Which of the following changes when a catalyst is used

Enthalpy of reaction

activation energy

both enthalpy of reaction and activation energy change

neither enthalpy of reaction nor activation change

Which statement accurately describes the relationship between air pressure, air density, or altitude? as altitude increases, pressure increases. as altitude increases, air density increases. air pressure and density are lowest at sea level. denser air exerts more pressure than less dense air.

Frictional forces acting on an object are often converted into energy, which causes the temperature of the object to rise slightly.

3. how much energy in joules is required to evaporate .0005 kg of liquid ammonia to vapor at the same temperature? 4. how much energy ( in megajoules ) is given up by .75 kg of water at 0c when it freezes to form ice at 0c? 5. explain how heat works between and at critical temperatures?