In which sample is the average kinetic energy of the particles greatest?

(1) 10. mL of HCl(aq) at 25°C

(2) 15 mL of HCl(aq) at 20.°C

(3) 10. mL of H2O(l) at 35°C

(4) 15 mL of H2O(l) at 30.°C

Verified Answer :

The question asks about the average kinetic energy, so it is related only to temperature. Then the answer is (3) with the highest temperature.

Answer: The correct answer is option 3.

Explanation: Average kinetic energy is defined as the energy of motion of the particles of a system. It is a measure of Kelvin Temperature.

Mathematically,

\(K=\frac{3}{2}\frac{R}{N_A}T\)

where,

K = kinetic energy of the molecules measured in joules.

R = Gas constant = \(8.314Jmol^{-1}K^{-1}\)

\(N_A\) = Avogadro's number = \(6.022\times 10^{23}atoms/mol\)

T = Temperature in kelvins.

Kinetic energy is directly proportional to the temperature of the system.

\(\text{Kinetic energy}\propto \text{Temperature}\)

More the temperature, more will be the kinetic energy of the molecules.

Hence, the correct answer is Option 3.