5.1 Notes What Makes Materials Dissolve?
When you stir sugar into a glass of water, it forms a homogeneous mixture. Forming a solution by mixing two or more
materials is called dissolving. Mixing materials together does not always make a solution. Some materials do not
dissolve.
Two new ideas for the Particle Theory of Matter:
1. Particles attract each other
2. Particles are always moving
Plus the two previous ideas:
~ All matter is made up of extremely tiny particles
~ Each pure substance has its own kind of particle different from the particles of other pure substances.
Why do some materials not dissolve?
Another way to say "sugar dissolves in water" is to say "sugar is soluble in water." Soluble means able to be
dissolved in a particular solvent. For example, sugar is soluble in water. The pulp in orange juice is not soluble;
however, and neither are the small droplets of fat in milk; these are insoluble. Insoluble means not able to be dissolved
in a particular solvent.
Solute: is the substance that dissolves in a solvent to form a solution.(sugar, salt, etc.)
Solvent: is the substance that dissolves a solute to form a solution.(water)
Chemical change: when a material has changed form and cannot go back to the original form.
Chapter 5 notes
5.1 Check Your Understanding
1. a) A solution is a special homogeneous mixture of two or more materials. The materials are evenly mixed
throughout, and you cannot see the different kinds of particles.
b) An example of a solution from the book is sugar and water. Other solutions not mentioned so far are bleach, glass
cleaner, cologne, and ink.
2. a) The solute in ocean water is salt.
b) The solvent is water.
3.
b)
c)
d)
a) Solutions that are gases are air, humid air, and naphthalene in air (mothballs).
Two solutions that are solids are brass and amalgam.
A solution where both solute and solvents are liquids is vinegar.
A solution of a gas in a liquid is soda water.
4. Fog is a heterogeneous mixture. The light from the headlights of a vehicle will scatter in fog, indicating a
suspension rather than a solution.
5. Both alcohol and water are needed to remove the grass stain. Dissolve the grass stain in alcohol, and then rinse the
alcohol and the grass stain out with water.
5.2 Notes: Water in the Environment
- 97% of the water on earth is in the oceans.
- Water is a good solvent.
- Water is a universal solvent.
- 2% of water is ice in the Arctic and 1% of water is fresh
- Water may contain many solutes; some safe, some not.
- Water mixes easily with salt materials and may appear discolored and/or cloudy.
- To extract salt from the sea water you have to leave it contained in direct sunlight to evaporte the water.
- Because the solute does not change state they are left behind when the solvent changes state.(usually gas)
Check Your Understanding 5.2
1. a) Distillation is a method used to separate the solute from the solvent in a liquid solution.
b) During distillation, the solution is heated and the particles of solute and solvent begin to move faster, separating and
moving away from one another. The particles of the solvent begin to escape into the air. As these particles are cooled,
they slow down and change back into a liquid.
2. Water that is found in nature is not always pure. Seawater is very salty and may contain other undissolved
materials. Fresh water may contain harmful organisms and dissolved substances.
3. In both systems, the solvent is being heated to change it into a gas, and then it is condensed into a liquid. As the solvent
is heated, the movement of the particles increases. The water particles eventuallly move away into the air and escape the
attraction of the salt particles. Both systems are used to produce pure or distilled water.
The solvent boils in the distillation system but not in the desert tent evaporator. Therefore the distillation system is a
faster method. As well, the particles are moving faster in the distillation system. It uses fuel to heat the solvent,
whereas the tent evaporator relies on the availability of heat from the Sun.
4. Some solutes that may be contained in a can of cola are caffeine, sugar (glucose, frutose), sodium benzoate, caramel,
carbon dioxide, phosphoric acid, aspartame, potassium citrate, and citric acid.
5. Rainwater is oft water since it lacks dissolved
minerals. Soft water produces more suds and is better for cleaning purposes. Soft water does not leave a scum.
6. a) As rainwater soaks into the soil, it dissolves minerals. When this water enters the river, it brings with it these
substances.
b) Hard water is perfectly safe for drinking.
c) Hard water interferes with the cleaning action of soap so that more soap is required. It also leaves sticky deposits on
clothing. Hard water causes problems in plumbing pipes because of the buildup of minerals. It will leave mineral
deposits in water-using appliances, such as dishwashers, showerheads, kettles, and humidifiers.
8. Such as environment would require a lot of bright sunlight and warm temperatures.
Activity
a) fertilizer added to
lawns and fields
b)dumped sewage
Effect
a)- introduces chemicals
into lakes and rivers
-increases algae growth
-lowers oxygen content
and affects fish
b) -contains organic waste
that uses up oxygen
c) salt on roads
c) -washesoff roadside and
flows into rivers and streams
-affects aquatic plants and
Animals
Activity
Effect
d) sanitary landfills
d)-allow pollutants and
contaminants to enter
ground water
-affect water supply
e)electric generating
stations
e)-return low-oxygen heated
water to rivers
-harm fish and other
aquatic life
Check Your Understanding 5.3
1. a) Examples could include soap, bubble bath, frozen juices, herbicides, derergent, plant fertilizer, and canned soup.
b) Products may be labelled as concentrate because they need to be diluted with water prior to use.
2. Maple sugar is made from maple syrup. Boiling off maple sap, a solution of sugar and water, makes the syrup.
Additional nutrients give the syrup and sugar a distinctive flavour.
Cane sugar comes from sugar-cane stalks that are cleaned, chopped, and shredded. This material is boiled in water
to dissolve the sugar.
3. a) Two end products of maple sap are maple syrup and maple sugar.
b) Four end prducts made from sugar cane or sugar beets are white sugar, golden brown sugar, dark brown sugar, and
molasses.
4. Fuel is needed to heat the solution of sugar and water.
5.
a) Filtration is a process used to separate larger, solid particles from a fluid
5. b) Filtration is used in maple syrup production to remove any impurities that could affect its appearance and
dlavour. In cane-sugar or beet-sugar production, filtration is used to remove any shredded bits, as well as impurities.
c) The other separation method is evaporation - a process in which liquid particles change to gas particles at the
surface of the liquid.
6. More steps are required to produce cane sugar because the sugar is not as accessible. The cane needs to be chopped
and shredded to allow water to dissolve the sugar. The sap in maple syrup is already in a solutiojn and contains the
sugar. The water simply needs to be boiled off.
7. a) Filtration is used in making coffee to separate the grounds from the water.
b) The tiny holes hold back the grounds but let the coffee-infused water through.
c) The material in a tea bag allows the smaller particles of water to pass through but keeps the larger particles of tea
inside the bag.
Chapter 5 Review
1. a) In a sugar and water solution, the sugar is the solute, and the water is the solvent
b) Substances that dissolve in a liquid are soluble in that liquid.
c) Iron is insoluble in water.
d)Distillation is a way of recovering the solute and the solvent from a solution.
e) When steam is cooled, it changes back into water. This process is called condensation.
f) Both evaporation, and condensation take place during the process of distillation.
g) You need to desalinate seawater to make it drinkable.
h) If a solution contains a lot of solute in a small amount of solvent, it is concentrated.
i) Weak solutions are also called dilute.
2. SOLUTION
SOLUTE
SOLVENT
soda water
carbon dioxide
water
hard water
minerals
water
air
oxygen
nitrogen
3. a) Whe the solute dissolves, the particles of the solute are more attracted to the solvent particles than to the other
solute particles.
b) If the attraction of the solute particles to similar particles is greater than their attraction to different particles, then
the substance will not dissolve.
5. a) The particles of a grain of plant fertilzer stay together because the particles are attracted to one another.
b) The fertilizer particles dissolve in water because the water particles work together to pull apart or attract them. As
the water particles dissolve more of the fertilizer particles, more or the remaining fertilizer particles are exposed to the
water.
c) The fertilizer willnot dissolve in oil because the particles of fertilizer are more attracted to each other thatn they are
to the oil particles.
6. SOLUTION
SOLUTE
SOLVENT
instant coffee
coffee crystals
water
soda water
carbon dioxide
water
ocean water
salt
water
air
oxygen
nitrogen
brass
zinc
coppper
7. In a dilute sugar and water solution, the attractive force of the water particles on the sugar particles is strong. If the
solution is concentrated, all of the attractive forces of the water particles are used up on the sugar particles that are
already dissolved.
8. a) The dishwater would need to be boiled to get the pure water from the mixture. The gas that escapes would need
to be collected and cooled to change the gas back into a liquid. This is called distillation.
b) This is not a practical method because of the high energy cost to recover such a small quantity of pure water.
9. a) Some human activities that are harmful to our water supply include adding fertilizers to fields and lawns,
dumping sewage, using salt on roads during the winter, dumping heated water from electric generating stations, using
pesticides and herbicides, and dumping pollutants from factories. Water is used in these activities because it dissolves
so many different materials.
12. To remove the sand from the water solution, pour the mixture through a filter. To remove the salt and fine
undissolved particles from the water solution, the mixture would need to be distilled.
14. The Dead Sea is the lowest body of water on Earth's surface. As a result, water flows into it but has no way of
flowing out. As the water in the sea evaporates, it leaves dissolved minerals behind, that is why the Dead Sea has six
times the amount of salt in it of any other ocean.
15. Fats and oils are not soluble in water but we can get them clean because the detergent gets between the grease
particles and prevents them from attracting one another. The particles become dispersed throughout the water and are
easily rinsed off the dishes.