Chapter 1 Flashcards
(112 cards)
1
Q
summarize the steps of the scientific method
A
- carefully define the problem
- perform experiments
- make observations
- record information or data about the system (data will either be qualitative or quantitative)
- interpretation
- hypothesis
- more experiments are made to test the hypothesis, and the process begins again
2
Q
what is the scientific method?
A
the scientific method is a systematic approach to research
3
Q
what is the difference between qualitative and quantitative data?
A
-Qualitative data consists of general observations about the system. (describes the observation).
-Quantitative data comprises numbers obtained by various measurements of the system. (how much?).
4
Q
scientific knowledge is empirical. what does this mean?
A
Empirical means that is is based on observation and experiment. (scientists observe and perform experiments on the physical world to learn about it)
5
Q
chemistry is the science that seeks to understand _____
A
chemistry is the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules.
6
Q
chemistry observes ____
A
chemistry observes the changes that matter undergoes and measures the amount of energy produced or consumed during those changes
7
Q
the scientific approach to knowledge consists of what three things?
A
Laws, theories, and observations
8
Q
what is a law?
A
A law is a concise verbal or mathematical statement of a relationship between phenomena that is always under the same conditions. Laws are proven to be correct, they always stay the same and are constants.
9
Q
what is a theory?
A
A theory is a unifying principle that explains a body of facts and/or those laws that are based on them. Theories aren’t proven correct and aren’t constant. The part of theories that change is the “why”.
10
Q
what two things can an observation lead to?
A
observation either leads to a law or hypothesis. both the law and hypothesis have to be tested. the hypothesis can lead to a theory, which also gets tested.
11
Q
all things that are physically real (air we breathe, sunshine, the ground) are forms of either _____ or _____
A
all things that are physically real (air we breathe, sunshine, the ground) are forms of either matter or energy.
12
Q
what is matter?
A
Matter is anything that has mass and occupies space.
13
Q
A specific instance of matter is called a _____
A
A specific instance of matter is called a substance
14
Q
what two things are matter classified by?
A
Matter is classified by its state (whether its solid, liquid, or gas) and composition (the kinds and amounts of substances that compose it)
15
Q
define mass
A
mass is the property that defines the quantities of matter in an object
16
Q
define a substance
A
a substance is a form of matter that has a definite (constant) composition and distinct properties
17
Q
what can substances be identified by?
A
substances can be identified by its appearance, smell, taste, and other properties.
18
Q
what is energy?
A
energy is the capacity to transfer heat or do work. we want chemical reactions to transfer heat or do work.
19
Q
what are two types of matter?
A
- Mixture
- Pure substance
20
Q
what is a mixture?
A
a mixture is a substance composed of two or more substances in which the substances retain their distinct identities that can be combined in continuously variable proportions
21
Q
what states of matter can mixtures be in?
A
solid, liquid, or gas
22
Q
do samples of mixtures have the same physical and chemical characteristics?
A
samples of the substance of the mixture may not have the same physical and chemical characteristics.
23
Q
mixtures can either be _____ or ______
A
mixtures can either be heterogenous or homogenous
24
Q
what is a heterogenous mixture?
A
- A heterogeneous mixture is a substance whose composition is NOT uniform.
- substances AREN’T mixed uniformly.
- regions within the sample can have DIFFERENT chemical and physical characteristics
25
what is a homogenous mixture?
- a homogenous mixture is a substance in which the composition of the mixture is the SAME throughout.
- substances ARE mixed uniformly.
- regions within the sample can have the SAME chemical and physical characteristics - no matter where you test, it will all have the same chemical and physical characteristics.
26
what is the second type of matter - a pure substance?
a pure substance is a substance composed of only a single type of atom or molecule
27
what states of matter can a pure substance be in?
solid, liquid, or gas
28
do samples of pure substances have the same physical and chemical characteristics?
yes, all samples of a pure substance have the same physical and chemical characteristics
29
what are the two types of pure substances?
the two types of pure substances are element and compound
30
what is an element?
an element is a substance that cannot be separated further into simpler substances by chemical methods
31
what are the characteristics of elements?
-they are the basic building blocks of matter
-they are composed of a single type of atom
-they are rare in nature
-can be solid, liquid, or gas
32
what is a compound?
a compound is a substance composed of atoms of two or more elements chemically united in fixed proportions
33
what are the characteristics of a compound?
-they are the most common pure substance.
- they can be solid, liquid, or gas
- most things we interact with are compounds
34
can compounds be broken down into elements? how?
yes, compounds can be broken down into elements by chemical reaction (not just a magnet)
35
what are the three states of matter?
solid, liquid, and gas
36
in solid matter, how are the atoms and molecules packed?
in solid matter, atoms or molecules are packed closely to each other in fixed locations.
37
can the atoms or molecules in solid matter vibrate? can they move around or past each other?
Yes, the atoms and molecules in solid matter CAN vibrate, but they DO NOT move around or past each other
38
on an atomic level of solid matter, can the molecules get any closer, and is there volume between each molecule?
on an atomic level of solid matter, the molecules CANNOT get any closer, and there is NO volume between each molecule
39
What are the volume and shape of a solid?
solid matter has a FIXED volume and RIGID shape
40
are solids compressible?
no, solids are incompressible
41
what are the two different types of solids?
1. Crystalline solid: regularly ordered structure with repeating pattern.
2. Amorphous solid: no long-range order with no repatting pattern.
42
in liquid matter, how are the atoms/molecules packed, and can they move?
in liquid matter, atoms or molecules are packed closely to each other, BUT are free to move relative to each other
43
what are the volume and shape of a liquid?
liquid matter has a FIXED volume but NOT a fixed shape - it assumes the shape of the container
44
is liquid matter compressible?
liquid matter is somewhat compressible - since there is more space between liquid molecules
45
in gaseous matter, how are the atoms/molecules packed, and are they able to move?
In gaseous matter, atoms or molecules have a lot of space between them and are free to move relative to one another
46
does gas assume the shape and volume of the container?
yes, gas assumes the shape AND volume of the container
47
is gas compressible?
gas is compressible since there is a lot of space between the atoms
48
can the three states of matter be interconverted without changing the composition of the substance?
yes, the three states of matter CAN be interconnected without changing the composition of the substance.
49
what are the 3 characteristics when differentiating the three states of matter?
shape, volume, and compressibility
50
properties of matter can either be ____ or ______
properties of matter can either be physical or chemical
51
what are physical properties?
physical properties are the properties that can be measured and observed WITHOUT changing the composition or identification of a substance.
52
what do physical properties correspond to?
physical properties correspond to physical changes in the substance. physical properties are always associated with physical changes.
53
can we manipulate physical changes? what changes?
We can manipulate physical changes but on a molecule level, nothing changes. Just appearance.
54
what is an example of a physical change?
liquid to gas.
bioling. cutting or crushing.
55
what are chemical properties?
chemical properties are properties of a substance that can be observed by changing its compositions.
56
what do chemical properties correspond to?
chemical properties correspond to chemical changes in the substance.
57
can we change chemical properties? what are the changes accompanied by?
yes, chemical changes are often evidenced by heat exchange or color changes. not ALL color changes will be chemical changes. sometimes, a physical change can include a color change in the real eye. but MOST color changes happen in chemical changes.
58
what is an example of chemical change?
iron rusting - the reactants in the chemical equation look different from the products, meaning there was a chemical reaction.
59
what can confirm whether a change is physical or chemical?
only a chemical examination can confirm whether a change is physical or chemical
60
T/F: the physical and chemical properties of a compound can be very different from those of the elements that combine to form it
TRUE
61
physical and chemical properties of matter have what two properties?
intensive properties and extensive properties
62
what are intensive properties?
intensive properties are those that are INDEPENDENT of the amount of substance present. they are internal
63
what are the characteristics of intensive properties?
-Color
-Hardness: soft
-malleability
-Melting temperature: 1064 degrees C
64
what is an example of an intensive property?
the color of gold in an intensive property will always be the same gold color
65
what are extensive properties?
extensive properties are those that vary with the quantity of the substance present. It is external
66
what are the characteristics of extensive properties?
-length
-width
-mass
-volume
67
what is an example of extensive properties?
mass, which is the quantity of matter in a given sample of a substance, is an extensive property
68
how to differentiate between intensive vs. extensive?
cut the item in half. whatever is still inside, if it is the same, then that is intensive.
69
what are the SI bases and their measurement?
-Length: Meter (m). Commonly use centimeters (cm).
-Mass: kilogram (kg). Commonly use gram (g).
-Time: seconds (s)
-Temperature: Kelvin
70
what is the difference between mass and weight? are they interchangeable?
-Mass depends on only the amount of substance (it doesn't depend on the weight of gravity).
-Weight depends on the amount of substance AND the force due to gravity on it.
-These terms are interchangeable in class, but not for scientists. Scientists use mass.
71
what is a derived unit?
a combination of other units
72
what are the derived units for volume and density?
-Volume: m^3
-Density: kg/m^3 (but most often expressed in g/cm^3 or g/mL)
73
what are other units for volume?
liter (L) and milliliter (mL)
and cm^3 which is cc, which stands for cubic centimeters in medicine.
74
the density of a substance is the ratio of its ____ to _____
the density of a substance is the ratio of the mass to its volume
75
is density an intensive or extensive property?
density is an intensive property of a substance. because density doesn't change based on how much we have. so mass and volume can change but density doesn't change. it is independent of mass and volume.
76
is density temperature dependent?
yes because volume changes with temperature. (water expands with heat and rises)
77
are there negative temperatures with Kelvin?
no and with K the denominator is never 0
78
what are prefix multipliers?
they change the value of the unit by powers of 10 (just like an exponent does in scientific notation)
79
is mega bigger or smaller than the base unit? what is its measurement?
mega is bigger.
10 to the power of 6 or 1,000,000
80
is kilo bigger or smaller than the base unit? what is its measurement?
kilo is bigger.
10 to the power of 3 or 1000
81
is deci bigger or smaller than the base unit? what is its measurement?
deci is smaller.
10 to the power of negative 1.
0.1
82
is centi bigger or smaller than the base unit? what is its measurement?
centi is smaller.
10 to the negative 2.
0.01
83
is milli bigger or smaller than the base unit? what is its measurement?
milli is smaller.
10 to the negative 3.
0.001
84
is micro bigger or smaller than the base unit? what is its measurement?
micro is smaller.
10 to the negative 6.
85
is nano bigger or smaller than the base unit? what is its measurement?
nano is smaller.
10 to the negative 9
86
is pico smaller or bigger than the base unit? what is its measurement?
pico is smaller
10 to the negative 12
87
for instruments marked with a scale, such as a balance, how do you get the last digit?
for instruments marked with a scale, such as a balance, you get the last digit by estimating between the marks (if possible)
88
if it says the markings are every 1g, then what do we know and what can we estimate?
if it says the markings are every 1g, then we know that 1 is significant and the next digit will be uncertain. You can estimate the reading as 1.2 g for example, where the second digit is uncertain.
89
what are the significant figure rules?
-a zero may or may not be significant depending on its location in a number
-zeros that locate the decimal point are NOT significant
-terminal zeros ARE significant if they indicate precision and are NOT significant if they don't indicate precision, and instead are conversion zeroes, for example.
-terminal zeros followed by a decimal point are always significant
90
what 3 examples don't apply to significant figures?
Counting
Define quantities
Integers in eqations
91
what is the rule with sig figs when adding/subtracting?
the final answer has the least amount of decimal places
92
what is the rule with sig figs with multiplying/dividing?
the final answer has the least amount of significant figures
93
what is the rounding rule if a number ends with 5?
if the number to the left of the 5 is even, round down.
if the number to the left of the 5 is odd, round up.
94
do we round in every step of an equation?
no, we only round at the very end. but keep track of your significant figures.
95
what are 3 types of error?
-Random error
-Systemic error
-Gross error
96
what is random error?
Random error occurs whenever a measurement is made. It is usually not that big of a deal
97
what is random error caused by?
-Random error is caused by the many uncontrollable variables that are an inevitable part of every physical or chemical measurement.
-There are many contributors to random error, but often we cannot positively identify or measure them because they are small enough to avoid individual detection.
98
what does random error cause?
random error causes data to be scattered more or less symmetrically around a mean value.
99
the accumulated effect of the individual random uncertainties causes what to occur in random error?
the accumulated effect of the individual random uncertainties causes the data from a set of replicate measurements to fluctuate randomly.
100
what is systemic error?
Systemic error is a bigger deal and you don't want to make this error. These have definite values, an assignable cause, and are of about the same magnitude for replicate measurements made in the same way.
101
what does systemic error lead to?
it leads to bias in measurement techniques. it affects all the data in a set in approximately the same way that it bears a sign.
102
what does systemic error cause?
it causes the mean of a set of data to differ from the accepted value
103
what are 3 ways systemic errors arise?
1. Instrumental errors - caused by imperfections in measuring devices and instabilities in their components.
2. Method errors - arise from non-ideal chemical or physical behavior of analytical systems.
3. Personal errors - results from carelessness, inattention, or personal limitations of the experimenter.
104
what is gross error?
gross error is basically human fumble
105
define accuracy
Accuracy refers to how CLOSE the measured value is to the actual value. The more accurate you are, the closer you are to the actual value.
106
define precision
Precision refers to how close a series of measurements are to one another, or how reproducible they are. The more measurements we make, the closer our value is to the correct number.
107
what is the difference between accuracy and precision?
Accuracy refers to how close a measurement is to the true or accepted value. Precision refers to how close measurements of the same item are to each other.
108
what are some examples of heterogenous mixtures?
chicken noodle soup, oil and water, and sand.
109
what are some examples of homogenous mixtures?
air, sugar water, rainwater, vinegar, dishwashing detergent, steel, cup of coffee, mouthwash.
110
what are some examples of elements?
Examples of elements include iron (Fe), hydrogen, gold, silver, and copper. Elements are made up of atoms that are all the same.
111
what are some examples of compounds?
Examples of compounds include water (H₂O), table salt (NaCl), and carbon monoxide. Compounds are made up of two or more different types of atoms that are connected by chemical bonds.
112
what is dimensional analysis?
to convert from one unit to another we use conversion factors - a fractional quantity with units you are converting FROM (initial units) on the bottom and the units you are converting TO (desired units) at the top. This is always your conceptual plan. ALWAYS write units with the quantities.
