How many moles of sodium chloride are there in 250 mL of a 1.20 M sodium chloride solution?

Question

BlackTom AI · Accepted Answer

First, restate the problem in my own words to ensure understanding: we need the number of moles of NaCl in a 250 mL sample of a 1.20 M solution. The key relation is moles = molarity × volume (in liters).
Option A: 2.4. If you multiplied 1.20 M by 2.0 L you’d get 2.4 moles, but the volume here is only 0.250 L, not 2.0 L, so 2.4 is far too large for the given volume.
Option B: 0.60. This would correspond to a volume of 0.50 L (since 1.20 M × 0.50 L = 0.60 mol). Our volume is 0.250 L, so this value is not correct for the stated volume.
Option C: 0.30. Computing directly: moles = 1.20 M × 0.250 L = 0.30 mol. This matches the product of the given molarity and volume, so this is the correct calculation for the provided data.
Option D: 1.2. This would require a volume of 1.0 L (since 1.20 M × 1.0 L = 1.2 mol). Since our volume is only a quarter of a liter, this value is inconsistent with the given conditions.
To summarize the conceptual check: you need to convert the 250 mL to liters and multiply by the molarity. 250 mL = 0.250 L, and 0.250 L × 1.20 mol/L yields 0.30 mol. Any result that deviates from this product either uses an incorrect volume or an incorrect units-to-moles conversion, which signals a misapplication of the formula.
A common pitfall is confusing volume units or neglecting to convert milliliters to liters before multiplying by molarity; always ensure the volume is in liters when using molarity units (mol/L).

CHE 1V_SS1 2025 Final Exam_SS1_2025_Proctored

How many moles of sodium chloride are there in 250 mL of a 1.20 M sodium chloride solution?

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