R constant of liquid water?
Let's start with the universal gas constant in metric units: R = 8.31446 joules per (mole Kelvin) Now let's change it to apply to water vapor, whose molar mass is 18 gram/mole. R = 0.461914 joules per (gram Kelvin) for H2O Next, let's convert joules to Btu and grams to pound-mass. R = 0.461914 (J/g K) x (1 Btu/1055 J) x (453.6 g/1 lbm) = 0.19860 Btu / (lbm K) If you want Fahrenheit degrees, multiply by 5/9: = 0.11033 Btu / (lbm degF) You asked about R for "liquid" water. There is no different R for liquid water different from that for gaseous water. Most applications of "R" are restricted to conditions where the substance is gaseous. Water is nearly incompressible. If what you really need is an "equation of state" for liquid water (comparable to the ideal gas law), consult Equation 19 in the reference below.
Does Charles Law show that at the absolute zero temperature volume of a gas becomes zero?
Yes. For a hypothetical “ideal gas” the volume at absolute zero is also zero. This is because the molecules of which the ideal gas is composed have zero volume.At ordinary temperatures and pressures, the volume of molecules is negligible so Charles’s Law works fine. However, working at high pressures in particular there are modified versions which allow for the volume of the molecules.The hypothetical ideal gas does not (of course) condense to a liquid, which real gases do because of interactions which are not accounted for in Charles’s Law.
Could Alpha Centauri have two Earth-like planet twins?
Could…. YesRealistically…. Not likely. The presence of three suns will make a stable orbit, and tilt difficult to maintain.Any planet that spends its entire orbit within the “goldilocks zone” must also have a mass simular to the Earth so that atmospheric pressure will allow water to be a liquid over a wide range of temperatures. Furthermore the planet must have a large moon to keep its tilt constant.
Why does increasing the pressure of water raise the boiling point?
think about it this way... when water heats up the molecules move faster and faster and move farther apart - eventually becoming steam. when you increase the pressure on the water you are in a way holding the molecules together more tightly. This helps keep them from moving apart so it requires more heat to get them to "break free" and move apart. So, the higher the water pressure the higher the boiling point. edit - if you pressurize water, heat it then rapidly then depressurize it the Temperature would not change, but it would become volatile and turn to "superheated steam" since under pressure water can remain a liquid beyond it's boiling point. when you depressurize it it will become steam right away. If you need an illustration find a you tube video of a moron taking the radiator cap off of a hot car, you will see what I am talking about!
How long would it take for 1 cup of water to evaporate under room temperature?
Evaporation rate depends on water temperature, air temperature, relative humidity, wind speed, how pure the water is (pure water evaporates at a faster rate than seawater) and so on. If there is dust in the water, different parts of the water can heat up more than others by absorption of solar radiation and therefore heating, etc. You could try the equation at Evaporation from Water Surfaces