Chemical Equations- Question List

Short Q&A (2 or 1 marks)

  1. What is the difference between physical change and chemical change?
  2. How do we know that a chemical reaction has taken place?
  3. What happens when CaO is treated with water?
  4. What temperature changes do you observe when CaO is treated with water?
  5. Give an example for precipitation reaction.
  6. On mixing Zn granules with an acid, which gas is released? How would you test it?
  7. What are reactants?
  8. What are products?
  9. What is a chemical equation?
  10. What is a balanced chemical equation?
  11. Why should chemical equation be balanced?
  12. While white washing of walls, an aqueous solution of calcium hydroxide is painted on the wall. A couple of days later, why does the wall turn white?
  13. What is meant by endothermic reaction?
  14. In a chemical equation, what does an upward arrow indicate?
  15. What does coefficients in a balanced chemical equation indicate?
  16. What is meant by limiting reagent?
  17. 1 mole of any gas occupies ___ volume
  18. What is a skeleton equation?
  19. What does the symbol (aq) represent in a chemical equation?
  20. What is wrong in the following chemical equations. Correct it.
    • H2 + O —-> H2O
    • Ca(OH) + CO2  —-> Ca(CO3) + H2O
  21. Why is respiration considered as an exothermic reaction?
  22. On adding dil.HCl to copper oxide, the solution formed is blue-green. Write the name and molecular formula of the new compound formed.
  23. Why is photosynthesis considered an endothermic reaction?
  24. Complete the following reaction
    • Pb(NO3)2 + 2KI —-> ______ + ______
    • Cu2S + O2 —–> ______ + _______
  25. Write a chemical equation for the following reactions
    1. Magnesium ribbon is heated in presence of air, producing white flame and forms white powder called Magnesium Oxide.
    2.  Sodium metal reacts with water to form sodium hydroxide and the hydrogen gas.

Balance the following equations

  • Na + O2 —> Na2O
  • H2O2 —.> H2O + O2
  • BaCl2 + H2SO4 —> BaSO4 + HCl
  • Fe + O2 —> Fe2O3
  • Al2(SO4)3 + NaOH —> Al(OH)3 + Na2(SO4)
  • Al + CuCl2 —> AlCl3 + Cu
  • Al(OH)3 —-> Al2O3 + H2O
  • N2 + H2 —> NH3
  • KClO3 —-> KCl + O2
  • MnO2 + HCl —-> MnCl2 + Cl2 + H2O
  • C3H8 + O2 —-> CO2 + H2O
  • SO2 + O2 —-> SO3
  • Cu(SO4) + NaOH —-> Cu(OH)2 + Na2SO4
  • Pb(NO3)2 —-> PbO + NO2 + O2
  • FeSO4 —-> Fe2O3 + SO2 + SO3

4 Marks Q&A

  1. What information do you obtain from a balanced chemical equation? Explain with examples.
  2. Heat is liberated in the reactions where water was added to Calcium Oxide and when Hydrochloric acid is added to Zinc granules. Ramu said as heat is liberated, both reactions are of the same type. Eswar was of the opinion that both reactions are different. Who do you think is correct? Write equations and explain.
  3. Write the steps involved in balancing a chemical equation. Elucidate.
  4. X is a brown shining element with atomic number one unit greater than Ni. When X is burnt in air, it turns black. Wat is X? What is the new substance?
  5. When the solution of substance X is added to a solution of KI, then a yellow solid is formed as precipitate is formed. What is X? Name the new substance formed. Write the chemical equation.
  6. A metal Y forms a salt YSO4. When the aqueous solution of the salt YSO4 is treated with NaOH, a blue precipitate is formed. Metal Y is used in making electrical wires and alloys like brass. What is the metal Y. Identify the blue precipitate. Write the chemical equation.


Atomic Weight:

H = 1 U  C = 12 U  N = 14 U  O = 16 U  Na = 23 U  Mg = 24 U  Al = 27 U  Cl = 35.5U  K = 39 U  Ca = 40 U  Fe = 56 U

  1.  Al + Fe2O3 —> Al2O3 + Fe. Calculate the amount of Aluminium required to form 616g of iron.
  2. Calculate the volume of Hydrogen gas liberated when 276 g of sodium reacts with water.
  3. Calculate the number of molecules of CO2 liberated when 50g of CaCO3 is treated with 7.3g of HCl. Which is the limiting agent?
  4.  92g of Na contains ____ number of Na atoms.
  5.  32g of oxygen gas occupies ____volume.
  6. 47g of impure Al2O3 is reduced electrolytically to give Aluminium and Oxygen. Calculate the amount of Aluminium formed.
  7. C2H6 + O2 —-> CO2 + H2O. 60 litres of ethane (C2H6) is mixed with 448 litres of oxygen (O2) and ignited. Calculate the volume of CO2 formed during this reaction.
  8. How many moles of water are required to be dissociated to produce oxygen gas which is sufficent to form 800g of MgO by burning Mg with oxygen.
  9. Calculate the amount of KCl formed when 12.25g of KClO3 is decomposed.
  10. What is the amount of NH3 formed when 14g of N2 reacts with 6g of H2.