What is "v'Chatas Amecha"?
Rashi: If Chatas was connected to Amecha (sin of your nation), the last vowel of Chatas would be Patach. Rather, it brings sin to your nation.
Hadar Zekenim (verse 9): Chatas is lack. The lack of bricks is to your nation, for you do not give to us straw.
Ibn Ezra, Rosh: Your nation will sin. V'Chatas is a verb; "Am" is sometimes feminine. 1
Ibn Ezra: Really, Pharaoh sins, but Derech ha'Musar they attributed it to his nation.