8. Thermochemistry

A radioactive particle weighing 7.20 x 10³ ng is found 110 m above the earth's surface. What is its potential energy?

What must be added to water in order to change state from liquid to a gas?

What happens to the molecules that make up a chocolate chip as it is heated in the oven?

The energy stored in the chemical bonds of fossil fuels is a form of __________ energy.

Which would most likely cause an increase in the energy of water molecules in liquid water?

The mass of a helium atom is roughly four times that of a hydrogen atom. The mass of an oxygen atom is roughly 16 times that of a hydrogen atom.

a. For each of the following pairs, choose the one that has the greater kinetic energy: (i) a H atom moving at 1000 m/s or a He atom moving at 400 m/s, (ii) a H atom moving at 1000 m/s or an O atom moving at 400 m/s, (iii) a He atom moving at 1000 m/s or an O atom moving at 400 m/s.

b. A He atom is moving at 800 m/s. What is the speed of an O atom that has the same kinetic energy as the He atom?

The blue curve in the plot here shows the potential energy of an ion A interacting with an ion B as a function of their separation distance. The red curve shows the interaction of ion A with a different ion (ion C) as a function of separation.

a. Do the charges on ions A and B have the same or different signs?

b. Do the charges on ions A and C have the same or different signs?

c. Is the magnitude of the charge on ion B greater than, equal to, or less than the magnitude of the charge on ion C?