The effect of temperature on the density of a liquid depends on the specific properties of the liquid in question. In general, as the temperature of a liquid increases, its density tends to decrease.
When a liquid is heated, the average kinetic energy of its molecules increases, causing them to move more rapidly and with greater spacing between them. This increased molecular motion leads to a decrease in the density of the liquid. The molecules are effectively spreading out and occupying a larger volume, which results in a decrease in the mass per unit volume, or density.
However, it's important to note that not all liquids behave the same way when heated. Some liquids exhibit anomalous behavior, where their density increases with temperature over certain temperature ranges. This behavior is seen in a few specific liquids, such as water near its freezing point (between 0°C and 4°C). As water is cooled from higher temperatures to near its freezing point, the density actually increases due to the formation of hydrogen bonds between water molecules, resulting in a more ordered and closely packed structure.
In most cases, though, the general trend is that the density of a liquid decreases as its temperature increases. This behavior is observed in common liquids such as oil, alcohol, gasoline, and many others.