ETSU GEN CHEM 2: LAB FINAK

Sols

Similar to solutions in that they pass through filter paper and do not settle when still.

Gels

less fluid character, examples are jello and whipped cream

Tyndall effect

Scattering of a light beam as it passes through a colloid

Does a true solution scatter light ?

No. the molecules are too small to do so //ions are too small.

colloidal dispersion: lyophilic

solvent attracting

- starch

- gelatin

theses substances are stabilized by the surface of the the particles.

colloidal dispersion: lyophobic

solvent fearing

stable because of preferential absorption of ions on the colloid particle surface. The repulsion forces between the absorbed like charges causes the particles to repel one another.

what are the two general methods that exist for the preparation of colloidal suspension and some of the properties of this interesting class of materials?

1. Condensation methods in which colloidal sized particles are formed by the building up of aggregate of ions or molecules

2. Dispersion methods which involve the breakdown of larger aggregates until the proper size is obtained

Gelatin is used as a _____

protective colloid

change in temperature equation

delta T = iKm

molality equation

mol of solute/kg of solvent (liters) helps me because they are about the same

What are the two types of water hardness?

1. Temporary

2. Permanent

temporary hardness

If the water contains the HCO3- ion in combination with Ca2+, Mg2+, or Fe2+, the water is classified as having temporary hardness.

permanent hardness

When anions such as So4^2- or Cl- are present as the counter ions.

How do you soften temporary hardness?

Heat softens temporary hardness

How do you soften permanent hardness

removal of unwanted ions. heat does not remove hardness from permanent hardness. Ion exchange will do the trick

What color is HY^2- + MgEBT

RED

What color is MgY^2- +HEBT

BLUE

How do you ensure completion of ion exchange?

the titration is performed at pH = 10 using an NH4OH/NH4Cl

how to calculate water hardness:

mol CaCO3 = mol EDTA = (mol EDTA/mL)(mL EDTA)

How to obtain ppm of CaCO3

ppm CaCO3 = mol CaCO3 * (100mg)/volume water sample

at what ppm is water considered soft?

less than 60 ppm

at what ppm is water considered hard?

60-120 ppm

at what ppm is water considered to be VERY HARD

greater ppm than 120

What factors does the rate of reaction depend on?

- temperature

- concentration

- nature of reacting species

- catalysts

For a given reaction, the concentration dependence of the rate is expressed by a ___________

rate law

How is the rate law determined

has to be determined through experiments

What is the general rule for concentration in terms of rate law?

the rate of reaction increases with an increase in the concentration of a reactant.

equation for rate law

rate = k [A]^m[B]^n

What is k in the rate law equation

rate constant

True or False

the rate of a reaction increases with increasing temperature

True

Equilibrium is characterized by the expression:

Kc = -[C]^c[D]^d/[A]^a[B]^b

Le Chatelier's Principle

when a change is imposed on a system at equilibrium, the position of the equilibrium shifts in a direction that tends to reduce the effect of that change

Beer-Lambert Law

A=ebc

Group V ions are:

slats are generally soluble and are not precipitated in any of the previous groups.

Group 4 ions

Ca2+

Ba2+

Grup 5 ions

NH4+

Na+

K+

Type of flame when sodium is present

FIREY LONG AND STRONG

type of flame when barium or potassium is present

intermittent and slow low burning