How do you do these AP Chem questions?

Question

1. A 26.27 g sample of a solid is placed in a flask. Toluene, in which the solid is insoluble, is added to the flask so that the total volume of the solid together is 50.00mL. The solid and the toluene together have a mass of 52.65g. The density of toluene at the experimental temperature is 0.864 g/mL. What is the density of the solid?

2. Suppose you define your own temperature scale (G) using the freezing point (-115°C) and the boiling point (197.6°C) of ethylene glycol (The main ingredient in automotive antifreeze). You set the freezing point of ethylene glycol as 0°G and the boiling point as 100°G. On the G temperature scale, what is the temperature for the freezing point of water?

Answer 1

Since the density question has been answered I will answer the temperature question. Since this is out of the Chemistry: The central science text book the known answer is 5.5 deg. Also, ethylene glycol freezing point is not 115 degree is actually around 11.5.

197.6 + 11.5 = 209.1

Since the range to define the new temperature is 0 to 100 the range is 100 deg, so:

209.1 / 100 = 2.091

2.091 means that to 1 degree  of C is 2.091 degree of G on the new temperature scale.

Now since the freezing point of ethylene glycol has been change from -11.5 deg to 0 deg from this we know the range is 11.5 and we know that the freezing point of water is 0 deg as the equation followed:

(range - freezing point of water) / New temperature scale
(11.5 - 0) / 2.091 = 5.49976088 deg
                   = 5.50 deg G

Therefore the new freezing point of water is 5.50 deg G.