Chapter 2

Question 1

Observation

Answer 1

is the use of the senses to obtain information by taking measurement and collecting data.

Question 2

Qualitative

Answer 2

data that is descriptive

Question 3

Quantitative

Answer 3

data that is numerical

Question 4

Hypothesis

Answer 4

when scientists use generalizations about the data to formulate a testable statement
you make predictions
it is written as an “if-then” statement

Question 4

System

Answer 4

is a specific portion of matter in a given region of space that has been selected for study during an experiment/observation.
EX. when observing a reaction in a test tube, the test tube and its contents is a system

Question 5

Variable

Answer 5

any condition that changes
any change observed is due to a variable

Question 6

Constant

Answer 6

the things in the experiment that stays the same for every group.

Question 7

Control

Answer 7

the experimental support or conditions that remain constant

Question 8

Independent variable

Answer 8

what you are looking at for changes; constantly changes(x-value)

Question 9

Dependent variable

Answer 9

the outcome/result of the independent variable. (y-value) depends on the x-value

Question 10

Theory

Answer 10

a broad generalization that explains a body of facts or phenomena
usually successful in predicting
EX. gravity theory

Question 11

Model

Answer 11

In science, it is more than a physical object but an explanation of how phenomena occur and how data is related
Can be used verbally, visually, or mathematically
EX. atomic model of matter

Question 12

Derived units

Answer 12

a measurement calculated by using 2 or more simple measurements
EX. volume, area, density, and speed

Question 13

Accuracy

Answer 13

how close your measurements are to what you should have got
use percent error to check for accuracy

Question 14

Precision

Answer 14

how close your measurements are to each other

Question 15

Percentage error

Answer 15

the percentage in what you were of in an experiment using the actual value and experimental value.

Human Error: reading numbers wrong or using wrong units on accident.
Instrument Error: problem with the equipment itself or causing uncertainty with exactness of measurements.

Question 16

Scientific notation

Answer 16

a way of expressing really small or really large mathematical values in a workable way
Format: M x 10n
Variable M: CAN’T go over or be equal to 10
Variable n: must be an integer
EX. 1,000 in scientific notation is 1 x 103

Question 17

Density

Answer 17

how compact or squished a substance is; mass per unit of volume
Formula: mass/volume

Question 18

Mass

Answer 18

how much something is made of: molecules, protons, etc…
Measure using a balance(grams)

Question 19

Volume

Answer 19

the space something takes up
Measure using a graduated cylinder(liters), displacement, or LxWxH(mL)

Question 20

Scientific method

Answer 20

This is a logical approach to solving problems by observing/collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data.
When you test a hypothesis and it is not supported, you go back to formulating hypotheses and reject or remake a hypothesis.

Question 21

Experimental design

Answer 21

This involves carrying out a procedure under controlled conditions to make observations and collect data. It allows us to learn more about chemistry, matter, and more.

Question 22

Types of scientific models

Answer 22

Visual, verbal, or mathematical scientific models.

Question 23

How to use SI units (base and prefixes)

Answer 23

Use the SI units prefixes when you are taking measurements and when solving problems. Use SI unit bases with dimensional analysis to help convert them from one to another

Question 24

Base SI units

Answer 24

The SI base units are: Distance, volume, mass, weight, temperature, time, energy, and current.

Question 25

How to convert units using dimensional analysis

Answer 25

To convert units using dimensional analysis, you must use conversion factors. You have to find the base unit for example, meters. Then if it asks to convert 1 meter to 22 dekameters, you use the base units as conversion factors and solve.

Question 26

How to calculate percentage error

Answer 26

% error = (experimental value - actual value) / actual value

Question 27

What causes error and how to limit error in the lab

Answer 27

Human error is when we read numbers wrong when weighing/measuring or we use the wrong units and mess up. Then, there are instrument errors/limits where there is a specific problem with the equipment(calibration) or different tools don’t measure as specific causing uncertainty in answers. To limit error, use the digit of uncertainty where if you measure with a ruler that measures to the tenths, then you round to the hundredths.

Question 28

Why significant figures are necessary

Answer 28

They are necessary so that it makes it easier for whoever is reading your work, understands how specific your data was or was not. It also allows for easier calculations and better numbers to use and compare.

Question 29

How to count significant figures (the rules)

Answer 29

1) All nonzero digits are significant 2) Zeros at the end of a number AND to the right of the decimal point are significant 3) Zeros BETWEEN significant figures are significant 4) Zeros BEFORE all nonzero digits are NOT significant 5) Zeros at the END of a number AND to the LEFT of the decimal point MAY be significant

Question 30

How to round numbers using significant figures

Answer 30

When rounding using significant figures, it depends on what you are rounding from. it depends on the number of sig figs in both numbers and when you use it.

Question 31

How to calculate using the appropriate number of sig figs

Answer 31

In addition/subtraction, you must round to the sig fig in which the number ends first. Then, you add/subtract the numbers and add to where the sig figs end. In multiplication/division, you find the sig figs in the numbers you are multiplying or dividing. The lowest number of sig figs in one of your reactants is the number you round to when you multiply/divide.

Question 32

How to put a number into scientific notation

Answer 32

To put a number into scientific notation, you must make the number, M, less than 10 but greater than 1. However many places you move the decimal point to the left or right, that is how much you put ten to the power of. if you move the decimal left, you put ten to a positive exponent but if you move the decimal to the right, make the exponent negative.

Question 33

How to take a number out of scientific notation

Answer 33

When taking a number out of scientific notation, if the exponent is negative, you move the decimal point to the left however many times the 10 is put to the power. If the exponent is positive, you move the decimal point to the right however many times the 10 is put to the power.

Question 34

How to calculate using scientific notation

Answer 34

When using scientific notation, and you multiply two different numbers, you multiply the number, M, by each other. Then, you add the exponents of the 10*n and get your new number. Finally, depending on your multiplication of M, you might need to move the decimal left or right which then you need to increase or decrease the exponent

Question 35

How to calculate density

Answer 35

You do the amount of mass divided by the volume.

Question 36

What are the 2 things each measurement is made of?

Answer 36

Number and base

Question 37

How many of each may you have between independent and dependent variables?

Answer 37

Independent: Only one Dependent: 1 or more