This is an Amazing resource for modeling science topics with simulations! Run by the University of Colorado at Boulder, there are tons of interactive simulations including ones I've used in my classes that are very helpful in visualizing certain topics. The website also has shared activities from teachers across the country including lesson plans, homework, demos, and labs for all grade levels!
This is a site from the University of Illinois that shows various chemistry demonstrations that are performed in the general chemistry lectures. It also shows how to set up these demonstrations.
I found this site when looking for ideas to use in an upcoming demo/lesson about chemical and physical properties/changes. I guess there are only 25 experiments listed currently, but it gave me some good ideas to potentially use!