is a compound that is added in small amount (a few drops) in acid-base titrations. It changes color over a certain acidity
range, and indicates the end of the titration.

Indicator?

Explanation:

not sure though

chemical energy is stored in the chemical bonds of atoms and molecules. it can only be seen when it is released in a chemical reaction. when chemical energy is released, the substance from which the energy came is often changed into an entirely different substance.

this chemical reaction releases energy in the form of light and heat. chemical energy is the potential energy stored in the arrangement of atoms within molecules. breaking chemical bonds requires energy, while forming new chemical bonds releases energy.

the atp molecule can store energy in the form of a high energy phosphate bond joining the terminal phosphate group to the rest of the molecule. in this form,energy can be stored at one location, then moved from one part of the cell to another, where it can be released to drive other biochemical reactions.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.