3. A sample of neon gas has a volume of 1.2 L at 28.5°C. What will the volume be at 125°C it the pressure remains constant?

1.58L

Explanation:

Given parameters:

Initial volume  = 1.2L

Initial temperature  = 28.5°C  = 28.5 + 273  = 301.5K

Final temperature  = 125°C  = 125 + 273  = 398K

Unknown:

New volume  = ?

Solution:

Volume and temperature relationship is resolved using the Charles's law.

The law states that "the volume of a fixed mass of a gas varies directly as its absolute temperature if the the pressure is constant".

So;

           =  

V1 is the initial volume

T1 is the initial temperature

V2 is the new volume

T2 is the new temperature

                 =    

              301.5V2  = 477.6

                       V2  = 1.58L

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%