Final answer:
The question is incomplete and needs specification of the chloride compound to accurately determine the number of moles of chloride ions. Using calcium chloride (CaCl₂) as an example, one would need to consider there are 2 chloride ions per formula unit. In a 0.200-M solution of CaCl₂, 250 mL would contain 5.549 grams of CaCl₂, which corresponds to 0.0500 mol of the compound, and thus 0.100 mol of chloride ions.
Step-by-step explanation:
To determine the number of moles of chloride ions, we need further context as the question 'How many moles of chloride ions are in 0.2550?' is incomplete. Assuming this refers to 0.2550 moles of a chloride compound (since no units are specified), the number of chloride ions would depend on the particular compound in question. For instance, if the compound was NaCl, there would be 1 mole of chloride ions for every mole of NaCl. However, if the compound was CaCl₂, each mole would contain 2 moles of chloride ions due to the two chloride ions in each formula unit.
If we take the CaCl₂ example provided, and a 0.200 M solution, we can calculate the mass of CaCl₂ in the solution using its molar mass of 110.98 g/mol. First, convert 250.0 mL to liters (0.250 L), then multiply by the concentration (0.200 mol/L) to find the moles of CaCl₂ in solution: 0.0500 mol. Multiplied by the molar mass, we get 5.549 grams of CaCl₂.
For NaCl, the process involves converting the grams to moles using the molar mass, then doubling the result because NaCl dissociates into two ions per formula unit.