Equilibrium Flashcards
(9 cards)
The main objectives for Experiment EQB and its in/post-lab assignment are (select all that apply):
Determine the relationship between the concentration of [Fe(NCS)]2+ and the absorbance to find this analyte’s molar absorption coefficient
Convert the absorbance measurements from equilibrium samples to concentrations of the product at equilibrium
Determine the equilibrium constant for the reaction of NaSCN and Fe(NO3)3 to form [Fe(NCS)]2+
What physical property of which compound are you monitoring?
The UV/Visible absorption of the product, [Fe(NCS)]2+
Le Chatelier’s Principle states that:
a chemical reaction will always restore equilibrium when perturbed
The equilibrium below is the reaction of interest.
Fe3+ +SCN- <–> [Fe(NCS)]2+
a. In the preparation of the standard solutions, which reactant will be used in excess?
b. Which reactant will essentially be converted entirely to product?
a. Fe(NO3)3
b. NaSCN
Temperature is NOT a factor we will be considering this class period. However, the reaction in question is an exothermic reaction. Select all of the following conditions that could perturb the reaction to proceed in the forward direction.
adding more reactant
removing heat
A volumetric flask has the following characteristics (select all that apply):
Glassware that can give volumes 3 to 4 significant figures
Can have a glass joint stopper
Has a flat base
Has a tare mark in the neck for the exact volume
Can have a plastic joint stopper
Select all equipment items below that you will use in some capacity during the EQB lab
Plastic transfer pipettes
Micropipette tips
Cuvettes
Micropipettes
10-mL volumetric flask with a yellow plastic cap
Scintillation vials
Beaker
What do chemical equilibrium constants tell us about the reaction?
The extent to which a reaction occurs
True or false: 1.00 molar nitric acid, not deionized water, will be used when preparing the Fe(NO3)3 stock solution, preparing the blank cuvette sample, and diluting all standard/equilibrium cuvette samples.
True
