hi everyone I'm so excited to say that I'm with Amelia at sanctum with school and we're going to be bringing science hazel to the lab so I'll be sharing lots of practicals Amelia's going to introduce herself hi my name is Amelia I am a lab technician I work in this school sometimes of school in Cambridge I am also an ambassador which means I go in other school to introduce science to the kids and we have a lot of fun together I have also an Instagram page Amelie about science and follow me to see all my experiments and videos yeah absolutely thank you in this rates of reaction video Amelia and I going to investigate the effect of surface area on the rate of reaction so in terms of our independent variable what we're changing we're altering the surface area of our marble chips so we have calcium carbonate in chip form over here versus its powdered form notice that the starting mass of both is the same so we have to control that particular variable the starting mass of the calcium carbonate also we need to try to control the temperature we're going to actually measure the rate of reaction by looking at how quickly the carbon dioxide is produced because remember if you react calcium carbonate with hydrochloric acid you're going to produce calcium chloride plus water plus the carbon dioxide that we measure one final control variable we need to be aware of is keeping the concentration of acid the same we're going to be using 0.5 molar in both experiments ok so I'm going to measure 25 ml of 0.5 molar hydrochloric acid and shall we start with the powder yeah yes so I'm going to start stop for me like hummed outside it's already been given off we can see the fizzing taking place so 30 seconds has passed okay the volume is 45 so we've produced 45 centimeter secure carbon dioxide using the powdered calcium carbonate we're now going to repeat the experiment this time using calcium carbonate chips and obviously maintain the same volume and concentration of hydrochloric acid okay again they don't have five molarity hydrochloric acid 25 cubic centimetre stopcock started waiting for those 30 seconds okay yep 30 seconds okay beside the body is five Wow it's much slower really okay so as we would expect the smallest surface area of the large calcium carbonate or cement that the volume of solid oxide produced in 30 seconds there's much less than that with the powdered limestone we can obviously calculate rates of reaction in order to do that just to change in volume divided by the time so that would be 30 seconds so for this experiment it'd be 5 divided by 30 [Music]