Question

Calculate the kinetic energy (in joules) of a mole of water molecules traveling at 11.7 m/s.

Answer 1

Answer:

$k=1.23J$

Explanation:

1. The equation to calculate the kinetic energy is:

$k=\frac{mv^{2} }{2}$ (Eq.1)

where, m=mass, v=velocity, k=kinetic energy

2. Find the mass of one mole of water, $H_{2}O$:

Atomic weight of H = 1$\frac{g}{mol}$

Atomic weight of O = 16$\frac{g}{mol}$

Molecular weight of $H_{2}O$ = (2*1) + 16

Molecular weight of $H_{2}O$ = 18$\frac{g}{mol}$

3. Convert the mass of $H_{2}O$ from g to Kg:

$18g*\frac{1Kg}{1000g}=0.018Kg$

3. Replace quantities in Eq.1:

$k=\frac{0.018g*(11.7\frac{m}{s})^{2}}{2}$

$k=1.23J$

Answer 2

Atomic mass of hydrogen= 1 u
Atomic mass of oxygen = 16 u
Molecular mass of water=1*2+16*1
=18 u
Mass of 1 mole of water= 18 g=0.018 kg
KE=1/2mv²
=1/2*0.018*11.7²
=1.23 J (approx.)