Final answer:
At STP, the density of HCl gas is 1.63 g/L. This is calculated using HCl's molar mass (36.46 g/mol) and the molar volume of an ideal gas at STP (22.4 L/mol).
Step-by-step explanation:
The question asks for the density of HCl gas at standard temperature and pressure (STP), where STP is defined as 0°C (273 K) and 1 atm pressure. To calculate the density of HCl at STP, we use the molar mass of HCl, which is approximately 36.46 g/mol, along with the fact that one mole of any ideal gas occupies 22.4 liters at STP. The density (d) can be found using the formula d = molar mass/volume. For HCl at STP:
d = 36.46 g/mol / 22.4 L/mol
= 1.63 g/L
This density is slightly less than that of ammonia at STP, which makes sense because HCl gas has a lower molar mass compared to ammonia. Understanding gas density is essential in chemistry for various applications including reactions involving gases and gas stoichiometry.