Question

Explain mole concept​

Answer 1

Explanation

A mole ( symbol mol ) is defined as the amount of substance that contains as many atoms , molecules, ions electrons or any other elementary entities as there are carbon atoms in exactly 12gm of ¹²C

The Number of atoms in 12 gm of carbon is called Avogadro's number

$\boxed{ \rm \: Avogardo \: no \: (N_A) = 6.023 \times 10 {}^{23} }$

One atomic mass unit ( amu)

$\rm \: \frac{1}{N_A} = \frac{1}{6.023 \times 10 {}^{23} } gm = 1.66 \times 10 {}^{ - 24} \: gm$

$\rm \: = 1 .66 \times {10}^{ - 27} \: kg$

The number of moles of a substance can be calculated by various means depending on data available as follows

$\to \rm \: Number \: of \: moles \: of \: atom \: \\ = \rm\frac{weight \: in \: gm}{Atomic \: mass}$

$\rm \: \to \: number \: of \: moles \: of \: molecules \\ \\ = \rm\frac{weight \: in \: gm}{molecular \: mass}$

$\rm \: \to \: 1 \: moles \: of \: any \: gas \: at \: STP \: occupies \: 22.7 \: litre$

$\rm \: \to \: 1 \: moles \: of \: any \: gas \: at \:NTP \: occupies \: 22.4 \: litre$

$\to \rm \: number \: of \: moles \: of \: gases \\ = \rm\frac{volume \: at \: STP}{std. \: molar \: volume \: at \: STP } \\ = \rm\frac{volume \: at \: STP}{22.7}$

$\rm \: number \: of \: moles \: of \: gases \\ = \rm\frac{volume \: at \: NTP}{std. \: molar \: volume \: at \: NTP } \\ = \rm\frac{volume \: at \: NTP}{22.4}$

$\to\rm \: number \: of \: mole \: of \: particles \: \\ = \rm \frac{number \: of \: particles}{avogadro \: number}$

$\rm \: \to \: if \: volume \: of \: a \: gas \: is \: given \: along \: with \: temperature(t) \: \: and \: pressure(p \\ \rm \:$

$\rm \: use \: \: \: n = \frac{PV}{RT} \\ \rm \: where \: R\: = 0.0821 \: lit -\: atm \: mol \: - k {}^{ - 1}$