Question

63. For each of the following situations, you are asked which of two objects or substances has the higher energy. Explain your answer with reference to the capacity of each to do work and say whether the energy that distinguishes them is kinetic energy or potential energy. a. (1) A methane molecule, CH4, in the stratosphere or (2) a CH3 molecule and a hydrogen atom formed from breaking one of the carbon-hydrogen bonds in a CH4 molecule. b. (1) A water molecule moving at 1.63 x 103 mi/h or (2) the same water molecule moving at 1.81 x 103 mi/h. (These are the average velocities of water molecules at 110 °C and 200 °C.) c. (1) Iodine solid or (2) iodine gas. (Assume that the two systems are at the same temperature.) d. (1) A nitrogen monoxide, NO, molecule and an oxygen atom in the stratosphere or (2) the NO2 molecule that can form when they collide. e. (1) Two bar magnets pushed together with the north pole of one magnet almost touching the south pole of the other magnet or (2) the same magnets farther apart. f. (1) A water molecule moving at 1.63 x 103 mi/h or (2) a uranium hexafluoride, UF6, molecule moving at the same velocity.

Answer 1

a) (2) The CH₃ molecule and a hydrogen atom formed from breaking of one of C-H bonds in a CH₄ molecule. This has higher potential energy

b) For the same mass, Kinetic energy depends on square of the velocity. Since, velocity of 2nd water molecule is higher, it will have higher kinetic energy.

3) Iodine gas has higher kinetic energy (lesser forces of attraction between molecules in gas)

4) NO₂ molecule that forms when it NO and oxygen atom collides has higher kinetic energy

5) Two magnets closer together with north pole of one magnet nearly touching south pole of another magnet (higher kinetic energy since they are pushed towards one another)

6) For the same velocity, Kinetic energy is proportional to mass of the material. Since UF₆ has a higher mass it has a higher kinetic energy