(a) After the label fell off a bottle containing a clear liquid believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0-mL portion of the liquid had a mass of 21.95 g. A chemistry handbook lists the density of benzene at 15 °C as 0.8787 g/mL. Is the calculated density in agreement with the tabulated value?

Key Concepts

Density

Density is defined as the mass of a substance divided by its volume, typically expressed in grams per milliliter (g/mL) for liquids. It is a physical property that can help identify substances, as different materials have characteristic densities. In this case, the density of the liquid is calculated to determine if it matches the known density of benzene.

Measurement and Calculation

Accurate measurement is crucial in chemistry, as it directly affects the results of calculations. In this scenario, the chemist measures the mass of the liquid and its volume to compute the density. The formula used is density = mass/volume, where mass is given in grams and volume in milliliters, leading to a calculated density that can be compared to the standard value.

Comparison with Standard Values

Comparing calculated values with standard or tabulated values is a common practice in chemistry to verify the identity of substances. In this case, the calculated density of the liquid is compared to the known density of benzene at a specific temperature. If the values are close, it suggests that the liquid is likely benzene; significant differences may indicate a different substance.