How many Star Trek episodes did Spock take over the enterprise and sit in Kirk's chair?

Spock took over the command of the USS Enterprise and sat in Captain Kirk's chair in two notable instances. The first was in the original series episode "The Menagerie," where he assumes command to bring the ship to Talos IV. The second instance occurs in the film "Star Trek II: The Wrath of Khan," where he briefly takes command during a critical moment.