The Scientific Method

A hypothesis is a statement that answers the question, or provide a tentative explanation to why the observed event occurred.

Variables: Independent, dependent & controlled variables.

Independent - is the variable which the experiment is designed to test.

Dependent - is the variable which the experiment is designed to measure.

Controlled - are the factors which must be controlled in the experiment so that they will not affect the outcome.

Step 1: Choosing the Best Science Project Topic 

• The project topics you consider should be things that interest and excite you.

So what excite you?

•  Think about something you like to do. What would you like to find out about it? Think about the who, what, when, and where of the activity. Who can you do the activity with?

• What were the interesting questions that you thought of when studying the various science module in Year 1 and Year 2 this year.

• After you have a general sense of what interests you, it is time to get specific.

• If you need help for ideas, visit the various videos in this site or do a search on Science Projects. Find ideas that line up with that general sense of what you have in mind and then choose the best topic for you.

Step 2: Choose the Best Topic for You 

• When choosing possible science project topics you should keep in mind that originality counts. Use the resources mentioned in Step 1 to find a topic that is uniquely your own.

• Your project should be original and focus on discovering something new or improving on something known. One way to ensure that your science investigative project is original is to have a very specific topic. For instance, let's suppose you use National Geographic and see a fascinating article about worms. You've always been interested in the creepy crawlies so you want to find out whether worms are disturbed by vibration and how people use this to catch giant earthworms from the ground.

Step 3: Research 

•        Researching your science investigative project topic is the third step.
•       After you have chosen a topic, you must become a detective seeking to uncover all the information you can about your topic.
•       Researching your science investigative project involves finding out everything you can about the scientific principles involved with it.
•       Use reliable and available resources for researching your science project. (This does not include wikepedia)
•      Tip: The most helpful thing that you can do when researching your project is to take excellent notes for your research project

Step 3a: Research - Note Taking Tips 

• Notes are an essential part of doing a science fair project.
• To keep track of your research, bring a notebook or Mac with you when you visit your local library. Record references for the books and other materials you have used in your research.
• Keep complete and accurate notes about the books and articles you find, such as:

* Author(s)
* Title
* Source for journals: Journal Title, volume, issue, date and pages of the article
* Source for books: Publisher, place of publication, date and number of pages in the book
* Title of a conference/symposium, the place and date(s)

• Take notes on simple experiments on which to base your experiment.
• Keep notes on diagrams used in similar experiments.
• Record observations from other experiments.
• Keep notes on samples of logs and other means for collecting data.
• Make lists of materials that you might need to source for your trial experiment.
• You have decided on your topic of interest, and have stated your aim of your investigation. You have researched on the scientific principles of your investigation.
• You must now form a hypothesis about your investigation, so that you can work to support it and prove that it is correct, or refute it and prove that it is wrong.

Step 4: Designing Science Experiments 

The experiment you design must effectively test your hypothesis.

When designing your experiment you want to make sure you follow the scientific method. The scientific method involves the following steps:

1.     Observation - observe something that interests you                           

2.     Question - formulate a question about what you have observed

The first two steps you have already done by making observations and coming up with a topic and specific question for your science project. (Recall step 1 & 2)

The topic and question tell what it is that you are trying to discover or accomplish in your project. Once you have your question, you must decide how you can best answer it.

Will you need to do an experiment or fieldwork? 

• 3.     Hypothesis - prediction or educated guess on what you expect will happen.If you need to observe things as they are in nature, you will need to do fieldwork.
• If you need to observe things in a controlled environment, you will need to design an experiment. When preparing to do research, a scientist must form a hypothesis, which is an educated guess about a particular problem or idea, and then work to support it and prove that it is correct, or refute it and prove that it is wrong. Whether the scientist is right or wrong is not as important as whether he or she sets up an experiment that can be repeated by other scientists, who expect to reach the same conclusion. 

The value of variables

Experiments must have the ability to be duplicated because the "answers" the scientist comes up with (whether it supports or refutes the original hypothesis) cannot become part of the knowledge base unless other scientists can perform the exact same experiment(s) and achieve the same result; otherwise, the experiment is useless.

"Why is it useless," you ask? Well, there are things called variables. Variables vary: They change, they differ, and they are not the same.

A well-designed experiment needs to have an independent variable and a dependent variable.

• The independent variable is what the scientist manipulates in the experiment.

• The dependent variable changes based on how the independent variable is manipulated. Therefore, the dependent variable provides the data for the experiment.

• Specify the materials needed
• Specify quantity
• Assumptions
• Limitations
• Conclusion

A scientific model is...

• A representation, a prototype of replica of the object/phenomenom that could well explains the physical properties
• It can be represented using animations or static diagrams
• Phenomenon includes physical phenomenom like diffusion, dissolving, boiling, condensation, evaporation, melting, sublimation etc.
• Physical properties includes volume, density, conductivity.

What are some assumations & limitations?

Assumptions

• Assumptions are valid statements to set the parameters for the models to work. Without the assumptions, the principles of the model becomes invalid or irrelevant
• Limitations are features of the model not aligned with the actual properties and not able to illustrate the principles of phenomenon
• Particles are in constant motions and in random directions.
• Particles possess kinetic energy.
• Forces of attraction exist between particles.
• Heavier particles travel slower than lighter particles.
• Particles fo not stick to each other with collision.
• Particles do not stick with the walls of container and bounces back after collision with the walls of the container.
• Particles travel in a straight line.
• Particles are small and discrete.

Limitations

• Forces of attraction between particles are not seen in the model
• Movement of particles in terms of direction and speed may not be accurately captured on static pictire but can be shown clearly on animation
• Distance between particles in model may not be scaled accurately to the actual dstance between particles

During a rock concert:

• Features similar to kinetic particle model

1. During concert, people are closely packed and jumping at fixed positions, just like particles in solid
2. When concert ends, people are moving disorderly sliding past each other but still closly packed, just like in liquid state.

• Assumpations

1. People are large in numbers yet small in size relative to entire concert hall
2. People do not stick to each other upon collision
3. Each person possess kinetic energy
4. Each person moves in a constant and random movement

• Limitations

1. People are of different sizes/ masses unlike particles whidh are of same size and mass of same substance
2. People are not standing in ordered arrangement unlike particles

States (Physical Properties)

Physical Properties

Volume

• Solid: Definite
• Liquid: Definite
• Gas: Indefinite

Shape

• Solid: Definite
• Liquid: Indefinite
• Gas: Indefinite

Density

• Solid: High
• Liquid: Middle
• Gas: Low

Compressibility

• Solid: No
• Liquid: No
• Gas: Yes

Arrangement & motion of particles to explain the physical state:

Solid - The particles of a sold are close together and in a regular pattern. The particles move very little. In solids, the particles are held together by a strong force of attraction.

Liquid - The particles of a liquid are a bit further apart than in a solid and in a less regular pattern. The particles move past each other and keep changing positions as they have more energy than solid partivles thus able to move by rolling and gliding throughout the liquid.

Gas - The particles of a gas is far apart. They have no pattern. The particles can move whenever they can. The particles of a gas are almost free of attraction from each other as they have sufficient energy to overcome forces of attraction completely. 

Kinetic Particle Theory

Physical Change

1. No new substance formed
2. Usually easily reversible
3. May/may not involve heating

Chemical Change

1. New chemical is/are formed
2. Usually irreversible ( only under special conditions )
3. Heat energy may be given off/absorbed
4. Light energy may be given off/absorbed

Signs of a Chemical Change

1. a change in colour
2. production of a gas
3. formation of a precipitate from mixing solutions
4. Change of temperature ( all the above must follow the formation of a new chemical substance ).

Process when new chemical substances are formed

1. reactants -> products 

• New chemical substances formed due to rearrangement of atoms
• No atoms are created/destroyed, according to the Law of Constant Mass

Types of Chemical Reactions

Combination (Synthesis)

• two or more substances combined to form a new substance
• magnesium + oxygen -> magnesium oxide

Decomposition

• substance breaks down 2 or more simpler substances
• calcium carbonate -> calcium oxide + carbon dioxide

Combustion / Burning

• combination of a substance with oxgen
• heat and light energy are given off
• hydrocarbon + oxygen -> carbon dioxide + water

Displacement Reaction

• a chemical reaction with an atom/a group of atoms get replaced by another atom/group of atoms
• hydrogen bromide + chlorine -> hyydrogen chloride + bromine

Definition:
States that all matter is made up of tiny particles and that these particles are in constant random motion.

Assumptions:

• All matter is made up of tiny particles.
• The tiny particles are in constant random motion.
• These particles in motion have kinectic energy.
• Higher the temperature, the faster the movement of these particles.

Melting

• Solid particles gain energy when heated
• particles vibrate faster
• as temperature increases, vibrations also increase
• finally, particles are able to overcome the forces that hold them in their fixed positions

Separation Techniques

A pure substance is made up of only one substance and is not mixed with any other substance.

We can determine the purity of a substance by:
1. checking its melting and boiling point;
2. using chromatography.

Pure substance :
- has an exact and constant/fixed melting point (melt completely at one temperature)
Effect of impurities on melting point
1) lower the melting point (the greater the amount of impurities, the lower the melting of the substance
2) melting takes places over a range of temperature- has an exact and constant/fixed boiling point
Effect of impurities on boiling point
1) boiling point will increase (greater the amount of impurities, the higher the boiling point of liquid)
2) boil over a range of temperature
Effect of pressure on boiling point
1) pressure increase, boiling point increase
2) vice versa

To test the purification of a substance, we can use chromatography.
The technique of using a solvent to separate a mixture into its components is called chromatography.
Uses of chromatography

• Separate the components in a sample
• identify the number of components in a sample
• identify the components present in a sample
• determine whether a sample is pure.

Separating solid from a liquid

Decanting

This is a way to separate the water from an insoluble solid (e.g. pebbles, sand...)

Filtration

Filtration is suitable for separating mixtures whose solid components behave

differently in a particular solvent – one component must be soluble and the other

insoluble in it. A liquid which contains insoluble solid particles is called a

suspension.To separate small solid particles from a liquid. (e.g. sand, clay, dust particles, precipitates...) After filtration, the solid that remains on the filter paper is called the residue. The liquid or solution that passes through the filter paper is called the filtrate.

Evaporation to dryness

To separate soluble solid particles from a liquid. (e.g. common salt, sugar)
We evaporate water from the solution. For example, when we evaporate salt solution to dryness, we recover solid salt. This can be used to recover salt from seawater.
However, many substances decompose when they are heated strongly. For example, sugar will decompose to give water and carbon.

Crystallisation

In crystallisation, water is removed by heating the solution. Heating is stopped at the stage when a hot saturated solution is formed. If the resulting solution is allowed to cool to roonm temperature, the dissolved solid will be formed as pure crystals.
A clean glass rod can be used to test whether a solution is saturated. It is dipped into the solution and removed. There will be a small amount of solution on the rod. If small crystals form on the rood as the solution cools, the solution is saturated. We say the solution is at its saturation point of crystallisation point.

Separating Funnel

Separating funnel is used to separate two liquids which are

immiscible, e.g. organic compounds like oil and water. The mixture is

poured into the funnel and the layers allowed to separate out. The less

dense liquid collects above the denser liquid. The lower and denser

layer is run off by opening the tap. The tap is closed as the last drop of

the denser layer runs out. The tap is then opened again to drain the

lighter layer into another beaker.

Fractional Distilation

Fractional distillation is a technique used to separate two liquids which

dissolve in one another. They are said to be miscible liquids as they mix completely

in any proportion to form a homogenous layer. The separation relies on the

difference in boiling points of the two liquids. The liquid with the lowest boiling pointis distilled first. The liquid with the highest boiling point is distilled last. A mixture of

ethanol (boiling point 78°C) and water (boiling point 100°C) may be separated using

fractional distillation because both liquids are miscible and have very different boiling

points.

Paper Chromatography

Chromatography is a technique engaged extensively in researches,

experiments, and investigations due to its sensitivity and ability to pick up minute

traces of impurities and drugs. The principle involved depends upon the relative

solubilities of the solutes (in the mixture) between the stationary phase (the paper or

plate) and mobile phase (the solvent).

Elements, Mixtures, Compounds

Facts:

1. Chemical Combined - Sodium + Chlorine = Sodium Chloride
2. Elements: Metals & Non - Metals (pg 61 TB)
3. Ion - an atom or molecule which has gained or lost one or more of its electrons, giving it a net positive or negative charge.  
4. Atom - defining structure of anelement, which cannot be broken by any chemical means. A typical atom consists of a nucleus of protons & neutrons with electrons orbiting this nucleus. 
5. Definitions of :
   Molecule - a molecule refers to 2 or more atoms which have chemically combined to form a single species.

1. Monoaomic - Helium, Argon, Krpton
2. Diatomic - O2 , H2
3. Triatomic - O3
4. Polyatomic - S8

Questions:

1. Is rusting of iron a chemical change?

Response:

1. Paper + Fire = Ash
2. Iron + Oxygen = Rust