Class 10 Science: Chemical Reactions & Equations

1. Combination Reaction

Burning of Magnesium Ribbon

$$2Mg(s) + O_2(g) \xrightarrow{\Delta} 2MgO(s)$$

When a magnesium ribbon is heated in the presence of oxygen, it burns with a dazzling white flame to form a white powder called magnesium oxide. This is a combination reaction where two reactants combine to form a single product.

2. Displacement Reaction

Iron Nails in Copper Sulphate

$$Fe(s) + CuSO_4(aq) \rightarrow FeSO_4(aq) + Cu(s)$$

Iron is more reactive than copper. When an iron nail is dipped in a blue copper sulphate solution, iron displaces copper from the solution. The blue colour of the solution fades to light green (ferrous sulphate), and a brown coating of copper deposits on the nail.

3. Double Displacement

Formation of Barium Sulphate

$$Na_2SO_4(aq) + BaCl_2(aq) \rightarrow BaSO_4(s)\downarrow + 2NaCl(aq)$$

When aqueous solutions of sodium sulphate and barium chloride are mixed, a mutual exchange of ions takes place. This results in the formation of a white, insoluble solid called a precipitate (Barium Sulphate).