A 0.2m3 tank containing helium at 15 bar and 22 oC will be used to supply 4.5 moles per minute of helium at atmospheric pressure using a controlled adiabatic throttling valve. (1) If the tank is well insulated, what will be the pressure in the tank and the temperature of the gas stream leaving the throttling valve at any later time t? (2) If the tank is isothermal, what will be the pressure in the tank and the pressure in the tank as a function of time? Assuming helium to be an ideal gas with a constant heat capacity of 22 J/(mol K), and that there is no heat transfer between the tank and the gas.

Suppose a pair of chemical compounds a and b can react in two different ways: a + b -> c reaction 1 gives product c. a + b -> d reaction 2 gives product d. the following facts are known about the two reactions: . reaction 1 is endothermic and reaction 2 is exothermic. if a reaction vessel is charged (filled) with a and b , then at first d is produced faster than c. use these facts to sketch a qualitative reaction energy diagram for both reactions. note: because these sketches are only qualitative, the energies don? t have to be exact. they only have to have the right relationship to each other. for example, if one energy is less than another, that fact should be clear in your sketch.