Question

Select the correct answer from each drop-down menu. A beaker containing a mixture of N2(g) and H2(g) is cooled by placing it in a tray of cold water. In response to the cooling, the likely number of collisions between the molecules of N2(g) and H2(g) will ____. The rate of the reaction will ____.

Answer 1

Cooling a mixture of N2(g) and H2(g) decreases the number of molecular collisions and the reaction rate, as the reduced temperature lowers the kinetic energy and velocity of the molecules, leading to fewer opportunities for reactant contact.

Step-by-step explanation:

A beaker containing a mixture of N2(g) and H2(g) is cooled by placing it in a tray of cold water. In response to the cooling, the likely number of collisions between the molecules of N2(g) and H2(g) will decrease. The rate of the reaction will decrease.

Cooling a mixture of gases reduces the kinetic energy of the molecules, which in turn reduces their velocities. Since the root mean square speed is proportional to the average kinetic energy, slower-moving molecules result in fewer collisions. Fewer collisions mean a lower chance for reactant particles to come into contact with each other, thereby slowing the reaction rate. This is particularly relevant for the exothermic formation of ammonia from nitrogen and hydrogen, where the rate of the reaction is highly dependent on temperature.