Question

The maximum number of molecules is present in

• A. 10 g of $O_2$ gas
• B. 15 L of $H_2$ gas at S.T.P
• C. 5 L of $N_2$ gas at S.T.P
• D. 0.5 g of $H_2$ gas

Hint:

At Standard Temperature and Pressure (S.T.P), specific conditions define the maximum number of molecules present in a given volume of gas

Answer 1

The Correct Option is B

Calculate number of molecules (n) for each of the given options, 

In 15 L of H₂ gas at STP,

n = \(\frac{6.023 \times 10^{23}}{22.4} \times 15 = 4.033 \times 10^{23}\)

In 0.5 g of H₂ gas,

n = \(\frac{6.023 \times 10^{23} \times 0.5}{2} = 1.505 \times 10^{23}\)

In 5 L of N₂ gas at STP,

n = \(\frac{6.023 \times 10^{23} \times 5}{22.4} = 1.344 \times 10^{23}\)

In 10 g of O₂ gas,

n = \(\frac{6.023 \times 10^{23} \times 10}{32} = 1.882 \times 10^{23}\)

The maximum number of molecules are present in 15 L of H₂ gas at STP, hence option B is correct. 

Discover More From Concept: Stoichiometry 

Answer 2

The Correct Answer is (B)

Real Life Applications

The real-life applications of the abundance of molecules in 15 L of H2 gas at STP are: 
1. Gas Cylinders: The vast number of molecules, approximately 4.031 x 10^23, in 15 L of hydrogen gas at STP makes it ideal for gas cylinders. This storage capacity allows for the efficient utilization of hydrogen in various applications, including fuel cells and welding processes.
2. Fuel Cells: Leveraging this substantial molecule count, fuel cells efficiently produce electricity by combining hydrogen and oxygen gases. The impressive storage capability of 15 L of hydrogen gas ensures prolonged power generation. 
3. Welding: The immense molecule count makes hydrogen gas a preferred choice for welding due to its ability to produce intensely hot flames. With 15 L of hydrogen gas at STP, sizable objects can be effectively welded.

Question can also be asked as

1. What is the maximum number of molecules of hydrogen gas that can be present in 15 liters of gas at STP? 
2. How many molecules of hydrogen gas are present in 15 liters of gas at STP?
3. What is the relationship between the number of molecules of a gas and its volume at STP? 
4. How can you calculate the number of molecules of a gas at STP?

Answer 3

The Correct Answer is (B)

At Standard Temperature and Pressure (S.T.P), specific conditions define the maximum number of molecules present in a given volume of gas. 

• S.T.P refers to a set of standardized conditions used for comparing and measuring gases.
• It is defined as a temperature of 273.15 Kelvin (0 degrees Celsius) and a pressure of 1 atmosphere (atm).

Avogadro's Law

• Avogadro's law states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules.
• This law allows us to determine the number of molecules based on the volume and conditions of the gas.

Ideal Gas Law

• The ideal gas law combines several gas laws, including Avogadro's law, into a single equation: PV = nRT.
• P represents pressure, V represents volume, n represents the number of moles, R is the ideal gas constant, and T represents temperature.

Calculating the Number of Molecules

• To determine the number of molecules in a given volume of gas, we need to convert the volume to the number of moles using the ideal gas law.
• At S.T.P., 1 mole of any gas occupies a volume of 22.4 litres.

Calculation Example

• Given that we have 15 liters of H2 gas at S.T.P, we can calculate the number of moles using the conversion factor:
• 15 liters / 22.4 liters/mole = 0.67 moles of H2 gas.
• Since 1 mole of any gas contains approximately 6.022 x 10²³ molecules (Avogadro's number), we can multiply the number of moles by Avogadro's number to determine the maximum number of molecules:
• 0.67 moles x 6.022 x 10²³ molecules/mole = 4.03 x 10²³ molecules of H2 gas.

Therefore, in 15 liters of H2 gas at S.T.P., the maximum number of molecules is approximately 4.03 x 10²³.

Check Out:

Related Concepts
Three States of Matter	Imperfections in Solids	Crystal Lattices and Unit Cells
Properties of Matter	Point defects	Packing Efficiency
Electron Vacancy	Metal Deficiency Defect	Frenkel Defect