5)when 3.0 g of C is burnt 8.0 g of oxygen,11.o g of CO is produced.What mass of CO will be formed when 3.0 g of C is burnt 50.0 g of oxygen? Which law of chemical combination will govern your answer? state the law

Asked by rohan | 20th Nov, 2013, 10:06: AM

Expert Answer:

Carbon and oxygen combine to form carbon dioxide, CO2. The ratio of carbon to oxygen by mass is 3:8 as the ratio of atomic mass of C to molecular mass of oxygen is 12:32 or 3:8.

When 3.0g of carbon burns in 8.0 g of oxygen, 11.0 g of carbon dioxide is formed. Law of conservation of mass is obeyed.

 

   C      +       O2     →      CO2

  3.0g           8.0g            11.0g

 

In forming CO2, the ratio of carbon to oxygen by mass cannot change; it is fixed according to the law of constant proportions. The ratio of C to oxygen by mass is always 3:8.

When 3.0g of carbon burns in 50.0g of oxygen only 8.0g of O2 is used in making CO2.

The balance (50.0 – 8.0) g = 42.0 g of oxygen remains unreacted.

 

   C     +     O2        +      O2       →        CO2      +     O2

   3.0g        8.0g            42.0g                11.0g        42.0 g

    (Reacted)             (Unreacted)                Total 53.0g

 

Only 11.0g of carbon dioxide is formed, rest 42.0 g of oxygen remains free. In this way, both the laws of conservation of mass and law of constant proportions are obeyed.

Law of conservation of mass states that mass can neither created nor destroyed in a chemical reaction.

Law of constant proportion states that, In a chemical substance elements are always present in a definite proportion by mass.

Answered by Hanisha Vyas | 20th Nov, 2013, 11:12: AM

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