The vapor pressure of the liquid hf is measured at different temperatures. the following vapor pressure data are obtained: temperature 270.6k and 287.5k, pressure 324.5 mmhg and 626.9 mmhg. calculate the enthapy of vaporization ( delta h vap ) in kj/mol for this liquid.

Students design a model roller-coaster track. they place a rubber ball at the highest point on the track and let it go. the ball rolls along the track pulled only by the force of gravity. eventually, it comes to a stop. which change to the design will result in the ball moving the greatest distance?

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?

Match each type of lever with the correct diagram. 1. first-class 2. third-class 3. second-class