Question

Calculate the number of moles and molecules present in the following: (i) 0.04g of methane

Answer 1

Answer:

Number of moles = 0.0025 moles

Number of molecules = 0.015 * 10²³ molecules

Explanation:

$\diamond$ We know that,

Number of moles = $\dfrac{Given \ Mass}{Molar \ Mass}$

Number of moles = $\dfrac{Number \ of \ molecules }{Avogadro \ Number}$

$\diamond$ Given that,

Given mass = 0.04g

Molar mass of CH₄ = 12 + 4 = 16g

Avogadro Number = 6.022 * 10²³

$\diamond$ Substituting these values we get,

Number of moles = $\dfrac{0.04}{16} = 0.0025 \ moles$

$\diamond$ Substituting the value of number of moles and avogadro number we get,

0.0025 = $\dfrac{Number \ of \ molecules }{6.022 * 10^{23}}$

Number of molecules = 0.0025 * 6.022 * 10²³

Number of molecules = 0.015 * 10²³