Areaction of the form aa h products is second order with a rate constant of 0.169 l/(mol ∙ s). if the ini- tial concentration of a is 0.159 mol/l, how many seconds would it take for the concentration of a to decrease to 5.50 × 10−3 mol/l?

Point charges q1 = 51 µc and q2 = −27 µc are placed 1.0 m apart, with q2 on the right. what is the force (in n) on a third charge q3 = 19 µc placed midway between q1 and q2? (assume the positive direction is to the right. indicate the direction with the sign of your answer.)