Hi PF! I have a lab report to do about a gas thermometer experience that I couldn't do. I'm very saddened about this because I should have manipulate mercury but the earlier group broke a container of mercury and so the class had to be disinfected and closed for some days. Basically it consists of calibrating a gas (air) thermometer in order to evaluate the room temperature. (This picture explains how is the device : http://www.shef.ac.uk/physics/teaching/phy001/fig1.gif [Broken] . For further explanations of what is a gas thermometer, read this : http://en.wikipedia.org/wiki/Gas_thermometer) So the professor gave us the results the first class obtained and told us to work on it to get the final result. Furthermore he asked a few questions to be answered in the lab report. One of these questions is : What if the liquid used is water instead of mercury? My thought is that water would go up more than mercury because it is quite less dense. So as the column of the thermometer is only 47 cm and that the mercury went up to 16.5 cm for a gas temperature of 98,488 °C, the thermometer of water wouldn't be of any use for high temperatures (it would go up more than 47 cm and spread on the floor). Am I right? For low temperatures (0°C to 8°C), the water has a density's minimum at 4°C. Does it affect the lecture of measures? Also, if the air is say at -20°C, will the water freeze? Or not if I take the measure fast? I know it has a somewhat a low heat capacity so I wonder if the air temperature has a big effect. Another doubt: the mercury seems to have to big heat capacity, so when I heat up the air to 100°C, the mercury expand quite a lot and the column of mercury should go higher than if it were at room temperature. Does it makes “false” results? Is there anything else I can add to answer the professor's question?