I have made a simulation of the marble chips and acid experiment at four different concentrations of acid. Just double click on the “gas syringe.html” file and it will open in your web browser. You could use browser zoom controls to make it huge if you wish. Maybe take measurements of volume of gas evolved against time or just use to introduce the experiment or revise. ( the price for this could save your department many times in broken gas syringes.)
Please note: in order to provide a rich interactive experience, my resources are mini-web sites local to your computer. After unzipping, they comprise a folder containing the main .html file and another folder containing the graphic resources and my coding to make the resource work. Double click on the .html file and the resource will work. If, however , you move or delete any of the files from this hierarchy, the resource will not work.