Simple Equilibria and Acid-base reactions Flashcards
What is the LeChateliers principle?
When a system in dynamic equilibrium is subject to a change, the position of the equilibrium will shift to minimise the change.
What is dynamic equilibrium?
The equilibrium when the rate of forward reaction is equal to the rate of the reverse reaction, therefore concentrations are constant.
How can you alter the position of the equilibrium in a reaction?
*Changing concentration of reactants or products
*Changing the temperature
*Changing the pressure of gases
Does a catalyst alter the position of the equilibrium?
Adding a catalyst does not affect the position of the equilibrium, but equilibrium is achieved faster.
The equation for concentration in an equilibrium reaction?
Kc = [C]c [D]d / [A]a [B]b
If Kc is less than 1?
The reactants concentration is greater than the products.
If Kc is 1?
The reactants and products concentration is equal.
If Kc is more than 1?
The products concentration is greater than the reactants.
What is the units for concentration?
moldm-3
How to convert cm into dm?
x10-3.
What is an acid?
Donates a proton during a reaction.
What is a base?
Accepts a proton during a reaction.
What is an alkali?
A base that dissolves in water.
What differentiates strong and weak acids?
A strong acid fully disassociates in an aqueous solution whereas a weak acid only partially disassociates.
What differentiates concentrated and dilute acids?
A concentrated acid consists of a large quantity of acid and a small quantity of water, whereas a dilute acid contains a large quantity of water and a small quantity of acid.
How to find pH?
pH = -log10[H+]
How to find the concentration in pH calculations?
[H+] = 10-pH
What universal indicator colour is shown with an acid?
Red, orange and yellow (pH 0-6).
What universal indicator colour is shown with an neutral solution?
Green (pH 7).
What universal indicator colour is shown with an alkali?
Blue and purple (pH 8-14).
What is a standard solution?
A solution whose concentration is accurately known.
What are the steps to performing a titration?
- Pour one solution into a burette using a funnel, remove the funnel and read the burette.
- Use a pipette to add a measured volume of the other solution into a conical flask and add indicator.
- Run the acid from the burette to the solution in the conical flask, swirling the flask.
- Stop when the indicator just changes colour.
- Read the burette again and subtract you initial from final reading to find your titre.
- Repeat titration until you have readings with 0.2cm^3 of each other and calculate a mean.
What would happen if you increase the acid in the titration?
You would get larger titres, therefore a smaller percentage error.
Why would you add indicator to your solution?
To show the end point.