Hydraulic jack with chemical reaction

[Inil]

Hi,my teacher give us an assignment to build a hydraulic jack but using any chemical reaction to push the piston and need to be able to hold weight of 500g.(p/s:using recycled item).I tried it with a tube coming out of water bottle and connected to a 2 syringe which is the base to put the weight.In the water bottle,I use vinegar and baking soda to produce CO2 and push the piston.Unfortunately,it was only strong enough to push one syringe without the weight.Any idea/suggestion to make it better?