28. (4 points)What is the percentage of water in the hydrate copper sulfate pentahydride – ( CuSO₄ * 5H₂O)? Answer all parts of this question – Show your work a) (1 points) Total mass of compound b) (1 points)Mass of water in compound c) (2 Points)Percentage of water in compound.
percent of water = mass of water / mass of hydrate x 100%

29. (3 points) A gas has a volume of 725 mL at a temperature of –35.0°C. What volume will the gas occupy at 25.0°C? Show your work.( points awarded 1 point for correct answer, 1 point for work, 1 point for correct set up ) *
Use Charles' Law. Make sure temperature is in Kelvin

30. (2 points) Why are there different directions for cooking things at high altitude than cooking things at sea level? *

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1) Total mass of the compound: 
  = CuSO₄ * 5H₂O
 = 63.5 + 32 + 16*4 + 5[1 * 2 + 16]
 = 95.5 + 64 + 90
 = 249.5 amu

b) Mass of water in compound = 5H2O = 5 [1 * 2 + 16] = 90 amu

c) Percentage of water = 90/249.5 * 100 = 36.07%

29) We know, Equation of Charles law:
 V1T1 = V2T2
Here, V1 = 725 mL
T1 = -35 + 273 = 238 K
T2 = 25 + 273 = 298 K

Substitute their values, 
725*238 = v2*298
v2 = 172550 / 298
v2 = 579.02 mL

30.) At higher altitudes, Atmospheric pressure is very lower, 
so foods take longer to cook. In order to save some time due to such a low pressure, there are some instructions for that.

Hope this helps!