Why do tables of densities always include the temperature for which the listed values hold?
because temperature causes things to expand or contract, changing its volume, so density changes.
Tables of densities always include the temperature for which the listed values hold because density is affected by changes in temperature. When an object is heated, it expands and its volume increases, while its mass remains the same. As a result, the density of the object decreases. Conversely, when an object is cooled, it contracts and its volume decreases, causing its density to increase.
To understand this concept, you can perform an experiment. Take a balloon filled with air and measure its volume and mass at room temperature. Then, place the balloon in a freezer and measure the volume and mass again once it has cooled down. You will notice that the volume of the balloon decreases while the mass remains the same, resulting in an increased density.
Since density depends on both the mass and volume of an object, it is crucial to account for the temperature at which the density measurements were taken. Different substances and materials have different temperature-dependent expansion or contraction rates, and this is why tables of densities provide specific temperature values for accurate comparisons and calculations.
In summary, tables of densities include the temperature for which the listed values hold because temperature affects the volume and mass of an object, leading to changes in its density.