Final answer:
To determine the molarity of a stock solution of p-nitrophenol, you would use the dilution equation M1V1 = M2V2. However, without specific initial concentration data (M1), we cannot calculate the stock solution's molarity.
Step-by-step explanation:
To calculate the molarity of the stock solution of p-nitrophenol, we need to understand the concept of dilution and the relationship between the concentration of the original stock solution and the concentration of the diluted solution. The molarity (M) is the number of moles of solute per liter of solution. To find the molarity of the stock solution, we typically use the dilution equation M1V1 = M2V2, where M1 is the molarity of the stock solution, V1 is the volume of the stock solution, M2 is the molarity of the diluted solution, and V2 is the final volume of the solution.
Given that the volume of the solution is increased from 0.85 L to 1.80 L and the diluted solution's concentration is less than one-half of 5 M, we employ the dilution formula to compute the molarity of the stock solution. However, the exact initial concentration is not provided in the given information, so we cannot calculate the exact molarity without additional data.
If for instance, the molarity after dilution (M2) was known to be 0.310 M after the stock solution was diluted tenfold, then by rearranging the dilution equation M1 = (M2V2) / V1, substituting the known values, and solving for M1 we could determine the molarity.