Exam #2

Question 1

What types of errors cause uncertainty in measurements?

Answer 1

1. instrument error
2. human error
3. method error

Question 2

example of an instrument error

Answer 2

not calibrated, broken, missing an increment

Question 3

example of human error

Answer 3

reading a measurement incorrectly/not reporting data to the correct uncertain digit

Question 4

example of method error

Answer 4

not reading meniscus properly, not using standard method

Question 5

what is the difference between accuracy and precision?

Answer 5

accuracy is how reliable the measurements are and precision is how finely the measurements are made

Question 6

what are significant figures?

Answer 6

all the certain numbers plus one uncertain digit

Question 7

what is the purpose of significant figures?

Answer 7

they help to determine the uncertainty of a measuring instrument which allows you to determine the precision of the instrument

Question 8

how do you determine precision of a lab instrument?

Answer 8

the lower the amount of uncertainty the greater the relative precision

Question 9

what does the SI system stand for?

Answer 9

international system of units

Question 10

who uses the SI system and why?

Answer 10

the scientific community, provides a standard comparison for measurement when conducting research/ allows the community to share research without needing conversions and errors

Question 11

what 2 advantages does the SI system have when doing calculations?

Answer 11

1. it is based on the power of 10 so conversions are easier (moving decimal place)
2. measurements are in decimal form so calculations are easier

Question 12

What are the 4 fundamental SI base units and their symbols for mass, length, time and temperature?

Answer 12

mass- kilogram (kg)
length- meter (m)
time- seconds (s)
temp.- Kelvin (K)

Question 13

what is the difference between heat and temperature?

Answer 13

temp. -measures the kinetic energy of a sample and does not rely on the samples mass
heat- refers to the total amount of energy in a sample available to transfer from an object with a higher temp to an object with a lower temp., (KE and PE), depends on the mass of the sample

Question 14

what instrument is used to measure temp.?

Answer 14

thermometer, lab unit is celsius

Question 15

what instrument is used to measure heat?

Answer 15

a calorimeter, SI unit- joules , non-SI- calories

Question 16

what does density depend on?

Answer 16

temp. and pressure (gases only)

Question 17

why is water the exception of density?

Answer 17

particles in the solid phase of water are in a fixed position so positives arent next to positives and negatives arent next to negatives, H2O molecules are spread farther apart in the solid state than the liquid state, water expands as it freezes

Question 18

why is density usually D(s)-D(l)-D(g)?

Answer 18

as heat energy is input into a phase to change it, the particles increase in kinetic energy which increases the temp. up until the melting/boiling point where the particles will increase in potential energy and increase the distance between them. Dependent on how close the particles are packed together in a certain volume