What are the molecular weights of the gases with the following densities: (a) 1.342 g/L at STP

Verified step by step guidance

1. Step 1: Recall that the molar volume of a gas at standard temperature and pressure (STP) is 22.4 L/mol. This is a standard value that you can use in calculations involving gases at STP.
2. Step 2: The density of a gas at STP is given by the formula: Density = Molecular weight / Molar volume. In this case, we know the density and the molar volume, and we need to find the molecular weight.
3. Step 3: Rearrange the formula to solve for the molecular weight: Molecular weight = Density * Molar volume.
4. Step 4: Substitute the given density (1.342 g/L) and the molar volume (22.4 L/mol) into the formula: Molecular weight = 1.342 g/L * 22.4 L/mol.
5. Step 5: Calculate the molecular weight. The units of grams per liter (g/L) and liters per mole (L/mol) will cancel out, leaving the molecular weight in grams per mole (g/mol).

Key Concepts

Molecular Weight

Molecular weight, or molar mass, is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic weights of all atoms in a molecule. Understanding molecular weight is essential for converting between mass and moles, which is crucial in stoichiometric calculations and gas law applications.

Density of Gases

Density is defined as mass per unit volume, and for gases, it is often expressed in grams per liter (g/L). The density of a gas can vary with temperature and pressure, but at standard temperature and pressure (STP), it can be used to determine the molecular weight of the gas using the ideal gas law. This relationship is vital for solving problems involving gas densities.

Ideal Gas Law

The ideal gas law is a fundamental equation in chemistry that relates the pressure, volume, temperature, and number of moles of an ideal gas. It is expressed as PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature in Kelvin. This law allows for the calculation of various properties of gases, including their molecular weights when combined with density.