A balloon is cooled by removing 0.784 kJ of heat. It shrinks on cooling, and the atmosphere does 655 J of work on the balloon. Calculate the change in internal energy, ∆E, of the system.

The correct answer is -0.129 kJ

Explanation:

In the given case, the cooling of the balloon is done by withdrawing 0.784 J of heat, and the work done by the atmosphere on the balloon is 655 J. First, there is a need to transform kJ into J, 1 kJ = 1000 J. So, 0.784 kJ would be 784 J.  

The ΔE or the change in the internal energy can be calculated by using the formula, ΔE = q + w (1).  

In the given case, q refers to the heat moved out of the system, that is, the value of q would be less than 0 or will be a negative quantity. Therefore, the heat moved out of the system will be -784 J. On the other hand, as the work or w is done on the system, therefore, the value of w would be more than 0 or will be a positive quantity. Thus, the value of w will be +655 J.  

Now putting the values in the equation (1) we get,  

ΔE = -784 J + 655 J

ΔE = -129 J or -0.129 kJ

As the change in internal energy comes out to be a negative value, therefore, the process is considered exothermic.  

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be