1. A heliox deep-sea diving mixture contains 2.0 g of oxygen to every 98.0 g of helium. What is the partial pressure of oxygen when this mixture is delivered at a total pressure of 9.0 atm? Express your answer using two significant figures.
2. Lithium reacts with nitrogen gas according to the reaction:
6Li(s)+N2 (g)→2Li3 N(s)
What mass of lithium (in g) is required to react completely with 58.1 mL of N2 gas at STP?
3. A frost-free refrigerator uses 630 kWh of electrical energy per year.
A. Express this amount of energy in J B. Express this amount of energy in kJ C. Express this amount of energy in Cal (Express your answer using three significant figures)
4. The air in an inflated balloon (defined as the system) is warmed over a toaster and absorbs 130 J of heat. As it expands, it does 75 kJ of work. What is the change in internal energy for the system? Express your answer using two significant figures.