 As part of your lab experiment, you're going to determine the density of substances like solids and liquids. And today, as part of my demonstration, I'm going to show you how to calculate the density of water. In order for us to determine the density of water, we have to determine its weight and its volume. So in order to do this, I'm going to actually weigh 50 milliliters of water by placing it into a beaker. So in order to do this, I first have to determine the weight of my beaker. So I make sure that I zero my balance. I place my beaker on, and I record the weight. And it's telling me that the weight is 173.9 grams. Then I'm going to pour 50 milliliters of water into my beaker. And then I'm going to determine that weight. So the mass of the beaker plus water is actually 223.33 grams. So I can therefore determine the mass of the water by subtracting the mass of the beaker plus water from the mass of the beaker itself. So I'll determine that. OK, so this is the data that we have got from our measurement of the weight of water. So remember, the mass I got of the beaker plus the water was 223.33 grams. The mass of the beaker, which I weighed, was 173.9 grams. So we can determine, therefore, the mass of the water by subtracting mass of beaker plus water from mass of beaker, which you see here. The mass of the water is, therefore, 49.43 grams. So we know our mass of water. We also added a specific volume of water, which was 50 mils. So we know our weight of the water. We know the volume of the water. So therefore, we can calculate the density. So this is the equation that you have seen already. Density is equal to mass in grams over volume in mils. So in our case, the density of water is equal to the mass of water, which is 49.43. That's what we obtained, over 50 mils. And when we use our calculator, we get 0.989 grams per mil. So that is the density of water that we calculated based on our experimental data.