Ch 3: Scientific Measurement Flashcards
Why is it important to be able to make measurements and decide whether a measurement is correct?
Measurements are fundamental to experimental sciences.
How are all measurements made?
By comparing what you want to know with some type of standard (measuring tool).
Measurements are not usually _____. Since they are ________, they have some ___________.
exact
estimates
uncertainty
The estimate is only as good as the _________ ____.
measuring tool
Uncertainty is communicated to imply how carefully we know the measurement. The uncertainty is in the ____ _____.
last digit
Uncertainty is stated more explicitly by using ____/_____ ________.
plus/minus notation
Scientific notation is used to _____ ____ _______ and _____ _______.
write large numbers
and
small numbers
The powers of ten in scientific notation represent the _____ _____ or _________ (order of _________).
place value
or
magnitude
order of magnitude
Scientific notation: if the power of 10 is positive, you ________ by that number of 10s.
multiply
Scientific notation: if the power of 10 is negative, you ______ by that number of 10s.
divide
To evaluate accuracy of a measurement, the measured value must be compared to the _______ _____.
correct value
To evaluate precision of a measurement, the values of two or more ________ ____________ must be compared.
repeated measurements
What is the equation for error?
Error = experimental value - accepted value
What is the equation for percent error?
Percent error = |error| / accepted value X 100%
Why must measurements always be reported to the correct number of significant figures?
Calculated answers often depend on the number of significant figures in the values used in calculation.
Rules for determining significant digits: digits from - are always significant.
1-9
Rules for determining significant digits: zeros _______ ___ other significant digits are always significant (________ zeros)
between two
sandwich
Rules for determining significant digits: ___ or more additional zeros to the right of both the decimal place and another significant digit ___ significant.
one
are
Rules for determining significant digits: zeros solely used for _______ ___ _______ _____ (placeholders) are not significant.
spacing the decimal point
Rules for determining significant digits: _____ numbers or definitions of _____ have _________ or ________ number of significant figures.
exact
units
unlimited or infinite
A calculated answer cannot be more precise than the _____ precise ___________ from which it was calculated.
least
measurement
Rounding sig figs: _____ the number of significant figures in each ____ _____. Round the final answer to the _____ number of significant figures.
count
data point
least
Addition and subtraction of sig figs: the answer to an addition or subtraction problem should be rounded to the ____ number of decimal places (not ______) as the measurement with the _____ number of decimal places.
same
digits
least
Multiplication and division of sig figs: _____ the answer to the same number of significant figures as the measurement with the _____ number of significant figures.
round
least
The five SI base units are the _____, the ________, the ______, the ______, and the ____.
meter kilogram Kelvin second mole
Common metric units of length are…
centimeter
meter
kilometer
Common metric units of volume include…
liter
milliliter
cubic centimeters
microliter
What two equivalents units of temperature do scientists commonly use?
The degree Celsius and the Kelvin.
What is the equation to go from Celsius to Kelvin?
K = °C + 273
What is the equation to go from Kelvin to Celsius?
°C = K - 273
What are common units of energy?
Joule and calorie
When a measurement is multiplied by a conversion factor, the _________ value is generally changed, but the ______ ____ of the quantity measure remains the same.
numerical
actual size
What provides you with an alternative approach to problem-solving?
Dimensional analysis
What is the formula for density?
Density = mass / volume
If density doesn’t depend on the size of an object, what does it depend on?
The composition of a substance.
The heavier a substance, the ______ the density.
higher
The density of pure water is _ g/mL at its most dense (_°C).
1 g/mL
4 °C
Substances with densities lower than 1 g/mL will _____ in water.
float
Substances with densities higher than 1 g/mL will ____ in water.
sink
Mixtures of water and dissolved solids are ____ dense than water alone.
more
The density of a substance generally _________ as its temperature increases.
decreases
