Chemistry- chapter 3 test
Significant digits only apply to....
Measured data
Nano
billionth (10^-9)
Centi
hundredth 10^-2
Which of these has the greatest number of significant digits: 45620 cars, 3.35 m, or 35000 mL
45620 cars (4 significant digits)
What is the difference between accuracy and precision
Accuracy refers to the closeness of a measured value to a standard or known value. Precision refers to the closeness of two or more measurements to each other. Ex. Right on the bullseye- accuracy All darts are on/around the same spot
What is a significant digit? Why is it used?
All the certain digits plus one estimated digit They determine all the important digits you need to record in the measurement and they indicate precision of the measurement
Units of measurement that come from basic SI units units are called...
Base units
Be able to find volume, density and mass
D= M/V
A perfect measurement can be obtained
False
The unit of volume is derived from the SI unit for length (the meter)
False
When solving problems that involve compound calculations, it is best to round off at each of the intermediate steps
False
Any artificial device made for the purpose of refining, extending, or substituting for the human senses when measuring is called a(n)
Instrument
Describe what is meant by "bridge notation" and explain its value
It is used to multiple and divide several measurements at the same time and is primarily used for converting units.
Be able to convert between the metric systems
KHDUDCM (king, henry, died, unexpectedly, drinking, chocolate, milk
Be able to figure out significant digits, know the rules?
Knowing how to round up an answer 4203.00_ how many significant digits are there? There are 4 significant digits 300.02_ how many significant digits are there? There are 5 significant digits 300_ how many significant digits are there? There is one significant digit 300.0_ how many significant digits are there? There are 3 significant digits
Give four of the seven base units of the SI and the basic dimension that each represents.
Length- meter, time-seconds, mass- kilogram, temperature- kelvin
Be able to calculate density, mass, and volume
Mass/ Density * volume Mass= grams (g) , density= grams/milliliter (g/ml), volume=milliliter (ml) Ex. A block of aluminum occupies a volume of a 15.0 mL and a mass of 40.5 g. What is density? 40.5/15.0= 2.7/ml
the result of comparing an unknown quantity to a standard unit is called a/an
Measurement
What is a mole in chemistry
Number of particles in a substance
Which of these would yield a measurement with the greatest precision? (Oven thermometer, oral medical thermometer, pool thermometer, or outdoor Esther thermometer) why?
Oral medical thermometer, because it's made to be more precise
Be able to calculate percent error
Percentage error = measured value - true value/ True value
When is it important to express numbers with the proper number of significant digits?
So we can be precise and accurate
What are the common steps in problem solving? What is the first step in problem solving?
Step 1- read the statement of the problem Step 2- determine the method of solution Step 3-choose the specific tool to use Step 4- set up the problem, estimate, and calculate Step 5- check and format The first step is read the statement of the problem
You measure products of a chemical reaction to be 4.15g, 4.16g, and 4.13g. The actual mass is 4.14. How would you describe the accuracy and precision of these measurements?
The products are accurate because they are close to the actual mass but they aren't precise because they are all really close to eachother
You measure the products of a chemical reaction to be 4.52g, 3.29g, and 2.29g. The actual mass is 3.65g, how would you describe the accuracy and precision of these measurements?
They aren't accurate or precise because all the measurements are far off from the actual mass.
Measurements can be used to fulfill God's commands
True
The number 0.000640 mL should be expressed as 6.4*10-4 ml in scientific notation to eliminate ambiguity in its precision
True
A measurement is made of two essential parts. What are the two parts?
a number and a unit of measure
What is conversion factor?
a ratio of equivalent values having different units
What is the metric system?
a system of measurement based on the number 10
What does graduated mean in measurement
accurately subdivided into measurement units
What's the difference between analog and digital?
analog signals have continuous electrical signals, while digital signals have non-continuous electrical signals.
Mega
million (10^6)
Micro
millionth (10^-6)
Deci
tenth 10^-1
Kilo
thousand (10^3)
Milli
thousandth (10^-3)
