Hello, this time I am just focusing on the main points so I can finish faster and you can learn only the important things.
PHYSICAL CHARACTERISTICS OF WATER:
Water exists in three forms:
 |
| SOLID as in ICE |
 |
| LIQUID as in WATER |
 |
| GAS as in STEAM/WATER VAPOUR |
- Freezing point of water is 0°C
- Boiling point of water is 100°C
- Ice is less dense than water, so it floats on water.
- Water is a poor heat and poor electrical conductor.
Impurities of water
- Salt water and sea water has a HIGHER BOILING point and a LOWER FREEZING point.
- Impurities of water increase the density of water. For example, sea water contains salt so people can float easier in sea water compared to pure water.
Compostion of water
Water is a COMPOUND (made up of two HYDROGEN atoms at the CATHODE(-) and one OXYGEN atom at the ANODE(+) )
Evaporation of water
Water evaporates at any temperature below 100°C. Factors that affects the rate of evaporation:
Humidity of air-The higher the humidity(that is the amount of water vapour in the air), the lower the rate of evaporation
Temperature of surroundings-The higher the tempature, the higher the rate of evaporation.
Surface area of water-The larger the surface area, the higher the rate of evaporation.
Air movement-When there is moving air(i.e wind), the rate of evaporation will be higher.
Solution and Solubility
The SOLUTE is the substance you dissolve in the SOLVENT to get a SOLUTION.
Example:
Solute- Salt
+
Solvent- Water
=
Solution-Salt solution
All solutions are homogeneous, that is the solution will appear uniform(same) in color.
Mixing sand into the water does not make a solution because the salt does not dissolve and you can still see the sand.
Dilute, Concentrated, and Saturated Solutions.
There are three types of solutions with differences,
Dilute solutions-contains a small amount of solute, thus can dissolve a lot more.
Concentrated solutions-contains more solute than dilute solutions, thus can still dissolve a little more.
Saturated solutions-contains the maximum amount of solute, thus cannot dissolve anymore.
Solutions and Suspensions
Ill use two examples to explain solutions and suspensions and will compare two of them to show the differences:
For solutions I will use salt solution and for suspensions I will use sand and water:
This is the salt solution This is your sand and water.
1. Solution is a mixture which the solute dissolves in the solvent whereas a suspension is a mixture in which particles are suspended in a liquid or gas. PROOF: The salt dissolved in the water so you can't see it, the sand is suspended in the water so it is not dissolved so you can see it.
2.A solution contains dissolved substances but a suspension contains insoluble(cannot dissolve) substances. PROOF: The salt has dissolved in the water but the sand have not and cannot dissolve in the water.
3. A solutiion is transparent and clear, allows light to pass through, a suspension is opaque and cloudy and does not allow much light to pass through, in the sand solution although its not cloudy, but the sand is opaque. PROOF: obviously you can see the differences in the pictures above.
4. A solution is homogeneous or uniform(meaning it appears in the same colour) and a suspension is non-homogeneous/heterogeneous(meaning you can see the difference of colour). PROOF: In the salt solution you can only see clear water whereas you can see sand and water clearly seperated.
5. The size of particles in a solution is small and well dispersed(scattered) meaning there is space between the particles and the particles in a suspension is large and not well dispersed, meaning there is few space between the particles and are arranged closely.
6. When left to stand, no sediment is seen in the solution, but solid particles(i.e sand in the example) will settle to the bottom or float at the surface in a suspension.
7. When a solution is filtered, no residue is left on the filter paper; when a suspension is filtered residue is left on the filter paper.
Rate of Dissolving
Factors that affect rate of dissolving:
-Size of the solute particles, the smaller the size of the solute particles, the faster the solute dissolves in the solvent(e.g fine sugar dissolves faster in water compared to sugar cubes)
-Rate of stirring the solvent-the faster the rate of stirring, the faster the solute dissolves in the solvent
-Temperature of the solvent-The higher the temperature of the solvent, the faster the solute dissolves in the solvent.
Last but not least in this part, WATER is the UNIVERSAL SOLVENT
The SOLUTE is the substance you dissolve in the SOLVENT to get a SOLUTION.
Example:
Solute- Salt
+
Solvent- Water
=
Solution-Salt solution
All solutions are homogeneous, that is the solution will appear uniform(same) in color.
Mixing sand into the water does not make a solution because the salt does not dissolve and you can still see the sand.
Dilute, Concentrated, and Saturated Solutions.
There are three types of solutions with differences,
Dilute solutions-contains a small amount of solute, thus can dissolve a lot more.
Concentrated solutions-contains more solute than dilute solutions, thus can still dissolve a little more.
Saturated solutions-contains the maximum amount of solute, thus cannot dissolve anymore.
Solutions and Suspensions
Ill use two examples to explain solutions and suspensions and will compare two of them to show the differences:
For solutions I will use salt solution and for suspensions I will use sand and water:
This is the salt solution This is your sand and water.
1. Solution is a mixture which the solute dissolves in the solvent whereas a suspension is a mixture in which particles are suspended in a liquid or gas. PROOF: The salt dissolved in the water so you can't see it, the sand is suspended in the water so it is not dissolved so you can see it.
2.A solution contains dissolved substances but a suspension contains insoluble(cannot dissolve) substances. PROOF: The salt has dissolved in the water but the sand have not and cannot dissolve in the water.
3. A solutiion is transparent and clear, allows light to pass through, a suspension is opaque and cloudy and does not allow much light to pass through, in the sand solution although its not cloudy, but the sand is opaque. PROOF: obviously you can see the differences in the pictures above.
4. A solution is homogeneous or uniform(meaning it appears in the same colour) and a suspension is non-homogeneous/heterogeneous(meaning you can see the difference of colour). PROOF: In the salt solution you can only see clear water whereas you can see sand and water clearly seperated.
5. The size of particles in a solution is small and well dispersed(scattered) meaning there is space between the particles and the particles in a suspension is large and not well dispersed, meaning there is few space between the particles and are arranged closely.
6. When left to stand, no sediment is seen in the solution, but solid particles(i.e sand in the example) will settle to the bottom or float at the surface in a suspension.
7. When a solution is filtered, no residue is left on the filter paper; when a suspension is filtered residue is left on the filter paper.
Rate of Dissolving
Factors that affect rate of dissolving:
-Size of the solute particles, the smaller the size of the solute particles, the faster the solute dissolves in the solvent(e.g fine sugar dissolves faster in water compared to sugar cubes)
-Rate of stirring the solvent-the faster the rate of stirring, the faster the solute dissolves in the solvent
-Temperature of the solvent-The higher the temperature of the solvent, the faster the solute dissolves in the solvent.
Last but not least in this part, WATER is the UNIVERSAL SOLVENT
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