A liquid expands on heating. Explain briefly how its density will change with rise in temperature
When a liquid is heated, it absorbs energy and its individual molecules start to vibrate more rapidly. This increased molecular motion causes the liquid to expand in volume, leading to a decrease in density.
To understand how the density of a liquid changes with temperature, we need to consider two factors: the mass of the liquid and its volume.
1. Mass: When a liquid is heated, its mass remains constant. Heating does not typically change the number of molecules or atoms present in the liquid.
2. Volume: As mentioned earlier, when a liquid is heated, it expands. The increase in volume is due to the increased kinetic energy of the liquid molecules, which pushes them apart. This expansion leads to a decrease in density because density is defined as the mass divided by the volume.
Mathematically, density (ρ) is calculated using the formula:
Density = Mass (m) / Volume (V)
Since the mass remains constant, as the volume increases with an increase in temperature, the overall density of the liquid decreases. This means that as a liquid becomes warmer, its density decreases, and as it cools down, its density increases.
It is important to note that this behavior is not true for all liquids. Some liquids, such as water, follow this general trend, but there are exceptions. For example, water reaches its maximum density at around 4 degrees Celsius and expands when further cooled or heated. This is why ice floats on water.
To experimentally determine the density of a liquid at different temperatures, you can measure its mass and volume at each temperature and then calculate the density using the formula mentioned above.