Question:

When 600 mL of 0.2 M HNO3 is mixed with 400 mL of 0.1 M NaOH solution in a flask, the rise in temperature of the flask is ________ × 10–2 °C.
(Enthalpy of neutralisation = 57 kJ mol–1 and Specific heat of water = 4.2 JK–1 g–1)
(Neglect heat capacity of flask)

Updated On: Nov 6, 2024
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Correct Answer: 54

Solution and Explanation

H++OHH2O\text{H}^+ + \text{OH}^- \rightarrow \text{H}_2\text{O}
m moles 120 40 – 80 – 40

Heat liberated from reaction
= 40 × 10–3× 57 × 103 J …(1)

Heat gained by solution = mCΔTmC\Delta T
Mass of solution m=V×d=1000×1=1000gm = V × d = 1000 × 1 = 1000 g
Heat gained by solution =1000×4.2×ΔT(2)= 1000 × 4.2 × ΔT …(2)
From eq (1) and eq (2)
Heat liberated = Heat gained
40×103 ×57×103 =1000×4.2×ΔT40 × 10–3 × 57 × 103 = 1000 × 4.2 × ΔT
ΔT=54×ΔT = 54 × 10–2 °C°C
ΔT=54°CΔT = 54°C (Rounded off to the nearest integer)
So, the answer is 54°C.

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Concepts Used:

Solutions

A solution is a homogeneous mixture of two or more components in which the particle size is smaller than 1 nm.

For example, salt and sugar is a good illustration of a solution. A solution can be categorized into several components.

Types of Solutions:

The solutions can be classified into three types:

  • Solid Solutions - In these solutions, the solvent is in a Solid-state.
  • Liquid Solutions- In these solutions, the solvent is in a Liquid state.
  • Gaseous Solutions - In these solutions, the solvent is in a Gaseous state.

On the basis of the amount of solute dissolved in a solvent, solutions are divided into the following types:

  1. Unsaturated Solution- A solution in which more solute can be dissolved without raising the temperature of the solution is known as an unsaturated solution.
  2. Saturated Solution- A solution in which no solute can be dissolved after reaching a certain amount of temperature is known as an unsaturated saturated solution.
  3. Supersaturated Solution- A solution that contains more solute than the maximum amount at a certain temperature is known as a supersaturated solution.