Number of molecules and moles in 2.8375 litre of O2 at STP.
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Approach Solution - 1
Step 1: Calculate the Number of Moles of O2
At STP, 1 mole of a gas occupies 22.7 liters. The given volume of O2 is 2.8375 liters. The number of moles is calculated as:
\[ n_{\text{O}_2} = \frac{\text{Volume of O}_2}{22.7} \]
Substitute the given values:
\[ n_{\text{O}_2} = \frac{2.8375}{22.7} = 0.125 \, \text{moles} \]
Step 2: Calculate the Number of Molecules of O2
The number of molecules of O2 is given by:
\[ \text{Molecules of O}_2 = n_{\text{O}_2} \cdot N_A \]
Where \( N_A = 6.022 \times 10^{23} \, \text{mol}^{-1} \) (Avogadro’s number).
Substitute the values:
\[ \text{Molecules of O}_2 = 0.125 \cdot 6.022 \times 10^{23} = 7.527 \times 10^{22} \, \text{molecules} \]
Final Answer:
- The number of moles of O2 is 0.125 mol.
- The number of molecules of O2 is 7.527 × 1022.
Approach Solution -2
At STP, one mole of any gas occupies 22.4 liters. For the given volume of oxygen gas (2.8375 liters):
Step 1: Calculate the Number of Moles of O2
The number of moles is calculated as:
\[ \text{Number of moles of O}_2 = \frac{2.8375 \, \text{L}}{22.4 \, \text{L/mol}} = 0.125 \, \text{mol} \]
Step 2: Calculate the Number of Molecules of O2
Using Avogadro’s number (\( 6.022 \times 10^{23} \, \text{molecules/mol} \)):
\[ \text{Number of molecules of O}_2 = 0.125 \, \text{mol} \times 6.022 \times 10^{23} \, \text{molecules/mol} \]
\[ \text{Number of molecules of O}_2 = 7.527 \times 10^{22} \, \text{molecules} \]
Final Answer:
- Number of moles of O2: 0.125 mol
- Number of molecules of O2: \( 7.527 \times 10^{22} \, \text{molecules} \)
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Liquid State:
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- These forces are weaker than solids but stronger than that of gases.
- There is much space in between the molecules of liquids which makes their flowing ability easy.
Gaseous State:
- In this state of matter, distances between the molecules are large (intermolecular distance is in the range of 10-7-10-5 cm.
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