A student performs a gravimetric analysis experiment to determine the mass percent of \(\text{Cl}\) in an unknown soluble salt mixture. The student dissolves a \(0.500 \text{ g}\) sample of the mixture in distilled water and adds an excess of \(\text{AgNO}_3\text{(aq)}\) to precipitate \(\text{AgCl(s)}\). The precipitate is collected by filtration and weighed. Which of the following experimental errors would cause the calculated mass percent of \(\text{Cl}\) in the mixture to be higher than the actual mass percent?