Since potassium is more reactive, it will lose electrons to the less reactive, the copper. This is why potassium is on the positive side because it lost electrons; copper is on the negative side because it gained electrons. This will create a stronger reactions.
A battery stores electrical energy in the form of chemical energy. A battery has three parts to it: the anode, which is the negative end of a battery, the cathode, which is the positive end, and the electrolyte, which separates the two, but also allows . Electrons in the anode want to get to the cathode, so they are in need of a load, for example, a light bulb. All the chemical energy from the battery is used up when all the electrons from the cathode have transferred into in anode.
The pH scale measures how acidic or basic a substance is. Substances that measure less than 7 are acidic. On the other hand, substances that measure more than 7 are basic. Those that are exactly 7 are neutral; an example is water.
This is an example of a chemical reaction. It is a single replacement reaction, with the aluminum replacing the copper in the copper chloride solution. The copper than settles to the bottom, and the solution becomes an aluminum-chloride solution. The picture at the top shows many varying levels of copper chloride for the same reaction. The picture at the bottom shows the solution where the copper is balanced with the aluminum, so the solution is clear, with the copper at the bottom
The 0.75g beaker is mostly clear because the aluminum and copper are balanced, leaving only chloride, which is colorless, in the solution. The remaining aluminum and copper sit at the bottom of the beaker.
My post is in the description of the video on YouTube.
This is my own upload.
Because the 2g beaker has more copper chloride than the 0.75g beaker, its solution is more concentrated. This is a single replacement reaction because the copper and the aluminum switch places. In the 2g beaker, there is more copper than aluminum, which is why all the aluminum was dissolved so quickly.