An insulated 8m* rigid tank contains air, modeled as an ideal gas, at 600kpa and 400k. a valve connected to the tank is opened and air is allowed to escape until the pressure drops to 200kpa. the air temperature is held constant during the process by an electric heater placed in the tank. determine the electrical energy supplied to the air during this process. internal energy of the initial air is u = 286.1 6hĺ kg ; the enthalpy of the exiting air is hvit400.98hj/ kg

Explanation:

We assumes that all the electrical energy produced will be converted into the heat energy.

    Electrical energy input = Heat energy absorbed by object = Heat energy required = Q

As,        Q = U - W

                = U - RT

Since, it is given that U = 286.1 kJ/kg, is 600 kPa, is 200 kPa, and T is 400 K.

Therefore, putting these given values into the above formula is as follows.

          Q = U - RT

              =

              =

              = 412.27 kJ/kg

Thus, we can conclude that the electrical energy supplied to air is 412.27 kJ/kg.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation:

two years ago, when picking flowers in the mountains back of yosemite valley, i found a book. it was blotted and storm-beaten; all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however; many of the inner pages were well preserved. and although all were more or less stained and torn, whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today; its granite pages have been torn and blurred by the same storms that wasted the castaway book.

two years ago, when picking flowers in the mountains back of yosemite valley; i found a book. it was blotted and storm-beaten, all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however, many of the inner pages were well preserved. and although all were more or less stained and torn; whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today, its granite pages have been torn and blurred by the same storms that wasted the castaway book.