 Hello and welcome to this video about volumetric glassware. Volumetric glassware is used to make a solution of a compound in known concentration with very high precision. To make sure that you are able to do this, you have to first of make sure that you have your pure compound in a known quantity. So if you have a solid, you can weigh off known quantity in a weighing boat and make sure that you know down how much this is, or you can have a liquid when you piped exact amount of liquid or you have a solution of known concentration and then you will dilute it into the new volumetric flask. To make sure that the concentration is as exact as possible, you have to make sure that everything that you weigh off is transferred into the volumetric flask. To do this, we are now going to carefully put this copper sulfate into the volumetric flask. So we have our volumetric flask, I am adding a funnel on top and then you pour in the copper sulfate. As you can see, there is always a bit of copper sulfate left in the weighing boat and in this case we are going to dissolve in water so we can rinse the weighing boat with water. This will also work with ethanol but for example if you would be using acetone then the weighing boat might dissolve in the acetone. And then fill up the volumetric flask up to or below the neck. When there is sufficient liquid in the volumetric flask, remove the funnel and gently shake to dissolve all of your compounds into your solvent. For some compounds this might not work and you might have to dissolve it in a beaker or in a round bottom flask by gently heating it and then letting it cool down before transferring it to the volumetric flask. After everything has dissolved, we can start filling up our flask towards the outline to get the perfect concentration. However, there is still some liquid left on the top part of our volumetric flask which we need to get rid of. To do that we can use a glass rod with a piece of tissue paper or you can use a spatula and then you carefully dip it into the volumetric flask and soak up all the liquid that's on the top part of the volumetric flask. Make sure you do not touch the liquid on the bottom part of the volumetric flask as that will actually remove some of the carefully weighed out solid or liquid that you had to start off with. When it's sufficiently dry, you can use a small pipette and a beaker of your solvent or you can use a tiny flask and make sure that when you add in your liquid now that it does not touch the top part of the volumetric flask. As you can see, I accidentally actually got some droplets here so I have to make sure it's dry before I continue. Now to carefully do the last part. What we want to end up with is the meniscus touching the line on your volumetric flask. This might be yellow and in some cases it's a blue line. That doesn't matter as long as it's at the correct position. A tiny bit more and there we go. Perfectly with the bottom of the meniscus on the yellow line. Now the only thing that remains is stop ring and vigorously shaking to make sure that it's properly dispersed throughout the whole solution and not spilling anything. That also works. Holding it upside down. Now that it's been mixed properly, you can see that the neck is a bit wet but that doesn't matter anymore because we already set the volume before mixing so we know that the total liquid in this flask is now the correct concentration that we wanted to have or of the known concentration that we can now calculate. And that's how you use volumetric flask.