STAAR Ladder to Success

Rung 5

Polarity

– The oxygen atom is bigger than the hydrogen atoms, the electrons spend more time around the oxygen. This creates a slight charge on each end of the water molecule.

Hydrogen Bonding

• The force of attraction between the hydrogen atom of one water molecule to the oxygen atom of another water molecule

• Easily done because of water’s bent shape- allowing the hydrogen to bond.

How does the structure of water relate to its nickname, “ the universal

solvent”?

A. It has a positive end and a negative end, and can therefore dissolve many compounds.

B. It has a very low specific heat.C. It loses heat very quickly.D. It has no electric charge and is therefore

able to associate with a variety of molecules.

Curve

• On the line = saturated

• Below the line = Unsaturated

• Above the line = Supersaturated

Solubility Rules

Molarity

• Concentration of a solution.

solution of liters

solute of moles(M)Molarity

total combined volume

substance being dissolved

• Example #1: What is the molarity of the solution if .25 moles of Na2SO4 is dissolved in 1.5 L solution?

• Example #2: If you had a 2M solution of glucose (C6H12O6) how many liters of the solution would contain 3 moles glucose?

• Example #3: Calculate the molarity of .51L of solution that contains 110g of NaCl.

2211 VMVM

Dilution

• Preparation of a desired solution by adding water to a concentrate ( stock solution).

• Moles of solute remain the same.

• Example #1: What volume of .5M NaOH is needed to make a .075 M in 2L solution?

Electrolytes

StrongElectrolyte

Non-Electrolyte

- +

salt

- +

sugar

- +

acetic acid

WeakElectrolyte

SATURATED SOLUTIONno more solute dissolves

UNSATURATED SOLUTIONmore solute dissolves

SUPERSATURATED SOLUTIONbecomes unstable, crystals form

concentration

Rate of Solution

• Solids dissolve faster...

– more stirring

– small particle size(increased surface area)

– high temperature

Rate of Solution

• Gases dissolve faster...

– no shaking or stirring

– high pressure

– low temperature

A solution that contains less solute than it can hold at a given temperature is

A. disassociated.B. saturated.C. supersaturated.D. unsaturated