topic: temperature & percent error & density again do now: look at test objectives
TRANSCRIPT
Topic: Temperature & Percent Error & Density again
Do Now: Look at test objectives
Temperature
Scientifically speaking …
The definition of temperature:
Temperature is measure of average kinetic energy of particles in system
Absolute Zero
• Zero on the Kelvin scale: point at which all matter is said to stop moving
World’s Record Cold Temperatures
Date ˚F ˚C
World (Antarctica) Vostok II 7/21/1983 –129 –89Verkhoyansk, Russia (Siberia) 2/7/1892 –94 –70Asia Oimekon, Russia 2/6/1933 –90 –68Greenland Northice 1/9/1954 –87 –66N.A. Snag, Yukon, Canada 2/3/1947 –81 –63U.S. Prospect Creek, Alaska 1/23/1971 –80 –62U.S. (other than AK) Rogers Pass, Mont. 1/20/1954 –70 –56.5
Conversion formulas
How can we convert from one temperature scale to another?
K = °C + 273 (more precisely 273.15)
°C = K – 273
[F = (9/5 °C) + 32]
Percent Error
measured value – accepted value x100% accepted value
use absolute value – use absolute value – answer always positiveanswer always positive
Data tableData table
1.711.451.57Trial 3
1.691.681.60Trial 2
1.701.401.54Trial 1
Student C
(g/cm3)
Student B
(g/cm3)
Student A
(g/cm3)
Students were asked to find the density of sucrose [Sucrose has a density of 1.59 g/cm3]
Advantage of % Error
•Makes it easier to compare data, especially if comparing data from different trials
Density Review
M
D V
Looking at this graph again, what is the density of pyrite? HINT: SLOPE
What is this graph missing?
Scientific Notation
• The number is written as the productproduct of two other numbers:
– A number between 1 and 10 (notnot 10)
– and
– A power of 10
Converting conventional conventional toto scientific notationscientific notation
For numbers 1 1, the exponentexponent will be positivepositive. Count how many places the decimal is moved.
329 3.29 X 102
Converting conventional conventional toto scientific notationscientific notation
For numbers between 0 and 1between 0 and 1, the exponentexponent will be negativenegative. Count how many places the decimal is moved.
0.00045 4.5 X 10-4
Converting scientific to scientific to conventionalconventional notation
If the exponent is positive, the number 1, so move the decimal point right.
3.784 X 105 378400
Converting scientific to scientific to conventionalconventional notation
If the exponent is negative, the number is between 0 and 1 so move the decimal point to the left.
2.75 X 10-3 0.00275