In this video, I'll talk about how the density of a liquid changes with the temperature. And as an example, I have chosen the liquid to be mercury. The density of mercury is 13.534 gram per cubic centimeter or in other words that means if you take one cubic centimeter of mercury the mass of the mercury will be 13.53 and this one is at 20 degrees celsius now if the temperature changes so how does the density change and we have to find out the density of mercury at 250 degree celsius. So what happens here is if the temperature changes in general the volume increases and you know that the density is mass per unit volume so if with the increase in temperature if the volume increases that means the density has to decrease. Let's figure out by exactly what is the density at 250 degree Celsius.
So these are the given values. the density of mercury at 20 degrees Celsius that I call this one is a rho I which is the notation for the density and I stands for the initial and the ti the initial temperature or the given temperature is 20 degrees celsius and the final temperature at which we have to find out the density of mercury is 250 degrees celsius and the beta here this is the the volume expansion coefficient of mercury and if you are if you do not know the values you can google the uh volume expansion coefficient of different materials. So the density of mercury with the temperature is given by this formula here. And if you want to know how did you get this formula, please watch my other videos that I will provide the link in the description section below.
So here I'm just using this formula here. And what does this formula tell you? So you see, if the beta is positive, if the beta...
is positive that means the density will decrease with each increase in temperature and for most of the materials and in most cases the volume increases with increase in temperature but there are certain materials whose volume decreases in fact with increase in temperature. One of the example is the water tube. If you look the the water between 0 to 4 degrees Celsius the volume in effect decreases or in other words the water is most dense at four degrees celsius and that's the reason the all the fishes the animals in the water survives even during the extreme cold temperature because there's still the liquid water at the bottom of a lake or a bottom of frozen lake so nevertheless let's come back here so this is the density uh for with the change in the temperature.
So the initial density is 13.534 which is given at 20 degrees Celsius. The one is a constant the beta value which is the volume expansion coefficient is given by this formula and change in temperature if you look at the change in temperature we're going from 20 degrees Celsius to 250 degrees Celsius so the change in temperature is now 230. So if I plug in all the the values what i get is 12.99 which is 13 gram per cubic centimeter okay so this is the density now so it has changed quite a bit okay from 13.53 to 13 gram with the change in temperature of 230 degrees celsius so this is it from this chapter if you have any questions write down your questions in the comment section below and do not forget to to like, share and subscribe the channel. Thank you very much.