Physical Flashcards
Methyl orange
0-3 red
3-6 orange
6-14 yellow
Phenolphthalein
0-10 colourless
10-14 red
Acid def
A substance that dissolved in water to produce hydrogen ions (H+)
Litmus paper
0-4 red
5-8 purple
8-14 blue
Acid + metal
Salt + hydrogen
Acid+ metal carbonate
Salt + CO2 + water
When testing wait till no more bubbles form to show complete neutralisation
Acid + metal oxide
Salt + water
Acid + metal hydroxide
Salt + water
Solubility
Nitrates
All
Solubility
Chlorides
All but silver and lead
Solubility
Sulfates
All but barium, calcium and lead 2
Solubility
Sodium, potassium and ammonium salts
All
Solubility
Sodium, potassium and ammonium carbonates
All
Insoluble base + acid test
- heat acid
- add base a little at a time
- till excess
- filter (to remove access)
- hydrous? Heat till at least 2/3 of the water had left
- leave to crystallise in a warm place
Remove crystals and then dry
Soluble base + acid test
- aqueous solution of alkali into conical flask and add indicator
- add dilute acid until change in colour
- add powdered charcoal and shake to remove colour
- filter to remove charcoal
- obtain crystals from filtrate
Preparation of insoluble salts
Precipitation reactions!
(Insoluble solid made by chemical reaction in an aqueous solution)
- mix 2 aqueous solution
- one of then contains +ve ion other
- ve ion
- filter
- with the filtrate wash with distiller water to remove traces of the solution formed
- leave to dry
Make ammonia
Whenever ammonium salt reacts with an acid
Indicator needed to decide whether or not reaction is complete
- acid alkali titration
Acid- alkali titration
To find given volume of acid required to react exactly with the given volume if alkali
- use pipette add 25cm3 of alkali solution into conical
- add few drops of indicator
- put acid into a burette and note initial reading
- add acid till change in colour
- not how much was added
- repeat without indicator but the exact volume
Exothermic
Energy given out
Rise in temp
——–\______
^H = negative
Endothermic
Energy taken in
Fall in temp
_____/———
^H = positive
Measure heat change
Place acid into polystyrene cup
Record temp of acid
Tip excess powder into acid
Measure and record highest Reno reached by mixture
- rise in temp
- heat given out
Heat given out equation
Mass of solution x specific heat capacity x temp rise
E = mc^T
Bond energies
Energy required to break a bond
Bond energy measured in…
Kj per mol
KJ/mol
Breaking bonds
Takes in energy
Endothermic process
Making bonds
Gives out energy
Exothermic process
How to calculate /\ H
Bonds broken- bonds made
Rate of reaction def
Rate = change of conc of reactant / time
Factors there affect rate of reaction (3)
Conc of reactant
Temp at which reaction takes place
State of division
Conc rates
Increasing conc increases no of particles in a given volume hence increasing the frequency of collisions
This means there will be more successful collisions per second
Same as increasing pressure
Temp rates
Increased average kinetic energy of the reactant particles therefore more of the collisions will have the required activation energy needed to be successful
State of division rates
Smaller the pieces the larger the surface area
More particles exposed to other reactant
More successful collisions per sec
Most effective in powder form
Effect of catalyst
Provides an alternate pathway for the reaction
Has a lower activation energy than the original pathway
Means that more of the collisions will have the necessary activation energy
Catalyst def
A substance that increases the rate of a chemical reaction but is chemically unchanged at the end of the reaction
Reaction that goes both ways
Reversible
Example of a reversible reaction
Copper 2 sulfate crystals Hydrous and anhydrous Heating and adding water Water of crystallisation From white to blue with water
2nd example of reversible reaction
Heating ammonium chloride
White solid crystals -> colourless gases
NH4Cl -> HCl + NH3
The gases rise and cool to form back
Dynamic equilibrium
If reaction reversible is carried out in a closed container then it is possible for the reaction to reach a position of dynamic equilibrium
When rate if forward is equal to rate of backward
Amounts of reactants and products remain CONSTANT
Properties relying on amounts of reactants/ products remain constant (colour or pressure)
Shift the position of equilibrium
To the right
To the left
Equilibrium increase pressure
Shifts in direction that produces the smaller number of molecules of gas
Equilibrium increase in temp
Moves in endothermic direction
Equilibrium decrease in temp
Moves in Exothermic direction
Equilibrium model answers
Temperature
The equilibrium shifts to the (left/right) because the (forward/backward) reaction is Exothermic
Equilibrium model answer
Pressure
The equilibrium shifts to the (left/right) because there are fewer molecules of gas in the (left/right)
Equilibrium model answer
Adding or removing substances
The equilibrium shifts to the (left/right) because the (forward/backward) reaction uses/produces the _____
Equilibrium
Increasing temp will favour the….
Endothermic reaction because this reaction needs heat to occur
Decreasing will favour Exothermic because less heat means that the endothermic reaction can’t happen as much
