For my friend (RAY)

#1 Distinguish between a "wet" gas and a "dry" gas.

Dry gas is almost completely composed of methane. It is what remains after all liquefied hydrocarbons and non-hydrocarbons impurities are removed from the system. They are used in heating and cooling systems for electrical power generation.

Wet gas on the other hand contains less than 85 % of methane and large percentages of it are liquid natural gases such as ethane and butane. They are used in refrigeration and freezing systems.

Source:

http://www.usenergydevcorp.com

Retrieved: http://www.usenergydevcorp.com/media_downloads/Natural%20Gas%20Dry%20Vs%20Wet_050913.pdf

#2 A bicycle tire contains nitrogen, oxygen and argon gases. If the partial pressures are 51.0 psi, 13.5 psi, and 0.5 psi, what is the total pressure (in atm)?

Dalton's law (also called Dalton's law of partial pressures) states that the total pressure exerted by the mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases.

so

Ptotal = Pnitrogen + Poxygen + Pargon

Ptotal = 51 + 13.5 + 0.5 psi

Ptotal = 65 psi

Converting it to atm:

1 atm = 14.7 psi

Ptotal = 65 psi (1 atm / 14.7 psi)

Ptotal = 4.42 atm (Final answer)

#3 The solubility of sugar is 110g/100g water at 30 degrees, Celcius. If a solution contains 95g of sugar in 25g of water at 30 degrees Celcius, is the solution saturated, unsaturated, or supersaturated?

Definitions:

Saturated solution:

 A solution that can hold no more of the solute at a particular temperature is said to be a saturated    solution at that temperature.

Unsaturated solution:

 An unsaturated solution is a solution, which contains less amount of solute than is required to saturate it    at that temperature.

Super Saturated solution

Solution that is more concentrated than a saturated solution is known as super saturated solution.

Source:

http://www.citycollegiate.com/chapter3g.htm

First we need to know how much sugar is only soluble with 25 g of water:

Sugar soluble = 25 g water (110 g sugar / 100 g water )

Sugar soluble = 27.5 g

Thus only 27.5 g of sugar is soluble, there is an excess of 95-27.5 = 67.5 g of sugar in the solution. Thus it is a supersaturated solution.

#4 What is the molar concentration of a saturated solution of calcium hydroxide that contains 0.185 g of solute in 100.0 ml of solution?

Molarity can be used to express molar concentration of a solution. By definition

Molarity (M) = moles solute / liters solution

Molar mass of calcium hydroxide (Ca (OH)2):

Ca = 40.078 g/mol

O = 16 g/mol

H = 1.008

So molar mass of Ca (OH)2 = 40.078 + 2(16 + 1.008 ) g/mol

Molar mass of Ca (OH)2 = 74.094

Molar mass = 74.094 g/mol

Now we find the number of moles in 0.185 g of (Ca (OH) 2:

Let x = number of moles

x = 0.185 g / 74.094 g/mol

x = 2.5x10-3 moles

Also we need to convert volume in terms of liters:

Volume = 100 ml ( 1 L/1000 m l) = 0.1 L

Going back to formula of concentration:

Molarity (M) = moles solute / liters solution

Molarity (M) = 2.5x10-3 moles / 0.1 L

Molarity (M) = 0.025 M (Final Answer)