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प्रश्न
State the various characteristics of chemical reactions.
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उत्तर
- Evolution of gas: Zinc and dilute sulphuric acid react to form zinc sulphate with the evolution of hydrogen gas.
- Formation of precipitate: Sulphuric acid and barium chloride react to form white precipitates of barium sulphate.
- Change in colour: The purple colour of the potassium permanganate solution, upon the addition of citric acid, changes to a colourless solution.
- Change in temperature: Barium hydroxide and ammonium chloride react to form barium chloride, ammonia and water. This is an endothermic reaction in which heat is absorbed, causing the temperature to fall.
- Change in state: Combustion of candle wax (solid) leads to the formation of water (liquid) and carbon dioxide (gas).
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संबंधित प्रश्न
Write the balanced chemical equation for the following reaction.
\[\ce{Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride}\]
With the help of an appropriate example, justify that some of the chemical reactions are determined by the evolution of a gas.
Give a chemical equation for the reaction involved in the above case.
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.
A white precipitate can be obtained by adding dilute sulphuric acid to:
(a) CuSO4 solution
(b) Nacl solution
(c) BaCl2 solution
(d) Na2SO4 solution
A colourless lead salt, when heated, produces a yellow residue and brown fumes.
(a) Name the lead salt.
(b) Name the brown fumes.
(c) Write a chemical equation of the reaction involved.
Explain the following reaction with one suitable example .
Decomposition reaction
Write your observation and name the product when zinc reacts with dilute hydrochloric acid.
Write down what you understood from the following chemical reaction.
AgNO3(aq) + NaCI(aq) → AgCI ↓ + NaNO3(aq)
Write the chemical equation for the following word equation and balance them.
Carbon + Oxygen → Carbon dioxide
Balance the following equation:
S + H2SO4 → SO2 + H2O
Why should an equation be balanced? Explain with the help of a simple equation.
Name the substance that is getting oxidised in the thermit process.
Write word equation for the following molecular equation:
\[\ce{CaCO3 + 2HCl ->[\triangle] CaCl2 + H2O + CO2 [g]}\]
Word equation:
State which characteristic does [g] in the above reaction indicate. The word equation of:
Balance the following simple equation:
C + O2 → CO
Balance the following simple equation:
FeCl2 + Cl2 → FeCl3
Write a balanced equation for the following word equation:
Iron + Hydrochloric acid → Iron [II] chloride + Hydrogen
Give a balanced equation by partial equation method, [steps are given below].
The reaction of excess ammonia with chlorine – Ammonia as a reducing agent
- Ammonia first reacts with chlorine to give hydrogen chloride and nitrogen.
- Hydrogen chloride then further reacts with excess ammonia to give ammonium chloride.
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
3CuO + NH3 → 3Cu + 3H2O + N2
What is a chemical equation?
A student took a small amount of copper oxide in a conical flask and added dilute hydrochloric acid to it with constant stirring. He observed a change in colour of the solution.
- Write the name of the compound formed and its colour.
- Write a balanced chemical equation for the reaction involved.
