Science Buddies: "Ask an Expert"

I have tried this experiment over and over with my son using an empty film canister. We have made sure that the canister has a tight fitting lid and we have packed the lid full of baking soda but every time we snap the lid on and turn it over to set it on the ground, the liquid just leaks out of the canister. What are we doing wrong? We've tried different containers as well with the same result. It is very aggravating that this project is not working for us. Please help.

Hi 5caseys,

I’m sorry that you’re having problems with your project. From your description you seem to have ruled out any issue with the film canister. Perhaps the problem is with packing the baking soda in the canister lid or another part of the procedure. There are some additional instructions on preparing the canister at this link:

https://www.sciencebuddies.org/science- ... structions

Hopefully you’ll find something in these instructions that will make your rocket launch. If not, post again and we’ll go from there.

I hope this helps. Please post again if you have more questions.

A. Norman

5caseys,

I have done this experiment many times, as well as its sister experiment with Alka Seltzer and water for fuel. To work well, the film capsule must be airtight or pressure will not be able to build up enough to cause launch. Despite the picture in the project write up, the capsules with lids that snap on the outside don't do well in this department. It sounds like this may be your trouble. Even though you changed capsules, if they were all of the same type, you can continue to have problems. What you want to use are the 35mm fujifilm capsules that snap on the inside. These are airtight and tend to perform quite well. I wasn't able to attach a picture of one, but I did include a link to an image of the ones I'm talking about.

http://www.google.co.uk/search?site=&so ... hiJBe1M%3A

If you try that, or already have, and continue to have trouble, please post back and we'll try to troubleshoot further.