making ice cream involves surrounding the ice cream canister with a bath of salt ice water. to get the mix of freeze at 7.00 C,how many grams of salt (NaCl;molar mass = 58) will you need to add to 3.5 kg of ice water bath? (Kf of water = 1.86C/m)

delta T = i*Kf*molality
You know delta T, i=2 (2 particles for NaCl), you know Kf, solve for molality.
Then molality = moles/kg solvent
Solve for moles.
Then moles = grams/molar mass.'
Solve for grams Nacl.