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Transcript of Science PBL
Part H: Fluid Pressure / Pneumatics and Hydraulics
Part C: Dissolving
Part E: Flow Rate and Viscosity
Part G: Buoyancy
1.What needs to happen for gas to be compressed and explain why other states of matter can’t be compressed as well?
2.What are some advantages of gas compression? Give a couple of examples.
3.Explain how pressure changes with altitude and also explain what happens when you go underwater.
4.Explain compression and the balance of forces. Give a couple of examples to show this.
5.Explain what hydraulics and hydraulic systems are and give an example of hydraulics being used to do work.
6.Explain what pneumatics is and how a pneumatic system works. Also give a couple of examples of pneumatics.
Part F: Density
1.What is density?
2.Name and explain the density of the three states of matter in order from most dense to least dense. What are two exceptions to this rule? Explain this.
3.Use the Particle Model of Matter to help explain what happens to the density of a substance when you heat it. Explain how would pressure affect density?
4.How do we measure density?
Part B: Classifying Matter
Part A: Matter on the Move
1.What is the Particle Model of Matter (there are five points to this)?
2.What are the 3 states of matter and give at least 3 characteristics for each state?
1.Explain what dissolving is and why it happens.
2.Explain the following: solubility, saturated, supersaturated, unsaturated, solvent and solute.
3.What is the Universal Solvent?
4.How does the Particle Model of Matter help explain dissolving?
5.Explain what rate of dissolving means and name and explain three ways we can increase the rate of dissolving of a substance.
1.What does viscosity and flow rate mean?
2.Talk about two different consumer products and explain how viscosity is important for it.
3.Explain how the viscosity of liquids and gasses change with temperature change.
1.Explain what buoyancy is and what another name form buoyancy is. Why does it have this alternate name?
2.Talk about three things that rely on buoyancy to work.
3.What is average density and explain how it relates to buoyancy and explain how we reduce or increase the average density on a ship? Also explain why average density is important to us and talk about a couple of examples of average density working in real life.
4.Explain what Archimedes Principle is and show a video to help explain it.
5.Explain how buoyancy and density are related.
1.Explain how matter is classified into Pure Substances (elements and compounds) and Mixtures (solutions, mechanical mixtures, suspensions and colloids). Make sure to give two characteristics for each part.
1. Talk about two of Earth’s Mixtures and how they are separated.
Part D: Separating Earth’s Mixtures
There are five points in the Particle Model of Matter, which are the following:
-all substances are made up of tiny particles
-all particles in a pure substance are the same. Different pure substances are made up of different particles
-the particles have spaces between them
-the particles are always in motion--vibrating, rotating and (in liquids and gases) moving from place to place. The speed are particles increases when temperature increases and speed decreases when temperature decreases
-the particles in a substance are attracted to one another. The strength of the attractive force depends on the type of particle
-has a definite shape and volume
-solids are greatly affected by gravity and will move to the lowest point
-solids can be ground into small pieces until they can be poured...but each piece is still a solid and they pile up on each other and can't flow
-has a definite volume but no definite shape
-particles have enough energy to pull away from each other...therefore they can slide (flow) around each other while still vibrating close to each other in small groups
-liquid are packed tightly enough together that they are affected by gravity. Liquids will always flow to the lowest point
-has neither a definite shape or volume
-most gases seem invisible because there is so much space between particles
-most gases do not flow to the lowest point as do liquids and solids. Because gas particles are spread out so much, they move in all directions, sometimes against gravity and remain suspended
• Elements- Pure substances are found in the Periodic Table of Elements. These are the only pure substances that we know of and all of the substances in the table are an element. Any one of the simplest chemical substances that cannot be decomposed in a chemical reaction. Chemical elements consist of atoms which have the same number of protons. Each element has distinctive atomic number.
• Compound- The elements in the periodic table are combined together to create compounds. Compounds are made of two or more elements. Compounds have very strong chemical bonds and as the elements combine, they lose their individual characteristics. To form a compound chemical reaction is needed. Compounds cannot be separated by physical means.
• Homogeneous (Solutions) - is a mixture of 2 or more substances that has uniform properties (that appear as one). They only have one phase, they are uniform throughout, they are also known as solutions, and they can be separated with the differences between the physical properties of what it is made up of.
• Heterogeneous (Mechanical mixtures) - is a mixture of 2 or more substances that are visible. Heterogeneous mixtures can be separated by mechanical means such as using a filter or using your hands.
• Suspensions- are a mechanical mixture in which the components are in different states. That is settled overtime, and through the filtration we can obtained the suspension.
• Colloids-A heterogeneous mixture in which the particles do not settle. A colloid is defined by the size of the particles involved and it can’t be easily separated.
•Saturated- Combined with or containing all the solute that can normally be dissolved at a given temperature.
•Supersaturated- To cause (a chemical solution) to be more highly concentrated than is normally possible under given conditions of temperature and pressure.
•Unsaturated- solute can be still dissolved in the solvent (a solution that is not saturated).
• Solvent- A substance in which another substance is dissolved, forming a solution.
•Solute- a substance that dissolved into solvent.
Water is called the Universal Solvent because it can dissolve so many substances.
The rate of dissolving is how fast a solute dissolves in a solvent.Some things that can speed up the rate of dissolving are:
-agitation helps the solutes dissolve faster
-smaller pieces dissolve faster than larger pieces of a substance
-in many substances the rate of dissolving increases as the temperature increases
We will be telling you how to separate; gold from gold ore, and sea salt from water.
Gold is a solid, and is very hard to find. They are found in mines, etc. Extracting Gold:
-gold ore (rock with gold in it) is crushed and mixed with water to create suspension
-chemicals are added to make the gold dissolve and only the gold will dissolve
-the dissolved gold can then pass through a filter,while all the other materials are caught in the filter
-the gold is then released from the solution and settles to the bottom and is collected
Sea salt is salt that comes from the sea. It isn't that hard to collect sea salt, you just evaporate the water. Collecting Sea Salt:
-sea salt is collected in large open pools
-the water evaporates and leaves the salt behind in the pool
•A liquid’s thickness or thinness is called viscosity. A thicker fluid would be more viscous
•The time it takes a fluid to flow from one point to another is called a fluid’s flow rate
Density is the amount of mass in a certain unit, volume of a substance. In a substance that is more dense, the particles are more "crowded" together.
•Solids – The particles in a solid are tightly packed together; therefore solids are the densest state of matter.
•Liquids – The particles of a liquid are more spread out than solids but less than gas. Therefore, liquids are less dense than solids but more dense than gas.
•Gas – Gas particles are the most loosely packed together so gases are the least dense state of matter.
•Mass – The amount of matter in a substance
•Volume – The amount of space occupied by a substance
•This Formula is used to measure density: Density = Mass / Volume (D = M / V)
•Buoyancy is the ability to float in a liquid or to rise in a fluid.
•Buoyancy is also known as the buoyant force…it is the upward force exerted on objects submerged in fluids (gas or liquid).
Here are 3 examples of things that rely on buoyancy to work:
-moving nutrients in our bloodstream
-pollen floating through the air
-planes and boats transporting goods
The buoyant force of a liquid and gas depends on density. A liquid or gas that is more dense, can support more weight per volume than a liquid or gas that is less dense.
•The gas must be enclosed in a sealed container with strong walls so the molecules can distribute themselves through the container.
•There is so much space between gas particles, so even after they are compressed, there are spaces between the particles still exists so they still act like a gas.
•An external force is applied to the gas to push the particles together.
•Mechanisms that work because of the movement of a liquid, or the force exerted by a liquid within a closed system is called a hydraulic system.
•Hydraulics can be applied to engineering devices involving liquids, usually water or oil.
Hydraulics deals with such problems as:
•the flow of fluids through pipes or open channels
•the design of storage dams, pumps, and water turbines
•nozzles, valves, and jets, that control the flow of liquids
•Pneumatics is the study of pressure in gas.
•The operation of pneumatics is based on the fact that gas can be compressed.
•As gas is decompressed, the particles start to move apart suddenly, creating a steady force to perform tasks.
•Car tires gain their rigidity from the compression of the air inside them.
Forming a solution by mixing two or more materials is called dissolving
Dissolving happens because particles attract each other and they are always in motion vibrating and moving from side to side.
•Air pressure changes with altitude. As you go higher in the atmosphere the pressure gets lower. This happens because there are fewer particles above you pushing down. When swimming underwater there are more particles on us that are pushing down on us.
The Particle Model of Matter says:
the particles in a substance are attracted to one another. The strength of the attractive force depends on the type of particle
so particles that make a solution would have stronger attractions to each other, where as particles in mixtures would not have as strong of attractions to each other
it also says that the particles are always in motion,vibrating, or moving from side to side. So it is easier for them to mix together and the attraction between particles can work quicker
Oil Extraction from Oil Sands:
One method is to use steam and inject it underground
The steam heats the oil sands and makes the oil thinner or less vicious
Then the oil can be pumped out of the ground
Viscosity is important
If the nail polish is too thin then it will flow too fast and dry slow
And if the nail polish is too thick then it will flow slowly and dry too fast
As temperature of a liquid increases, the viscosity decreases meaning it can move quicker. As the temperature of a liquid decreases (gets colder), the viscosity increases meaning it will move slower.
As the temperature of a gas increases, the viscosity increases as there are more collisions between the gas particles. The increased collisions mean it is harder for the gas to move.
As the temperature of a gas decreases (gets colder), the viscosity decreases meaning it will move quicker
Gas can let out a counter force back when compressed. This is useful for:
Car tires – The tires push back against the weight of a car otherwise they would just collapse.
Air bags – They absorb the shock of a crash to protect passengers.
Shock absorbers in a vehicle – They absorb the force from hitting bumps in the road.
When a state of matter is heated, the particles speed up and spread out more. If they spread out more, then there is more space between the particles. This then means that as a state of matter is heated, its density decreases. If there is more space between particles in a substance, then the density is lower. Density of a substance stays the same as long as the temperature and pressure stays the same. If the temperature and pressure changes then the density changes.
If the average density (the total mass of the substance and everything on it divided by the total volume) is less than the density of the water then it will float. Average density is important and very useful to us because it helps objects that would sink, to float. It can also help floating objects to sink.
Examples: Life jackets on a person helps us float, it lowers our average density. The swim bladder in fish help them to sink and rise in the water.
The Archimedes Principle is the buoyant force acting on an object equals the weight of the fluid displaced by the object.
The particles are almost as close as possible so when a force is applied to them, they can't move much closer together.
Gas can be compressed because there is lots of space between particles.
Car tires- The tires push back against the weight of a car otherwise they would just collapse.
Air bags- They absorb the shock of a crash to protect passenger.
Balanced and unbalanced forces
If the inside of a container experiences lower pressure than the outside, the container would collapse. If the pressure is higher in the container than outside, than it would expand.