Question

STPতে 112 mL আয়তনের ভর 0.22g।ঐ নমুনায় কটি অণু আছে গ্যাসটির মোলার ভর কত​

Answer 1

Answer:প্রশ্ন:- অ্যাভোগাড্রো সংখ্যা কাকে বলে ? এর মান কত ?

উত্তর:- এক গ্রাম-অণু পরিমাণ যে-কোনো পদার্থে সমান সংখ্যক অণু থাকে । এই সংখ্যাকে অ্যাভোগাড্রো সংখ্যা বলে । অ্যাভোগাড্রো সংখ্যার মান : 6.023 x 1023 ।

Explanation:

Answer 2

Given:

In STP,

The mass of an unknown sample of gas, m = 0.22 g

The volume of the unknown gas, V = 112 ml = $\frac{112}{1000} \:L = 0.112 \:L$

To find:

(i). How many molecules are there in the sample?

(ii) What is the molar mass of the gas?

Solution:

(i). Finding the moles in the given sample of gas:

We know,

At S.T.P → 1 mole of gas contains a volume of 22.4 L

and

1 mole of gas = 6.022 × 10²³ molecules/atoms/ions

We have a formula as:

$\boxed{\bold{No.\:of\:moles, \:n = \frac{Volume\:(in\:litres)}{Volume\:of\:a \:gas\:at\:S.T.P} }}$

So, by substituting the values of the volumes, we get

n = $\frac{0.112}{22.4} = 5\times 10^-^3\:moles$

Now,

If 1 mole of a gas = 6.022 × 10²³ molecules

Then,

$5\times 10^-^3\:moles$ of the given sample is,

= $5\times 10^-^3\times 6.022 \times 10^2^3$

= $30.11\times 10^2^0$

= $30.11\times 10^2^0\times \frac{10}{10}$

= $\bold{3.011\times 10^2^1\:molecules}$

Thus, there are $\underline{3.011\times 10^2^1\:molecules}$ in the sample.

(ii). Finding the molar mass of the given sample of gas:

We have a formula as:

$\boxed{\bold{No.\:of\: moles = \frac{Mass\:of\:the\:gas}{Molar\:mass\:of \:the\:gas}\:i.e., n = \frac{m}{M} }}$

Now, substituting the value if n = $5\times 10^-^3\:moles$ & m = 0.22 g in the formula above,

$5\times 10^-^3= \frac{0.22}{M}$

$\implies M = \frac{0.22}{5\times 10^-^3}$

$\implies M = \frac{0.22\times 10^3}{5}$

$\implies M = 0.044\times 10^3$

$\implies \bold{M = 44 \:gm/mole}$

Thus, the molar mass of the given sample of gas is $\underline{44\: g/mol}$ .

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