Answer:
In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed.
The balanced chemical reaction is:
N2 + 3H2 = 2NH3
We are given the amount of hydrogen gas to be used in the reaction. This will be the starting point of the calculations.
24.0 mol H2 (2 mol NH3 / 3 mol H2 ) = 16 mol NH3
Therefore, ammonia produced from the reaction given is 16 moles.
The water gets cold because the ice cube is endothermic. Which means it takes in heat. It takes the warmth from the water and melts the ice cube which the ice cube releases coldness which cools down the water.