Which of the following processes is spontaneous? This question often arises in the field of chemistry and thermodynamics, where the spontaneity of a process is a crucial factor in understanding the direction and feasibility of chemical reactions. In this article, we will explore the concept of spontaneity and discuss various processes to determine which one is spontaneous.
Spontaneity refers to the ability of a process to occur without any external influence. In thermodynamics, the spontaneity of a process is determined by the change in Gibbs free energy (ΔG). If ΔG is negative, the process is spontaneous; if ΔG is positive, the process is non-spontaneous; and if ΔG is zero, the process is at equilibrium.
Let’s consider the following processes and analyze their spontaneity:
1.
Reaction A: 2H2(g) + O2(g) → 2H2O(g)
This reaction represents the formation of water from hydrogen and oxygen gases. The ΔG for this reaction is negative, indicating that it is spontaneous. This is because the reaction releases energy in the form of heat, making it a favorable process.
2.
Reaction B: N2(g) + 3H2(g) → 2NH3(g)
This reaction represents the formation of ammonia from nitrogen and hydrogen gases. The ΔG for this reaction is also negative, indicating that it is spontaneous. This process is known as the Haber process and is widely used in the industrial production of ammonia.
3.
Reaction C: CaCO3(s) → CaO(s) + CO2(g)
This reaction represents the decomposition of calcium carbonate into calcium oxide and carbon dioxide. The ΔG for this reaction is positive, indicating that it is non-spontaneous under standard conditions. However, this reaction can be driven to occur by providing heat, making it a reversible process.
4.
Reaction D: 2H2O(l) → 2H2(g) + O2(g)
This reaction represents the decomposition of water into hydrogen and oxygen gases. The ΔG for this reaction is positive, indicating that it is non-spontaneous under standard conditions. This process requires energy input in the form of electricity or heat to proceed.
In conclusion, among the given processes, Reaction A (2H2(g) + O2(g) → 2H2O(g)) and Reaction B (N2(g) + 3H2(g) → 2NH3(g)) are spontaneous. These reactions release energy and are favorable under standard conditions. On the other hand, Reaction C (CaCO3(s) → CaO(s) + CO2(g)) and Reaction D (2H2O(l) → 2H2(g) + O2(g)) are non-spontaneous under standard conditions and require external energy input to proceed.
