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प्रश्न
Why should an equation be balanced? Explain with the help of a simple equation.
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उत्तर
According to the law of conservation of mass, 'matter can neither be created nor can it be destroyed'. This is possible only if the total number of atoms on the reactants side is equal to the total number of atoms on the products side. Thus, a chemical reaction should always be balanced.
e.g. KNO3 → KNO2 + O2
In this equation, the number of atoms on both sides is not the same, and the equation is not balanced.
The balanced form of this equation is
2KNO3 → 2KNO2 + O2
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संबंधित प्रश्न
Balance the given chemical equation:
C + CO2 → CO
State one characteristic of the chemical reaction which takes place when lemon juice is added gradually to potassium permanganate solution.
When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.
(a) Name any two metals which can behave like metal X.
(b) Name any two acids which can behave like acid Y.
(c) Name the gas Z.
(d) Is the gas Z lighter than or heavier than air?
(e) Is the reaction between metal X and dilute acid Y, exothermic or endothermic?
(f) By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.
Balance the following chemical equation :
FeS + HCl → FeCl2 + H2S
\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
0.02 moles of pure MnO2 is heated strongly with conc. HCl. Calculate the mass of salt formed.
Write word equation for the following molecular equation:
\[\ce{H2 [g] + Cl2 [g] ->[sunlight] 2HCl}\]
Word equation:
State which form of energy is utilised in the above chemical reaction.
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – zinc carbonate.
\[\ce{2KClO3->[MnO2] 2KCl + 3O2[g] - is a balanced equation.}\]
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Match the columns.
| Reactants | Products | Types of chemical reaction | ||
| 1. | MgH2 | → | Mg + H2 | Endothermic |
| 2. | 2H2S + SO2 | → | 3S + 2H2O | Oxidation |
| 3. | CaO + H2O | → | Ca(OH)2 + heat | Exothermic |
| Redox | ||||
Balance the given chemical reaction as per the instructions below.
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Make a list of the elements in the chemical equation.
