Chemical Equations (VSAQs)

Physical Science | 2. Chemical Equations – VSAQs:
Welcome to VSAQs in Chapter 2: Chemical Equations. This page contains the most important VSAQs in this chapter. Aim to secure top marks in your exams by understanding these clear and straightforward Very Short Answer Questions.

VSAQ-1 : Balance the following chemical equation.
Al+Fe2O3→Al2O3+Fe

$$2\text{Al} + \text{Fe}_2\text{O}_3 \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}$$

VSAQ-2 : Balance the following chemical equation.

Na+H2O→NaOH+H2

Balanced Chemical Equation:

  1. Unbalanced Equation:
    $$\text{Na} + \text{H}_2\text{O} \rightarrow \text{NaOH} + \text{H}_2$$
  2. Balanced Equation:
    • $$2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2$$
    • In this reaction, 2 atoms of sodium (Na) react with 2 molecules of water (H2​O) to form 2 molecules of sodium hydroxide (NaOH) and 1 molecule of hydrogen gas (H2​).

VSAQ-3 : Na2SO4+BaCl2→BaSO4+NaCl. Do the atoms of each element on the left side equal to the atom of the element on the right side of the equation?

Equation Balancing:

  1. Original Equation:
    $$\text{Na}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + \text{NaCl}$$
  2. Balanced Equation:
    • $$\text{Na}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + 2\text{NaCl}$$
    • In the balanced equation, atoms of each element on the left side are now equal to the atoms of the same element on the right side.

VSAQ-4 : Mention the chemical equation of reaction between the Mg and O2 and write its physical state of reactants and products.

Chemical Equation and Physical States:

  1. Equation:
    $$2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$$
  2. Physical States of Reactants and Products:
    • Magnesium (Mg): Solid
    • Oxygen (O2): Gas
    • Magnesium Oxide (MgO): Solid

VSAQ-5 : How do we know that a chemical reaction has taken place?

Indicators of Chemical Reactions:

  1. Change in State and Color: Observable when substances transform from one state (solid, liquid, gas) to another or exhibit a noticeable color change.
  2. Change in Temperature: A significant increase or decrease in temperature during the reaction, indicating energy changes.
  3. Formation of Precipitate: Occurs when two solutions mix and an insoluble solid (precipitate) forms.
  4. Liberation of Gas: The production of gas bubbles or a noticeable release of gas during the reaction.

VSAQ-6 : If you keep an iron piece in solid state CuSO4 crystals, does it get any reaction? Guess the reason.

Chemical Interaction:

  1. Situation: Iron piece placed in solid-state CuSO4 crystals.
  2. Reaction Occurrence: Typically, no reaction occurs.
  3. Reason for Non-Reactivity:
    • In solid CuSO4 crystals, copper ions (Cu²⁺) and sulfate ions (SO4²⁻) are not freely available as separate entities.
    • Chemical reactions generally occur when ions are in solution and can interact with other substances.
    • In an aqueous solution of CuSO4, the Cu²⁺ ions are in a form that allows iron to displace copper in a redox reaction.
    • However, in the solid state, the ions are not as accessible for such reactions.