2.In a chemical reaction 6g of carbon is burnt in 16g of oxygen to produce 22g of carbondioxide. Show that these observations are in agreement with the law of conservation of mass.
Answers
22 g of CO
2
will be formed when 6 g of carbon is burnt in 32 g of oxygen.
C+O
2
→CO
2
The atomic mass of C is 12 g/mol. The molecular masses of O
2
and CO
2
are 32 g/mol and 44 g/mol respectively.
12 g C will combine with 32 g O
2
to form 44 g CO
2
.
6 g C will combine with 32 g O
2
to form 22 g CO
2
.
Hence, the option (D) is the correct answer.
Answer:
1. In a reaction 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass carbonate.
Ans.
Sodium carbonate + Ethanoic acid → Sodium ethanoate + Carbon dioxide + Water
5.3 g + 6 g → 8.2 g + 2.2 g + 0.9 g
LHS RHS
11.3 g = 11.3 g
(Mass of reactant) (Mass of product)
This shows, that during a chemical reaction mass of reactact = mass of product.
2. Hydrogen and oxygen combine in the ratio of 1 : 8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?
Ans. Ratio of H : O by mass in water is:
Hydrogen : Oxygen → H2O
1 : 8 = 3 : x