Chem lab 123 final exam

Beer-Lambert Law

A=measured absorbance
€=molar absorpitivity
b=path length
c=concentration

What is the unit for absorbance

No unit

What is the unit for €

Molar absorptivity L/(mol•cm)

What is the unit for b

Path length cm

What is the unit for c

Concentration mol/L

Why is a spectrophotometer must be blanked

Has only one detector so it is nescessary to measure the intensity of light originating from the source prior to placing sample in sample cell

A student transfers a sample to a cuber and places it into the spectrophotometer. She scans the anaylte from 400nm to 720nm. What is the name of the plot? What is the y axis? What is the x axis?

Absorbance spectrum
Absorbance
Wavelength(nm)

What is lambda max?

The wavelength at which a sample has the greatest aborbance of light.

Transmittance

The passing of light through a sample

Coordination complex

formed through the reaction of a transition metal cation with a ligand

complex ion

charged species consisting of metal ion surrounded by ligands

ligand

The reactant that binds to the metal cation

What is the ideal gas law?

PV=nRT

Pressure vs. temperature

direct relationship

Pressure vs. mass

Direct relationship

Pressure vs. volume

Indirect relationship

How do you hold volume constant in pressure vs. temperature

Securing the 10mL syringe with a rubber band

How do you hold volume and temperature constant in pressure vs. mass

Experiment taken place in 2L bottle with no change it atm temp

How do you hold temperature and number of moles in pressure vs. volume

Nothing was being added or taken away nor did temp change

Hess's Law

the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process

Reactants in enthalpy reaction lab

Reaction 1: NaOH
Reaction 2: NaOH(aq) and H
Reaction 3: NaOH(s) and H

exothermic reaction

a chemical reaction in which heat is released to the surroundings

endothermic reaction

A reaction in which energy is absorbed

rate constant k

Varies with temperature and the reaction environment

zero order reaction

rate is independent of the concentration of the reactant.

first order reaction

a reaction in which the reaction rate is proportional to the concentration of only one reactant

second order reaction

a reaction whose rate depends on the concentration of one reactant raised to the second power or on the concentrations of two different reactants, each raised to the first power

overall reaction order

the sum of all the exponents in a rate law expression

Clock Reaction

a reaction in which some visible change takes place in the reaction mixture when a certain point in the reaction is reached

rate of reaction

measure of how fast a chemical reaction occurs

Starch reacts with what to turn blue

Triiodide

Did the change in color of the solution reflect the concentration change?

The color changed to a lighter orange resulting in a change of concentration. The number reflects this because it got smaller

If the reaction was allowed to proceed to completion in activation energy lab, what color would it be

Clear

bidentate or chelating ligand

When a ligand forms two bonds to a metal ion in a coordination complex

Arrehenius equation

k = Ae^(-Ea/RT)

k=Ae^(-Ea/RT)

Eaactivation energy of the reaction
T-temp K
A-frequency factor constant
R-gas constant 8.314 J/K•mol

If the equilibrium constant is a very small value the equilbrium system will lie towards the...

Left
Nostly starting reagents and very little product

If the equilibrium constant is a very large value the equilibrium system will lie towards the..

Right
Mostly products very little reactants