Chemical Reactions and Equations

For survival, life requires energy. The food we eat provides us with this energy. Through the process of digestion, the food molecules are reduced to simpler molecules like glucose. When these materials combine with the oxygen already present in our body cells, carbon dioxide and water are produced, along with a certain amount of energy …

Why is respiration considered to be an exothermic reaction? Read More »

When energy from the surroundings is absorbed in heat from the surroundings, an endothermic reaction takes place (For example, Photosynthesis, melting of ice, evaporation). On the other side, an exothermic reaction involves the release of energy from the system into the surroundings (Examples: Explosions, concrete settings, nuclear fission and fusion).

(i) 2KBr + BaI2 → 2KI + BaBr2 (Double Displacement Reaction) (ii) ZnCO3 → ZnO + CO2 (Decomposition Reaction) (iii) H2 + Cl2 → 2HCl (Combination Reaction) (iv) Mg + 2HCl → MgCl2 + H2 (Displacement Reaction)

2Ca(OH)2 + 2CO2 → 2CaCO3 + 2H2O Zn + 2AgNO3 → Zn(NO3)2 + 2Ag 2Al + 3CuCl2 → 2AlCl3 + 3Cu BaCl2 + K2SO4 → BaSO4 + 2KCl

(a) 2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O (b) 2NaOH + H2SO4 → Na2SO4 + 2H2O (c) NaCl + AgNO3 → AgCl + NaNO3 (d) BaCl2 + H2SO4 → BaSO4 + 2HCl

(a) Unbalanced: H2 + N2 → NH3 Balanced: 3H2 + N2 → 2NH3 (b) Unbalanced: H2S + O2 → H2O + SO2 Balanced: 2H2S + 3O2 → 2H2O + 2SO2 (c) Unbalanced: BaCl2 + Al2(SO4)3 → AlCl3 + BaSO4 Balanced: 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4 (d) Unbalanced: K + H2O → KOH + …

Translate the following statements into chemical equations and balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in the air to give water and sulphur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give Aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and Hydrogen gas. Read More »

When the number of distinct atoms on the reactant and product sides of an equation is equal, the equation is said to be balanced. Chemical equations must be balanced for the reaction to follow the Law of Conservation of Mass. Chemical equation balancing is a trial-and-error process with no defined approach.

Hydrogen gas and Iron chloride are produced. The iron fillings displace the chlorine from hydrogen chloride to cause the reaction that follows. 2HCl + Fe → FeCl2 + H2

The answer is (iv). Displacement reaction. Reason: To create Aluminium oxide, oxygen from ferrous oxide is transferred to Aluminium metal. Aluminium is a more reactive metal than Fe in this reaction. Al will therefore remove Fe from its oxide. One of the elements displaces another in a chemical process known as a displacement reaction. More …

Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a (i)Combination reaction (ii)Double displacement reaction (iii)Decomposition reaction (iv)Displacement reaction Read More »

(i) (a) and (b) Explanation: (a) Because oxygen is being taken out, and (b) Because the elemental Carbon is being given more oxygen taken out of Lead.