Chemistry notes
Topic 1:
• Particles
• Everything is made up of particles
• First observed by Robert Brown (1827)
• Discovered that particles moved randomly
• This is now called Brownian motion
• Ex.
1. When cooking, smells di use in the room -> tiny particles spread because they
are bombarded by air molecules
• Particles mixing and spreading by colliding with many particles is called di usion
• Smallest particles (cannot be broken further) -> atoms
• Particles which consist of two or more atoms -> molecule (water)
• Groups of atoms which carry a charge -> ions
• States of matter
• Solid
• Particles don’t move -> only vibrate
• They have a very strong intermolecular attraction
• Keeps them in an ordered arrangement
• Liquid
• Particles move freely -> change shape
• Particles have too much energy for the intermolecular attraction to keep them
together
• Causes the substance to move around freely
• Gas
• Particles move extremely freely -> less dense
• Gas particles have more energy
• Meaning they move quicker
• Higher the temperature of the gas -> more energy
• Gasses always exert pressure
• In a ballon the particles inside bang against the balloon -> creating pressure
• Depends on the volume of container and temperature
• Increasing temperature increases pressure
• Compressing the volume of the container causes particles to move closer
• Water can be all three
• Various substances can change state
ff ff
, • Changes of state
• Sublimation
• Iodine is a substance which undergoes sublimation
• Di usion
• De nition
• Di usion is the movement of particles from a High
concentration (level) to a low concentration.
• Examples
• In our body oxygen and carbon dioxide are di using all
the time -> keeping us alive
• Rate of di usion depends on two factors:
• Mass of particle
• Higher the mass -> slower the rate of di usion
• Temperature
• Higher the temperature -> quicker the di usion
Topic 2:
• Mixture
• Contains more than one substance
• Ex.
• Air is a mixture of nitrogen, oxygen and CO2
• Solution
• Final product (solute + solvent = solution)
• Water (solvent) and salt (solute)
• Some substances dissolve in water
• White solid -> transparent solution
• Salt
• Coloured solid -> coloured solution
• Copper sulfate
• Soluble solids
• Dissolves
• Salt in water
• Sugar
• Solid disappears
• Solution is see-through (coloured or uncoloured)
• Saturated
• A substance which cannot dissolve no more solute at that temperature
• Insoluble solids
• Does not dissolve
• Sand in water
• Flour
• Solid is still visible or the solution is cloudy
Solubility of KBs
INFLUENCE OF WATER TEMPERATURE ON DISSOLVED POTASSIUM
BROMINE
VARIABLES
Independent (changes)
Temperature (°C), 25, 40, 60, 80
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,Dependent (measure)
Number of spatulas
Control (keep consistent)
Volume of water is 10ml (measuring cylinder)
Level of KBr on spatula
PREDICTION:
We hypothesise that increasing the temperature of the water will help the solubility of the solution,
as increasing the heat will allow particles to accumulate more energy, making them move faster
allowing them to change from a high concentrated area to a low concentrated area quicker.
METHOD:
1. Measure 10ml of water (measuring cylinder)
2. Heat up boiling tube to 25°C
3. Place water in boiling tube
4. Place spatulas of KBr
5. Stir for 20 seconds
6. Repeat experiment with di erent temperature
RISK ASSESSMENT
• Wear glasses
• Do not throw substance
• Stir precariously using glass stick
• Do not inhale the substance
• Be precautious when walking around
Temperature of water (°C) Number of spatulas
25 6
40 8
60 11
80 12
GRAPH
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, CONCLUSION
In conclusion, we can state that our hypothesis was correct since increasing the temperature of
the water helps substances be more soluble. However, as we can see from our graph, it is not
linear, in fact at 40°C the number of spatulas of KbR per 100g of water were 8 whilst at 80°C s
they were 12. This shows that there is not a xed ratio between the mass of the KbR and the
temperature of the water.
EVALUATION
Throughout the experiment there have been various imperfections which could be improved for
the following time. Firstly, we should have repeated each temperature 3 times, thus improving the
precision of the results. We could also have used a digital thermometer instead of an analogue
one as they are more accurate and cancel out the human error. Sticking to a limited time frame for
each temperature would have also made the experiment more fair, as some trials got more time
than others, allowing more KbR to dissolve. Slowly heating the water would have made the
experiment much more precise as it would have been more di cult to overshoot the desired
temperature, which would obviously have a drastic impact on the results.
• Purity
• De nition
• Substance consists only of one element or one compound
• A mixture consists of two or more di erent substances, not chemically joined
together
When the substance is pure -> When the substance is impure ->
very speci c freezing point freezes at any temperature in that range
Separating salt and sand from rock salt
METHOD
1. Add 5 spatulas of rock salt to 30ml of water
2. Stir using a glass rod to make sure all the salt dissolves
3. Filter the solution to remove the insoluble solid using the lter funnel, lter paper and a conical
ask
4. Pour the solution in the evaporating dish
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fi ff fi fi ffi fi
Topic 1:
• Particles
• Everything is made up of particles
• First observed by Robert Brown (1827)
• Discovered that particles moved randomly
• This is now called Brownian motion
• Ex.
1. When cooking, smells di use in the room -> tiny particles spread because they
are bombarded by air molecules
• Particles mixing and spreading by colliding with many particles is called di usion
• Smallest particles (cannot be broken further) -> atoms
• Particles which consist of two or more atoms -> molecule (water)
• Groups of atoms which carry a charge -> ions
• States of matter
• Solid
• Particles don’t move -> only vibrate
• They have a very strong intermolecular attraction
• Keeps them in an ordered arrangement
• Liquid
• Particles move freely -> change shape
• Particles have too much energy for the intermolecular attraction to keep them
together
• Causes the substance to move around freely
• Gas
• Particles move extremely freely -> less dense
• Gas particles have more energy
• Meaning they move quicker
• Higher the temperature of the gas -> more energy
• Gasses always exert pressure
• In a ballon the particles inside bang against the balloon -> creating pressure
• Depends on the volume of container and temperature
• Increasing temperature increases pressure
• Compressing the volume of the container causes particles to move closer
• Water can be all three
• Various substances can change state
ff ff
, • Changes of state
• Sublimation
• Iodine is a substance which undergoes sublimation
• Di usion
• De nition
• Di usion is the movement of particles from a High
concentration (level) to a low concentration.
• Examples
• In our body oxygen and carbon dioxide are di using all
the time -> keeping us alive
• Rate of di usion depends on two factors:
• Mass of particle
• Higher the mass -> slower the rate of di usion
• Temperature
• Higher the temperature -> quicker the di usion
Topic 2:
• Mixture
• Contains more than one substance
• Ex.
• Air is a mixture of nitrogen, oxygen and CO2
• Solution
• Final product (solute + solvent = solution)
• Water (solvent) and salt (solute)
• Some substances dissolve in water
• White solid -> transparent solution
• Salt
• Coloured solid -> coloured solution
• Copper sulfate
• Soluble solids
• Dissolves
• Salt in water
• Sugar
• Solid disappears
• Solution is see-through (coloured or uncoloured)
• Saturated
• A substance which cannot dissolve no more solute at that temperature
• Insoluble solids
• Does not dissolve
• Sand in water
• Flour
• Solid is still visible or the solution is cloudy
Solubility of KBs
INFLUENCE OF WATER TEMPERATURE ON DISSOLVED POTASSIUM
BROMINE
VARIABLES
Independent (changes)
Temperature (°C), 25, 40, 60, 80
ff
fffi ff ffff ff
,Dependent (measure)
Number of spatulas
Control (keep consistent)
Volume of water is 10ml (measuring cylinder)
Level of KBr on spatula
PREDICTION:
We hypothesise that increasing the temperature of the water will help the solubility of the solution,
as increasing the heat will allow particles to accumulate more energy, making them move faster
allowing them to change from a high concentrated area to a low concentrated area quicker.
METHOD:
1. Measure 10ml of water (measuring cylinder)
2. Heat up boiling tube to 25°C
3. Place water in boiling tube
4. Place spatulas of KBr
5. Stir for 20 seconds
6. Repeat experiment with di erent temperature
RISK ASSESSMENT
• Wear glasses
• Do not throw substance
• Stir precariously using glass stick
• Do not inhale the substance
• Be precautious when walking around
Temperature of water (°C) Number of spatulas
25 6
40 8
60 11
80 12
GRAPH
ff
, CONCLUSION
In conclusion, we can state that our hypothesis was correct since increasing the temperature of
the water helps substances be more soluble. However, as we can see from our graph, it is not
linear, in fact at 40°C the number of spatulas of KbR per 100g of water were 8 whilst at 80°C s
they were 12. This shows that there is not a xed ratio between the mass of the KbR and the
temperature of the water.
EVALUATION
Throughout the experiment there have been various imperfections which could be improved for
the following time. Firstly, we should have repeated each temperature 3 times, thus improving the
precision of the results. We could also have used a digital thermometer instead of an analogue
one as they are more accurate and cancel out the human error. Sticking to a limited time frame for
each temperature would have also made the experiment more fair, as some trials got more time
than others, allowing more KbR to dissolve. Slowly heating the water would have made the
experiment much more precise as it would have been more di cult to overshoot the desired
temperature, which would obviously have a drastic impact on the results.
• Purity
• De nition
• Substance consists only of one element or one compound
• A mixture consists of two or more di erent substances, not chemically joined
together
When the substance is pure -> When the substance is impure ->
very speci c freezing point freezes at any temperature in that range
Separating salt and sand from rock salt
METHOD
1. Add 5 spatulas of rock salt to 30ml of water
2. Stir using a glass rod to make sure all the salt dissolves
3. Filter the solution to remove the insoluble solid using the lter funnel, lter paper and a conical
ask
4. Pour the solution in the evaporating dish
fl fi
fi ff fi fi ffi fi
