Download Chapter 2 Guided Notes

Chapter 2 Guided Notes: Matter & Energy
Section 1: Energy
Objectives
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Explain that physical and chemical changes in matter involve transfers of energy.
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Apply the law of conservation of energy to analyze changes in matter.
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Distinguish between heat and temperature.
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Convert between the Celsius and Kelvin temperature scales.
____________ is the capacity to do some kind of work, such as moving an object, forming a new
compound, or generating light. Energy is always involved when there is a change in matter. A physical
change is a change of matter that affects only the ____________ properties of the matter. A chemical
change is a change that occurs when one or more substances change into entirely new ____________
with different properties. Any change in matter in which energy is absorbed from the surroundings is an
_______________ process. The melting of ice and the boiling of water are examples of physical changes
that are endothermic. Any change in matter in which energy is released is an ____________ process.
The freezing of water and the condensation of water vapor are two examples of physical changes that
are exothermic processes. The law of conservation of _________ states that during any physical or
chemical change, the total quantity of energy remains constant. In other words, energy cannot be
destroyed or created. To keep track of energy changes, chemists use the terms system and
surroundings. A ___________ consists of all the components that are being studied at any given time.
The _______________ include everything outside the system.
Energy exists in different forms, including
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chemical
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heat
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mechanical
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electrical
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light
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sound
The transfer of energy between a system and its surroundings can involve any one of these
forms of energy. __________ is the energy transferred between objects that are at different
temperatures. Heat energy is always transferred from a warmer object to a cooler object. Kinetic energy
is the energy of an object that is due to the object’s ____________. Temperature indicates how hot or
cold something is. Scientists define _____________________ as a measurement of the average kinetic
energy of the random motion of particles in a substance. The zero point on the Kelvin scale is designated
as _____________ _________, the temperature at which the minimum average kinetic energies of all
particles occur. The ____________ heat of a substance is the quantity of energy as heat that must be
transferred to raise the temperature of 1 g of a substance 1 K.
Section 1 Review Questions:
1. What is energy?
2. Differentiate between temperature and heat.
3. Convert the following:
a. 1000C to Kelvin
b. 273 K to Celsius
c. 350C to Kelvin
d. 35 K to Celsius
4. Is breaking an egg an example of a chemical or physical change? Justify.
Chapter 2, Section 1 Concept Map
Using the vocabulary words from the section, make a concept map to connect them. Each vocabulary
word must be connected to another using a word or phrase to make a sentence that makes sense.
Vocabulary Words:
Energy
System
Electrical
Physical Change
Surroundings
Sound
Chemical Change
Chemical
Kinetic energy
Law of Conservation of
Energy
Mechanical
Potential energy
Light
Temperature
Heat
Specific heat
Endothermic
Exothermic
Section 2: Studying Matter & Energy
Objectives:
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Describe how chemists use the scientific method.
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Explain the purpose of controlling the conditions of an experiment.
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Explain the difference between a hypothesis, a theory, and a law.
The _________________ method is a series of steps followed to solve problems, including
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collecting data
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formulating a hypothesis
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testing the hypothesis
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stating conclusions
An ___________ is the process by which scientific ideas are tested. A ___________ is a
reasonable and testable explanation for observations. A factor that could affect the results of an
experiment is called a ____________. When a variable is kept constant from one experiment to the
next, the variable is called a ___________. The procedure is called a controlled experiment. In science, a
__________ is a well-tested explanation of observations. Theories are explanations, not facts, so they
can be disproved but can never be completely proven. A _________ is a statement or mathematical
expression that reliably describes a behavior of the natural world. For example, the law of conservation
of mass states that the products of a chemical reaction have the same mass as the reactants. A _______
represents an object, a system, a process, or an idea.
Section 2 Review Questions:
1. How does a hypothesis differ from a theory?
2. Suppose you had to test how well two types of soap work. Describe your experiment in term
of the control and variables.
3. What is an example of a model that is used in chemistry class.
Section 3: Measurements and Calculations in Chemistry
Objectives:
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Distinguish between accuracy and precision in measurements.
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Determine the number of significant figures in a measurement, and apply rules for significant
figures in calculations.
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Calculate changes in energy using the equation for specific heat, and round the results to the
correct number of significant figures.
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Write very large and very small numbers in scientific notation.
The accuracy of a measurement is how close the measurement is to the true or actual value. Precision
refers to how closely several measurements of the same quantity made in the same way can agree. The
_____________ figures of a measurement or a calculation consist of all the digits known with certainty
as well as one estimated, or uncertain, digit. The last digit or significant figure reported after a
measurement is uncertain or estimated.
Rules for Determining Significant Figures:
1. Nonzero digits are always significant.
2. Zeros between nonzero digits are significant.
3. Zeros in front of nonzero digits are not significant.
4. Zeros both at the end of a number and to the right of a decimal point are significant.
5. Zeros both at the end of a number but to the left of a decimal point may not be significant. If a
zero has not been measured or estimated, it is not significant. A decimal point placed after zeros
indicates that the zeros are significant.
Rules for Using Significant Figures in Calculations:
1. With multiplication and division, the answer cannot have more significant figures than the
measurement with the smallest number of significant figures.
2. With addition and subtraction, the result can be no more certain than the least certain number
in the calculation.
3. If a calculation has both addition (or subtraction) and multiplication (or division), round after
each operation.
Section 3 Review Questions:
1. How does accuracy differ from precision?
2. Perform the following calculations and express your answers using the correct number of
significant figures:
a. 0.8102 m X 3.44 m
b. 32.89 g + 14.21 g
c. 94.20 g / 3.16722 mL
d. 34.09 L – 1.230 L
3. Express the following numbers in scientific notation:
a. 1,000,000 m
b. 30,000 m/s
c. 0.000 000 000 32 g
d. 0.000 000 000 000 025 L