Answer check:

Define a catalyst and explain a catalyst's role in a chemical reaction.

A catalyst is a substance that speeds a chemical reaction without being permanently changed itself. It works by providing a convenient surface for the reaction to occur. The reacting particles gather on the catalyst surface and collide more frequently with each other and more of the collisions result in a reaction between particles because the catalyst can lower the activation energy for the reaction.

That looks good to me.

expected outcome of the lab experiment density alcohol and water???

To verify this answer, you would need to ensure that it accurately defines a catalyst and explains its role in a chemical reaction. You can do this by checking if the following points are covered:

1. Definition of a catalyst: It should state that a catalyst is a substance that speeds up a chemical reaction without being permanently changed itself.

2. Role of a catalyst: It should explain that a catalyst provides a convenient surface for the reaction to occur. It should mention that the reacting particles gather on the catalyst surface and collide more frequently with each other. Additionally, it should specify that the catalyst lowers the activation energy for the reaction, allowing more collisions to result in a chemical reaction.

If all of these points are covered accurately, then the answer is correct.