Which of the following equations best describes the energy at point C, assuming energy is conserved?
O A. PEA= KEC
o B. PEA= KEc + PEC
C. PEg= KEC + PEC
O D. PEg = PEC

The correct option is

B. PEA = KEC + PEC

Explanation:

The potential energy is the energy possessed due to position

From the image the point with the highest position and therefore the most potential energy and the lowest or zero kinetic energy is point A

Given that we have;

Total mechanical energy = The potential energy +  The kinetic energy

Where there is constant total mechanical energy in the system, then, at the point A where the kinetic energy is zero, the potential energy is equal to the total mechanical of the system, we have;

Total mechanical energy = The potential energy at A = PEA

Total mechanical energy = PEA

At point C where we have the total mechanical energy presented as follows;

Total mechanical energy = Kinetic energy at C + Potential energy at C

Total mechanical energy = KEC + PEC

Therefore;

PEA = KEC + PEC.

n2(g) + 3h2-> 2nh3(g)   this is the balanced equation

note the mole ratio between n2, h2 and nh3.   it is 1 : 3 : 2   this will be important.

moles n2 present = 28.0 g n2 x 1 mole n2/28 g = 1 mole n2 present

moles h2 present = 25.0 g h2 x 1 mole h2/2 g = 12.5 moles h2 present

based on mole ratio, n2 is limiting in this situation because there is more than enough h2 but not enough n2.

moles nh3 that can be produced = 1 mole n2 x 2 moles nh3/mole n2 = 2 moles nh3 can be produced

grams of nh3 that can be produced = 2 moles nh3 x 17 g/mole = 34 grams of nh3 can be produced

note:   the key to this problem is recognizing that n2 is limiting, and therefore limits how much nh3 can be produced.