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Problem Set 3 • 1. Standard Temperature and Pressure (STP) is defined as a temperature of 0.00oC and a pressure of 100kPa. If the molar mass M of nitrogen is 14.0 g/mol, find the density (kg/m3) of nitrogen at STP [5 pts]. Nitrous Oxide or laughing gas is composed of the molecule N2O. If the molar mass of oxygen is 16.0g/mol, what is the density of N2O at STP? [5 pts] • 2. A hypodermic syringe contains medicine with the density of water. The barrel has a cross sectional area A=2.50x10-5m2, and the needle has a cross sectional area a=1.00x10-8m2. In the absence of a force on the plunger the pressure everywhere is 1 atm. A force F magnitude 2.00N acts on the plunger, making medicine squirt horizontally from the needle. Determine the speed of the medicine as it leaves the tip? [10pts] • • 3. A long rod, insulated from the sides is in perfect contact with boiling water and an ice water mixture. The rod consists of 1.00m section of copper and a length L2 of steel. Both sections have a cross sectional area of 4.00cm2. The temperature of the copper/steel junction is 65.0oC after steady-state has been setup. (a) How much heat per second flows from boiling water to the ice-water mixture? [5pts](b) What is the length of L2? [5pts] • • 4. Two speeding lead bullets, each of mass 5.00 g, at temperature 20oC, collides head on at speeds 500 m/s each. Assume its a perfectly inelastic collision and no loss of energy to the atmosphere. What is the final temperature of the system? [10 pts] Substance Latent Heat Fusion kJ/kg Melting Point °C Latent Heat Vaporization kJ/kg Boiling Point °C Lead[9] 23.0 327.5 871 1750 • Heat capacity of lead = 128J/kgoC (assume same for molten lead) • 5. Two thermally insulated vessels are connected by a narrow tube fitted with a valve that is initially closed. One vessel of volume 16.8L, contains oxygen at a temperature of 300K and a pressure of 1.75 atm. The other vessel, of volume 22.4L, also contains oxygen but at a temperature of 450K and a pressure of 2.25 atm. When the valve is opened and the temperature and pressure become uniform, (a) What is the final temperature? [5 pts] (b) What is the final Pressure? [5 pts]