1 gram of hydrogen gas in 8 grams of oxygen gas in a closed
vessel, he obtained 9 grams of water. He repeated this experiment many times but
obtained the same result every time.
i) Write a balanced chemical equation for the reaction between hydrogen and oxygen
to form water. Also write the names of all the substances involved below their
formulae in the equation.
ii) What are the reactants and products in the above reaction?
iii) Which law of chemical combination is illustrated by the fact that when Ravi
burned 1 g of hydrogen in 8 g oxygen. be obtained 9 g of water?
iv) What values are displayed by Ravi in this episode?
Answers
Answer:law of conservation of mass
Explanation:
(a) The balanced chemical equation for the reaction between hydrogen and oxygen to form water can be written as :
2H2Hydrogen+O2Oxygen→2H2OWater
(b) (i) The reactants in this reaction are : Hydrogen and Oxygen
(ii) The product in this reaction is : Water
(c) Here, Mass of reactants = Mass of hydrogen + Mass of oxygen
=1g+8g
9g
And, Mass of product = Mass of water
=9g
Now, since the mass of product (9g) is equal to the mass of reactants (9g), therefore, the given experiemental data illustrates the law of conservation of mass in chemical reactions
(d) Out answer will be governed by the law of constant proportions. It has been given in this question that when 1g of hydrogen is burned in 8g of oxygen of oxygen, then 9g of water is always obtained. Now, since hydrogen and oxygen combine in the fixed proportion of 1 : 8 by mass to produce 9g of water, therefore, the same mass of water (9g water) will be obtained even if we burn 1g of hydrogen in 10g of oxygen. The extra oxygen (10 - 8 = 2g oxygen) will remain unreacted in this case
(e) The various values displayed by Ravi in this episode are (i) Knowledge of the law of conservation of mass and law of constant proportions in chemical reactions and (ii) Application of knowledge in solving problems.