Chalcocite is an ore from which copper can be extracted for commercial use. The formula for this important ore is Cu2S. In the laboratory it is formed by the following reaction:
2Cu + S → Cu2S
The reaction takes place in laboratory conditions that allow the reactant atoms to move freely about in the reaction vessel. Explain this reaction in terms of collision theory.

Melting and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.

Match the following vocabulary terms to their definitions. 1. amount of energy required to change 1 gram of material from the solid to the liquid state at its melting point 2. a measure of the kinetic energy of the particles of a substance 3. the amount of heat energy required to raise the temperature of 1 gram of liquid water from 14.5°c to 15.5°c 4. amount of energy required to change 1 gram of material from the liquid to the gaseous state at its boiling point 5. the amount of energy required to change 1 gram of a substance 1°c a. temperature b. latent heat of vaporization c. latent heat of fusion d. calorie e. specific heat

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons