Effects On Reactions Flashcards
Using universal indicator
Substance tested is dissolved in water, a drop of it is then placed onto PH paper
OR
A drop of universal indicator is dropped into the tested substance
A gas can be tested using damp PH paper
Universal indicator
Made of 6/7 indicators that change colour at different PH levels
Supplied as : a solution in ethanol / paper dipped in it and dried
Bases
Chemical opposite to alkalis
Alkalis
Bases soluble in water
Often more harmful than acids
8-14 PH
Neutral
Neither acidic or alkaline
7
Acids
0-6
Titration
Method of finding the volume of a solution required to react with a certain volume of another
Acid alkali titration
How much acid to neutralise an alkali
Acid-alkali titration method
Out 25.0 cm^3 of alkali solution into a flask
Few drops of methyl orange added
Note reading of acid in a burette
Add acid to alkali until indicator changes colour
Note final acid reading in burette
Substrate initial reading from final
-> Amount of acid required to neutralise 25.0cm^3 of the alkali
State of division
the smaller the pieces of solid -> the larger the overall surface area
More particles of the solid exposed to the other reactants
Grinding the solid to a powder has the most dramatic effect
Temperature of reaction
Increases average kinetic energy of the reactant particles
More of the collisions that take place will have the necessary activation energy to react
More successful reactions per second
Concentration of reactants
Increases the number of reactants
Reacting particles will collide more often
More successful collisions per second
Factors that affect rate of reaction
The concentration of a reaction
Temperature at which the reaction takes place
State of division of a solid reactant
Rate of reaction
Change of concentration of a reactant / time
Rate of reaction depends on
Concentration not amount
Particles must collide for a reaction to occur
Colliding particles must have enough energy to react
(activation energy) (successful collisions)
To increase the rate, the frequency of successful collisions must increas
Controlling the equilibrium
If forward reaction is exothermic
Backwards reaction is endothermic
More product
Equilibrium shift to the right
More reactant
Equilibrium shifts to the left
Dynamic equilibrium features
Rate of forward reaction = rate of backwards reaction
Amount of reactants and products remain constant
Dynamic equilibrium
If a reversible reaction is carried out in a closed reaction container
Then the reaction is able to reach a position of Dynamic equilibrium
Ammonia dynamic equilibrium
Hydrogen + nitrogen Ammonia
Ammonia can’t escape, will decompose into hydrogen + nitrogen
Rate of forward reaction will stop the rate of backwards reaction
They will then become equal
Copper (ii) sulfate crystals dynamic equilibrium
Copper (ii) sulfate crystals heated in a test tube
Crystals turn to powder, water collects on top
Crystals -> hydrated copper (ii) sulfate
Contains water of crystallisation
Heated to lose this water
->turns to Anhydrous copper (ii) sulfate
Reaction is reversible
Catalyst
A substance that increases the rate of reaction of a chemical reaction, but it is chemically unchanged at the end
Allow lower temperatures / pressures to be used
What catalysts do
Provide an alternative pathway for the reaction
This pathway has a lower activation energy
More of the collisions taking place will have the necessary activation energy
More successful collisions per second
Exothermic
- enthalpy
Energy given out
Rise in temperature
Endothermic
+enthalpy
Energy taken in
Fall in temperature
Heat given out
Mass of solution x specific heat capacity of solution x temperature rise
What is an acid
An acid is a substance that dissolves in water to produce hydrogen ions
A salt compound
Hydrogen ions (from dissolved acid) replaced by Ammonium or metal ions
You must react the dilute acid with what to replace the hydrogen ions by a metal ion
Metal
Base
metal carbonate
Litmus paper turns red
O-5
Acid
Litmus turns purple
5-8
Neutralish
Litmus turns blue
8-14
Alkali
Methyl orange turns red
0-3
Very Alkali
Methyl orange turns orange
3-5
Fairly acidic
Methyl orange turns yellow
5-14
Neutralise to alkaline
Phenolphthalein turns colourless
0-10
Acidic to neutralish
Phenolphthalein turns red
10-14
Very alkaline
Equilibrium
Endothermic
Shifts to right
Equilibrium
Exothermic
Shifts to left
Equilibrium pressure
Makes equilibrium shift to the area with the less particles
