Which weighs more: a liter of water at 20 degrees C or a liter of water at 80 degrees C. Explain.

Look up the density of water at 20 C and the density at 80 C and use mass = volume x density to calculate the mass of 1000 mL at those two temperatures. You can type "table density H2O versus temperature" into Google and find a table. If you have trouble locating it I can help you find it.

Well, let me put it this way: both of them weigh a liter! But if you're asking about the density, then the water at 20 degrees C would be slightly denser than the water at 80 degrees C. So, you may say the 20 degrees water is the "heavyweight champion" in terms of density, but don't worry, they both still weigh a liter, and I promise they won't be causing any problems on your bathroom scale!

A liter of water at 80 degrees C weighs slightly less than a liter of water at 20 degrees C. This is because the density of water decreases as its temperature increases.

The density of a substance refers to how much mass it has in a specific volume. When water is heated, its molecules gain energy and move faster, causing them to spread out slightly and increase the volume occupied by the same amount of mass. Since a liter is a measure of volume, a liter of water at a higher temperature will have a larger volume compared to the same amount of water at a lower temperature.

However, the mass of the water remains the same regardless of its temperature. Therefore, a liter of water at 80 degrees C will have less mass compared to a liter of water at 20 degrees C.

To determine which weighs more, a liter of water at 20 degrees Celsius or a liter of water at 80 degrees Celsius, we need to understand the concept of density.

Density is the measure of mass per unit volume of a substance. When the temperature of a substance changes, its density also changes. In the case of water, its density decreases as its temperature increases.

Typically, water at 20 degrees Celsius has a density of around 998 kilograms per cubic meter (kg/m³), while water at 80 degrees Celsius has a density of approximately 971 kg/m³. This means that a liter of water at 20 degrees Celsius would weigh about 998 grams, whereas a liter of water at 80 degrees Celsius would weigh approximately 971 grams.

Therefore, a liter of water at 20 degrees Celsius weighs more than a liter of water at 80 degrees Celsius. This is because the decrease in density as the temperature increases results in less mass per unit volume.