How to Balance Redox Equations? Cu + HNO3 -> Cu(NO3)2 +N2O + H2O

I can usually follow along when my professor does these, but I'm confused how to start them on my own when they have compounds instead of just elements.

Assuming complete dissociation of the solute, how many grams of kno3 must be added to 275 ml of water to produce a solution that freezes at -14.5 c? the freezing point for pure water is 0.0 c and k_f is equal to 1.86 c/m