How do the pace and tone change in this chapter? How does Steinbeck achieve this new pace and tone?

This is pretty much the question you asked before. Steinbeck shifts the tone and mood to something other than the Joads and their plight. Here he looks at the economic system of exploitation in more general terms. The selling of cars people can't really afford, profit by misery. The sales are fast and high pressured and the tone is unfeeling and exploitive.