Explain how a secondary dominant chord functions to heighten tension and create a stronger resolution in a chord progression.

A secondary dominant chord is a dominant chord (V) that resolves to a chord other than the tonic (I). Its function is to temporarily tonicize a chord within a key, creating a stronger pull towards that chord and thereby heightening harmonic tension before the resolution. In the key of C major, the dominant chord is G7, which resolves to C. A secondary dominant, for example V/V, would be the dominant ....