Which of the following aqueous solutions has a Cl– concentration of 2 m at 25°C?
271 g of HgCl2 in 55 mol of H2O
271 g of HgCl2 in 22.5 mol of H2O
53 g of NH4Cl in 55 mol of H2O
53 g of NH4Cl in 22.5 mol of H2O.
D. Pure water has a concentration of 55 M and density of 1 kg/L. 55 moles of water represent 1 L (1 kg) and 22.5 moles of water represent 0.5 L (0.5 kg). HgCl2 demonstrates poor water solubility and will dissociate little. Therefore, 1 mol of HgCl2 placed in either water 1 kg or 0.5 kg of water will not achieve a 2 m Cl– solution, eliminating choices A and B. NH4Cl is water soluble and has a molecular weight of 53 g/mol. Choice C is a 1 m NH4Cl (1 m Cl–) solution and Choice D is a 2 m NH4Cl (2 m Cl–) solution.
No equation. Conceptual
The Attempt at a Solution
I understand that we are looking for the answer that has a concentration of 2 M for chlorine and I understand that A and B are wrong because that compound is insoluble in water but what I don't understand is why we get a 2 molar solution when we add it to half a liter of water vs getting a 1 molar solution when we add it to 1 liter of water