CHEM 1411 Concept Reviews: Matter, Measurement, & Problem Solving Part I

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Matter:  Anything that has mass and takes up space. Matter can be in the form of a pure substance or a mixture.

Pure Substance:  Matter composed of only one type of molecule or one type of atom.  (Elements or compounds)

Element:  A pure substance composed of only one type of atom (i.e.-only oxygen or only iron)

Compound:  A pure substance composed of only one type of molecule (i.e.-only H₂O molecules or only CO₂)

Mixture:  Matter composed of two or more pure substances that are physically mixed but NOT chemically combined.  (Examples:  a tossed salad, cookie batter, or even a computer is a mixture of components.)

Homogenous Mixture:  A mixture that is so completely and evenly mixed that there is no difference between one part of the mixture and another part.  (Example: Maple syrup, salt water, air, and even metal alloys)

Heterogeneous Mixture:  A mixture that is not evenly mixed and where the different components can be distinguished.  (Example: Pulpy orange juice, chunky spaghetti sauce, this piece of paper which has an ink part and a paper part, etc.)

 

Physical Properties:  Characteristics that can be observed or measured without changing what the substance is.

Physical Change:  A change in state or appearance that does not affect the composition or change what it is.

Chemical Property:  the ability of a substance to react with other things or itself and become a different substance.

Chemical Change: a change where one substance reacts and becomes one or more different substances, each with different chemical and physical properties.

 

States of Matter Comparison

 

Energy

Energy:  the ability to do work or transfer heat         Work:  the action of a force applied through a distance

Kinetic Energy:  the energy of motion              Equation:  $E_k=\frac{1}{2}mv^2$   (m is mass, v is velocity)

Thermal Energy (Heat):  the energy of the motion of particles.  This energy is actually a type of kinetic energy.

Potential Energy:  any type of energy that is in a “stored” form, which includes gravitational potential energy, electrostatic potential energy, chemical potential energy, and more.

Chemical Potential Energy:  the energy stored in the structure of atoms and molecules.

Law of Conservation of Energy:  Energy is neither created nor destroyed, but only converted from one form to another.

 

Energy Conversion Diagram

1. Nuclear Fusion that occurs in the stars, including the sun, converts mass into massive amounts of electromagnetic energy that travels forth at the speed of light..
2. Light energy is absorbed and used by plants to form important biomolecules from the matter within and around them. Many of these molecules (like sugar) contain a large amount of chemical energy which can be released later through metabolic processes.  Decay of these organic materials produces various fossil fuels.
3. Metabolization of chemical energy in animals and even some plants provides the energy for movement.
4. Chemical energy in batteries and wet cells can generate electricity. Conversely, electrical energy can be used to reverse the chemical reactions in batteries or “recharge” them so that they may be used again.
5. Electricity can be used to power motors or generate sound or other mechanical waves. Conversely, turbines attached to magnets in generators can be used to produce electricity.
6. Friction and air resistance eventually convert mechanical or kinetic energy to heat.
7. Resistance in circuits causes some electrical energy (electricity) to be lost as heat.
8. Heat energy can be recycled by using it to change liquids into gasses, creating a pressure that can turn turbines and move objects.
9. Heat energy can be absorbed by chemical reactions and converted into chemical energy. Chemical energy can be converted into heat energy through chemical reactions.
10. Photoelectric cells can absorb light and convert it to electricity. Electricity can power various kinds of light bulbs, light producing gas discharge tubes, and lasers.
11. Light can be absorbed by objects and turned into heat. Conversely, an object that is heated sufficiently will start to glow and emit light.
12. Theoretically, some scientists have proposed that energy may be condensed into matter.
13. Certain chemical reactions can cause light to be emitted. There are also cases of bioluminescent creatures.