Question

The freezing point lowering of a saturated aqueous solution of NaCl is 17 Celsius. Would spreading salt on the icy sidewalks be beneficial when the temperature outside is -8 Fahrenheit? Explain.

Answer 1

What's your main problem with this? Is it not obvious that if NaCl will lower the f.p. by 17 C and the T is -8 then ....... What is the f.p. of pure H2O?

Answer 2

I'm not sure as to whether or not spreading salt on sidewalks would be beneficial, considering the outside temperature. The freezing point of pure H2O is 0 °C or 32 °F. But Im not sure what that would infer?

Answer 3

The freezing point is zero C normally. Spreading (or spraying) saturated NaCl solution CAN lower it by 17 degrees C according to the problem. The temperature is only -8 C, therefore, the ice would melt. In fact it would melt with an outside temperature of -16 C but it would not melt the ice if the outside temperature were -17 or lower. Anything higher than -17, yes.