Midterm Exam Flashcards
(Vocab)
Scientific Method
Organized approach to solve a problem
What are the steps of the scientific method and explain?
Observe - Define the problem (use 5 senses)
Hypothesis - Reasonable explanations for what was observed (educated guess)
Experiments - Test each hypothesis in order to prove/disapprove them
Analysis - Compares the results from the experiments to the original hypothesis
Conclusion (Theory) - A hypothesis supported by experimental evidence
(Vocab)
Law
Used to describe a natural phenomenon which has been tested over a long period of time
(Vocab)
Theory
A hypothesis supported by experimental evidence
(Vocab)
Chemistry
The study of matter + the changes it undergoes
What is the difference between an element and a compound?
Elements = made up of one atom
compounds = made up of 2 or more diff. elements (multiple atoms)
Give examples of an element.
Hydrogen, Helium, Carbon etc. (anything on the Periodic Table)
Give examples of a compound.
CO2 (carbon dioxide), NO2 (nitrogen dioxide)
(formed when elements chemically combine)
(Vocab)
Homogeneous mixture + examples
Has a uniform composition (parts of the mixture + cannot be picked out)
Ex: milk, sugar
(Vocab)
Heterogeneous mixture + examples
Doesn’t have a uniform composition (Parts of the mixture can be physically seen + picked out)
Ex: cereal, salad, pizza
(Vocab)
Chemical changes + examples
One or more substances react to form new substances w/ diff. chemical + physical properties (The beginning substances w/ diff. than the ending substances)
Ex: rusting, burning, decaying
(Vocab)
Physical changes + examples
Changes in appearance w/o changing composition
Ex: cutting, breaking, freezing, boiling, melting
(Vocab)
Physical Properties + examples
Properties that can be measured or observed w/o changing the identity (or composition) of a substance
Ex: color, odor, texture, taste
(Vocab)
Chemical Properties + examples
Properties that indicate how a substance reacts w/ other substances.
Ex: flammable, combustible, burnable
(Vocab)
Law of Conservation of Matter/Mass
In any chemical or physical change, matter cannot be created or destroyed (mass of reactants = mass of products)
Explain the difference between accuracy and precision.
Accuracy = How close a measurement is to the true or accepted value
Precision = How close multiple measurements are to each other
Write out 3.5 x 10^-5 in long form.
0.000035
Write out 7,123 in scientific notation
7.123 x 10^3
Write out 0.000000081 in scientific notation
8.1 x 10^-8
Write out 8 x 10^8 in long form.
800,000,000
Answer (6 x 10^-8) x (4x10^-4) in proper scientific notation.
2.4 x 10^-11
Write out 453,000 in scientific notation
4.53 x 10^5
Write out 0.000157 in scientific notation
1.57 x 10^-4
Solve: 30,000 x 0.0004 in scientific form
1.2 x 10^1
Write out 2 x 10^3 in long form.
2000
Solve: (3 x 10^-8) x (7 x 10^6) in scientific notation
2.1 x 10^-1
Write out 0.0029 in scientific notation.
2.9 x 10^-3
Solve: 37,000 x 7,000 in scientific notation
2.59 x 10^8
Write out 41,000 in scientific notation.
4.1 x 10^4
Write out 60,007,000 in scientific notation.
6.0007 x 10^7
List the rules for Significant Figures
1) All non-zero digits are significant
2) Leading zeros are never significant (zeros to the left)
3) Captive zeros are always significant (zeros in the middle)
4) Trailing zeros are sometimes significant (zeros at the end)
- they are sig. if the # contains a decimal point
- they aren’t sig. if # does NOT contain a decimal point
What is the rule for Addition and Subtraction when solving an equation with sig. figs.?
the answer is rounded to the same # of decimal places as the # used in the calculation with the least decimal places.
Ex #1: 7.12 - 1.345 = 5.775 = 5.78
(7.12 has the least number of decimal places in the equation so we would round our answer 5.775 to have the same amt of decimal places. This would make the answer 5.78, which is also rounded to the nearest hundredth, DONT FORGET TO ROUND)
Ex #2: 5.7 + 2.11 = 7.81 = 7.8
What is the rule for Multiplication and Division when solving an equation with sig. figs.?
the answer is rounded to the same # of sig. figs. as the # used in the calculation with the least sig. figs.
Ex #1: 17.85/2.13 = 8.38028 = 8.38
(You divide the 2 #’s and get that long number but since 2.13 is the # with the least sig. figs. you round your answer to get the same amt of sig. figs., which is 3, this will lead you to get the answer 8.38)
Ex #2: 0.0561 x 0.030 = 0.001683 = 0.0017 (rounded)
What is Dimensional Analysis?
A method used to convert units
Solve using Dimensional Analysis, How many seconds are in 1.50 weeks?
907 s
how many sig. figs. are in the number 0.02?
1
(Vocab)
Matter
Anything that has mass + volume (everything)
How many g are equal to 345.7 mg?
0.3457
How many Micrograms (μg), Microliters (μL), and Micrometers (μm) are in grams (g), liters (L), and meters (m)?
10^-6μg = 1g
10^-6μL = 1L
10^-6μm = 1m
(Vocab)
Mass
The amount of matter in an object
how many sig. figs. are in the number 0.020?
2
Solve using Dimensional Analysis, how many feet are equal to 54.7 inches?
4.56 ft
How many Kg are equal to 45,000 mg?
0.045 kg
How many Milligrams (mg), Milliliters (mL), and Millimeters (mm) are in grams (g), liters (L), and meters (m)?
1000mg = 1g
1000mL = 1L
1000mm = 1m
Answer the equation with the correct amt of sig. figs.
16.590/1.8 = ?
9.2
how many sig. figs. are in the number 2.0x10^-3?
2
How many mins are in an hour?
60 mins.
How much feet are in a mile?
5280 feet
Mount Everest is approximately 8,000 meters high. How many miles high is Mount Everest?
5 miles
What is the symbol and meaning for the prefix micro?
Symbol: μ
Meaning: millionth (10 ^-6)