Long Answer TypeA welding fuel gas contains carbon and hydrogen only. Burning a small space of it in oxygen gives 3.38 g carbon dioxide, 0·690g of water and no other products. A volume of 10·0L (measured at STP) of this welding gas is found to weigh 11·6g. Calculate: (i) empirical formula (ii) molar mass of the gas and (iii) molecular formula.
Butyric acid contains only C, H and O, 4.24mg sample of butyric acid is completely burnt. It gives 8.45mg of carbon dioxide and 3.46mg of water. What is the mass percentage of each element in butyric acid?
Short Answer TypeIf the elemental composition of butyric acid is found to be 54.2%C, 9.2%H and 36.6%O, determine the empirical formula.
The molecular mass of butryic acid was determined by experiment to be 88 amu. what is the molecular formula?
Long Answer TypeChemical equation is a symbolic representation of actual chemical change in terms of symbols and formulae of the reactants and products. The substances which react among themselves are called reactants. These are written on left hand side of the equation. The substances formed during the chemical change are called products. These are written on the right hand side of the equation. For example, reaction between zinc and hydrochloric acid to form zinc chloride and hydrogen can be represented by a chemical equation.
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Essentials of a chemical equation. A chemical equation must satisfy the following conditions:
(i) It should represent a true chemical change i.e. the change represented by the chemical equation should be practically possible.
For example, the equation
is not a true chemical equation since copper does not react with sulphuric acid to produce copper sulphate and hydrogen.
(ii) It should be arithmetically balanced.
Atoms of each element on both the sides of the arrow 
must be equal. For example,
is an arithmetically balanced equation.
(iii) It should be molecular. If any elementary gas takes part in a chemical equation it must be expressed in the molecular form e.g.
What are the implications of a chemical equation?
Or
What informations are conveyed by a chemical equation?
How can we make a chemical equation more informative?
Or
How can we remove the drawbacks or limitations of a chemical equation?
Short Answer TypeWrite balanced chemical equation for the following reactions making them as informative as you can:
(i) Reaction between magnesium carbonate and dilute sulphuric acid to form an aqueous solution of magnesium sulphate, carbondioxide gas and water.
(ii) Reaction between methane gas (CH4) and oxygen gas to produce carbondioxide, water vapours and heat.
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