se Table B in your Student Guide to answer the questions about ion concentrations. A solution with a pH = 13 has approximately how many moles of OH– ions per liter? How many moles of H+ would this same solution have per liter? (Use the decimal form of your answer.) A different solution with an H+ concentration of 1.0 × 10–4 would have a pH = .

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm