Short Notice

Question 1.   The concepts of chemical bonds and valence provide a means of determining which molecules might form and, of these possibilities, which are likely to be stable and which are likely to be unstable. For instance, from the smoke in this picture we take two small molecules that contain only a single chemical bond to form hydrogen chloride (H–Cl). Describe the concept of chemical bonds and valence.  (200 word response)

Question 2.  Pressure is a measure of force expressed in force per unit of area. The basic SI unit of pressure is expressed in kilograms per square meter or Pascal. Explain how the pressure of compressed air in a SCBA storage cylinder is commonly monitored? Is there a difference between gauge pressure and absolute pressure? Why, or why not? What does it mean when the gauge on the SCBA is at 0?   (200 word response)