Topic: Temperature & Percent Error & Density againDo Now: Look at test objectives

TemperatureScientifically 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 formulasHow 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