Ammonium Chloride is a white solid. When heated to 325 degrees C, it gives a vapor that is a mixture of ammonia and hydrogen chloride.

Suppose someone contends that the vapor consists of NH4Cl molecules rather than a mixture of NH3 and HCl. Could you decide between these alternatvie views on the basis of gas-density measurements? Explain.

To decide between the two alternative views (NH4Cl molecules vs. a mixture of NH3 and HCl) on the basis of gas-density measurements, we need to understand the concept of molar mass and the ideal gas law.

First, let's take a look at the molar masses of the substances involved:

- The molar mass of NH4Cl (ammonium chloride) is calculated by adding up the atomic masses of nitrogen (N), hydrogen (H), and chlorine (Cl). Mass(N) + 4 * Mass(H) + Mass(Cl) = 14.01 g/mol + 4 * 1.01 g/mol + 35.45 g/mol = 53.49 g/mol.
- The molar mass of NH3 (ammonia) is calculated by adding up the atomic masses of nitrogen (N) and hydrogen (H). Mass(N) + 3 * Mass(H) = 14.01 g/mol + 3 * 1.01 g/mol = 17.03 g/mol.
- The molar mass of HCl (hydrogen chloride) is calculated by adding up the atomic masses of hydrogen (H) and chlorine (Cl). Mass(H) + Mass(Cl) = 1.01 g/mol + 35.45 g/mol = 36.46 g/mol.

Now, let's examine the ideal gas law, which states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

If we assume that the vapor consists of NH4Cl molecules, we have to consider the molar mass of NH4Cl as 53.49 g/mol. On the other hand, if the vapor is a mixture of NH3 and HCl, we need to calculate the average molar mass based on the relative proportions of NH3 and HCl in the mixture.

By measuring the density of the vapor, we can determine the molar mass using the equation:
molar mass = (density * R) / (P / T)

If the measured molar mass matches the calculated molar mass of NH4Cl (53.49 g/mol), it would support the contention that the vapor consists of NH4Cl molecules. However, if the measured molar mass is different and corresponds to the average molar mass of NH3 and HCl, it would favor the viewpoint that the vapor is a mixture of NH3 and HCl.

In conclusion, by conducting gas-density measurements and comparing the measured molar mass with the calculated molar mass of NH4Cl, we can make an inference about the composition of the vapor, determining whether it consists of NH4Cl molecules or a mixture of NH3 and HCl.