Final answer:
Using the density of water in percent error calculations depends on the experiment's context. It is necessary when water's properties are integral to the experiment, such as when determining the density of a substance via displacement. The percent error formula itself does not include density unless it is relevant to the measured values.
Step-by-step explanation:
The necessity of using the density of water in calculations for the percent error is C) It depends on the specific experiment or context. When performing experiments that involve calculations of mass, volume, or concentration where water serves as a medium or reactant, its density may play a crucial role. For example, when calculating the concentration of ethanol in a solution, knowing the density of water allows you to determine the mass of water, if the volume is known, which may be necessary to calculate the solution's total mass and thereby the mass percentage of ethanol. However, if the experiment or measurement is unrelated to the properties of water, then the density of water would not be relevant.
The percent error calculation itself, which compares the experimental value to a known or accepted value to express the accuracy of a measurement, does not inherently require the density of water unless that density is related to either the experimental value or the known value. For instance, an experimental determination of density using water displacement would involve the density of water since it is essential for deriving the density of the object being studied.