Physical Chemistry (Acids, Alkalis, Salts, Energetics, Rates Of Reaction, Equilibria) Flashcards
Universal indicator:
Acid:
Neutral:
Alkali:
Strongly acidic: Red Weakly acidic: Orange Neutral: Green Weakly alkali: Blue Strongly alkali: Purple
Litmus paper:
Acid:
Neutral:
Alkali:
Acid: Red
Neutral: Purple
Alkali: Blue
Phenolphthalein:
Acid:
Alkali:
Acid: Colourless
Alkali: Pink
Methyl Orange:
Acid:
Alkali:
Acid: Red
Alkali: Yellow
Ph 0 =
Strongly acidic
Ph 14 =
Strongly acidic
An acid is a source of ____________ ions
Hydrogen ions (H+)
An alkali is a source of ____________ ions
Hydroxide ions (OH-)
The reaction between an acid and an alkali (or an acid and a base) is known as:
Neutralisation
Acid + Base–>
Acid + Base–> Salt + Water
Acid + Metal Oxide–>
Acid + Metal Oxide–> Salt + Water
Acid +Metal Carbonate –>
Acid +Metal Carbonate –> Salt + Water + Carbon dioxide
If the acid is hydrochloric acid, the salt will be a metal ___________
Chloride
If the acid is sulfuric acid, the salt will be a metal ___________
Sulfate
If the acid is nitric acid, the salt will be a metal ___________
Nitrate
Everything is soluble except for:
Carbonates (Except for sodium potassium and ammonium)
Barium sulfate
Calcium sulfate
Silver chloride
How do you make a soluble salt using acids
Add an insoluble base
Describe making a soluble salt using acids + insoluble bases
Add the insoluble base to the acid. The solid will dissolve. The acid had neutralised when the excess solid sinks to the bottom of the flask.
You can then filter out the excess solid to get the salt solution.
For pure, sold crystals of salt, evaporate off the water.
How do you make soluble salts from an alkali
Titrations
How do you make insoluble salts
Precipitation reaction
Describe a precipitation reaction:
Pick two solutions with the ions you need and mix them
How do you do a titration
- Add (25cm3 of) alkali to a conical flask alongside indicator
- Meanwhile, fill a burette with acid (below eye level)
- Add the acid to the alkali (using a burette)
- The indicator will change colour when neutralisation takes place
- Record the volume of acid used to neutralise the alkali
- Repeat
What four things does a rate of reaction depend on:
Temperature
Concentration (pressure)
Catalyst
Size of particles (surface area)
Rate of reaction equation
Rate of reaction = amount of product formed (or reactant used) / Time
What are the 3 ways the speed of reaction can be measure
Precipitation
Change in mass
Volume of gas given off
How does a catalyst speed up a reaction
By providing an alternative pathway with lower activation energy
What is activation energy
The minimum energy needed by reacting particles for the reaction to occur
Chemical reactions in which heat is given out are known as ______________
Exothermic
Chemical reactions in which heat is taken in are known as ______________
Endothermic
Energy is _____________ to break existing bonds - so bond breaking is an _____________ process
Supplied
Endothermic
Energy is _____________ when new bonds are formed - so bond formation is an _____________ process
Released
Exothermic
If the value of enthalpy change is negative, the reaction is ______thermic
Exothermic
If the value of enthalpy change is positive, the reaction _____thermic
Endothermic
In an exothermic energy level diagram, the reactants are __________ the products
Above
In an endothermic energy level diagram, the reactants are __________ the products
Below
What is a reversible reaction
Where the products of the reactions can themselves react to produce the original reactants
Describe the thermal decomposition of ammonium chloride
When heated, ammonium chloride breaks down into ammonia and hydrogen chloride. When the ammonia and hydrogen chloride cool, they re-form to make ammonium chloride
What does equilibrium mean
That the relative quantities of reactants and products will reach a certain balance and stay there
In a reversible reaction, the position of equilibrium depends on the ____________ and ____________ of the reacting mixture
Temperature and pressure
What is the effect of increasing temperature on equilibrium.
What is the effect of decreasing temperature on equilibrium
If you increase the temperature, endothermic reaction will increase (to use up extra heat)
If you decrease the temperature, exothermic reaction will increase (to give out more heat)
What is the effect of increasing pressure on equilibrium
What is the effect of decreasing pressure on equilibrium
If you increase the pressure, it will encourage the reaction which produces fewer molecules of gas
If you decrease the pressure, it will encourage the reaction which produces more molecules of gas
What is dynamic equilibrium
The reactions are still taking place in both directions, but the overall effect is nil because they cancel each other out
