5.1 Flashcards
In what type of system does equilibrium occur?
Equilibrium occurs in a closed system, meaning that matter cannot enter or leave the system
What is Solubility Equilibrium?
Solubility Equilibrium is reached when the rate of dissolving equals the rate of crystallization
What must be present at Solubility Equilibrium?
Both dissolved and undissolved solute must be present at the same time
Fill in the blank: At Solubility Equilibrium, the concentration of the dissolved solute is _______.
constant
True or False: The concentrations of reactants and products vary constantly in a dynamic equilibrium.
False
What occurs at equal rates in a chemical equilibrium?
The forward and reverse reactions occur at equal rates
What is a closed system in the context of equilibria?
A system where no matter enters or leaves, allowing for equilibrium to be established.
What type of equilibrium is established at the melting/freezing point?
Solid/liquid equilibrium
At 0°C, what is the relationship between the rate of melting and the rate of freezing?
The rate of melting equals the rate of freezing.
What is the characteristic of gas pressure at equilibrium in a closed system?
The pressure of gas remains constant.
What defines quantitative reactions in an open system?
A chemical reaction that proceeds to completion, preventing reverse reactions.
How does equilibrium differ in a closed system compared to an open system?
In a closed system, an equilibrium can be reached, whereas in an open system, molecules can leave, preventing equilibrium.
What is an example of a reversible reaction?
The reaction between nitrogen dioxide (NO2) and nitric oxide (NO) at equilibrium.
What does it mean for an equilibrium to have the same composition regardless of approach?
It means the equilibrium will have the same composition whether approached from reactants or pure products.
What are the two ways to describe the state of chemical equilibrium?
a) Percentage reaction
b) Equilibrium constant
How is the equilibrium constant (K) defined for the reaction aA + bB ⇌ cC + dD?
K = |C|^c |D|^d / |A|^a |B|^b
Fill in the blank: At chemical equilibrium, the yield of product is measured as a percentage of the _______.
[maximum possible yield of product]
True or False: Chemical equilibrium can only occur in closed systems.
False
What is the significance of ‘58 kJ/mol’ in the context of chemical reactions?
It represents the heat involved in the reaction, indicating energy changes.
What is the formula for calculating percent reaction?
Percent reaction = (actual product yield / theoretical product yield) × 100%
The theoretical product yield is obtained from mole ratio and stoichiometric calculations.
What are the initial concentrations of hydrogen and iodine in experiment 1?
- H2(g): 1.00 mmol/L
- I2(g): 0.50 mmol/L
These concentrations are recorded before any reaction occurs.
What does ‘No reaction (NR)’ indicate in terms of reaction favorability?
Reactants favored
This indicates that the reaction does not proceed significantly towards products.
What percentage reaction indicates that reactants are favored?
< 50%
This suggests that the equilibrium position lies closer to the reactants than products.
What percentage reaction indicates that products are favored?
> 50%
This suggests that the equilibrium position lies closer to the products than reactants.
What is the equilibrium concentration of H2(g) at 448 °C after the reaction?
0.100 mmol/L
This is the concentration of hydrogen at equilibrium.
What is the equilibrium concentration of HI(g) at 448 °C?
2.00 mmol/L
This concentration represents the product formed at equilibrium.
In the context of chemical reactions, what does ‘quantitative’ mean?
Reaction proceeds to completion
This implies that all reactants are converted into products.
What is the average product yield if the actual yield is 1.56 mmol/L and the theoretical yield is 2.00 mmol/L?
78.0%
This is calculated using the percent reaction formula.
What is the significance of stoichiometric calculations in reversible reactions?
Used to calculate the concentrations of reactants and products at equilibrium
Stoichiometric calculations help predict the amounts of substances involved in a reaction.
Fill in the blank: The actual product yield is calculated from the equilibrium concentrations and is compared to the _______.
theoretical product yield
This comparison is essential for determining the efficiency of the reaction.
True or False: A reaction with a percent yield of > 99% indicates a complete conversion of reactants to products.
True
This indicates that the reaction has gone nearly to completion.
