Chapter 2 Notes IChapter 2 Notes I

Quantitative/qualitativeQuantitative/qualitative

Accuracy/precisionAccuracy/precision

Standard Units &Standard Units &

Metric ConversionsMetric Conversions

Types of Types of measurementsmeasurements

QualitativeQualitative-measurements -measurements describing the qualities or describing the qualities or characteristics of somethingcharacteristics of something

QuantitativeQuantitative-measurements that -measurements that focus on actual numerical datafocus on actual numerical data

What type of data is What type of data is the following:the following:

The beaker is hot.The beaker is hot.The beaker is 37The beaker is 37ooC.C.A yellow precipitate forms.A yellow precipitate forms.Water has a density of 1.0g/ml.Water has a density of 1.0g/ml.

Accuracy vs. Accuracy vs. PrecisionPrecision

AccuracyAccuracy-how close a -how close a measurement is to the actual measurement is to the actual value.value.

PrecisionPrecision-how close a set of -how close a set of measurements are to each other.measurements are to each other.

What is an example of:What is an example of:

-something both accurate -something both accurate and precise.and precise.

-something precise but -something precise but not accurate.not accurate.

-something accurate but -something accurate but not precise.not precise.

Accuracy and PrecisionAccuracy and Precision

What are the precision and accuracy levels of the following?What are the precision and accuracy levels of the following?

Low Accuracy High Accuracy Low Accuracy High Precision High Precision Low Precision

Whose data is most accurate/precise?Whose data is most accurate/precise?

Three chemistry students measured the mass and volume of a piece of zinc Three chemistry students measured the mass and volume of a piece of zinc to determine it’s density. to determine it’s density.

The table below shows the data:The table below shows the data:

JohnJohn SamSam SaraSara

Trial 1Trial 1 7.17 g/mL7.17 g/mL 7.65 g/mL7.65 g/mL 7.04 g/mL7.04 g/mL

Trial 2Trial 2 7.14 g/mL7.14 g/mL 7.65 g/mL7.65 g/mL 7.55 g/mL7.55 g/mL

Trial 3Trial 3 7.13 g/mL7.13 g/mL 7.64 g/mL7.64 g/mL 7.26 g/mL7.26 g/mL

AverageAverage 7.15 g/mL7.15 g/mL 7.65 g/mL7.65 g/mL 7.28 g/mL7.28 g/mL

Compare the students data.

Whose data is the most accurate and precise?

What is the mass on this quadruple-beam balance?

0

0

0

0

100 200 300 400 500

10 20 30 40 50 60 70 80 90

1

0.1

2

0.2

3

0.3

4

0.4

5

0.5

6

0.6

7

0.7

8

0.8

9

0.9

What is the smallest place value on this equipment? What place value should this measurement go to? What is the measurement?

hundredths hundredths placeplace

thousandths thousandths placeplace

..

22

22

66

22

88

66

226.286 226.286 gramsgrams

What is the mass on this quadruple-beam balance?

0

0

0

0

100 200 300 400 500

10 20 30 40 50 60 70 80 90

1

0.1

2

0.2

3

0.3

4

0.4

5

0.5

6

0.6

7

0.7

8

0.8

9

0.9

What is the smallest place value on this equipment?

hundredths hundredths placeplace

What place value should this measurement go to?

thousandths thousandths placeplace

What is the measurement?

00

11

88

00

77

00

18.070 18.070 gramsgrams

.

The Metric The Metric SystemSystem

What is Metrics?What is Metrics?

Based on factors of tenBased on factors of ten

Also Called International System (SI)Also Called International System (SI)

Why use metrics in Why use metrics in science?science?

Factors of ten are much easier to Factors of ten are much easier to work with.work with.

Research does not just occur in Research does not just occur in the U.S.—a global community the U.S.—a global community requires a universal measuring requires a universal measuring system.system.

Standard UnitsStandard Units

LengthLengthMassMassTimeTimeTemperatureTemperatureAmount of substanceAmount of substance

meter

kilogramsecond

Deg. Celsius

mole

Derived UnitsDerived Units

AreaAreaVolumeVolume

DensityDensityConcentrationConcentrationEnergyEnergy

Square meter (m2)

Cubic meter (m3)

Though this is the standard, we will Though this is the standard, we will mostly use liters!mostly use liters!

Kg/m3

Moles/liter

Joules (force x length

Metric PrefixesMetric Prefixes

Each prefix signifies an amount of Each prefix signifies an amount of base units represented.base units represented.

The metric system is base 10 system that only requires the movement of the decimal point to change units. The prefixes of the metric system are:

Mega (M) =**Kilo (k) =Hecto (h) =Deka (da) =

**Unit =

(liter) (mete

r) (gram) Deci (d) =

Centi (c) =

**Milli (m) =

mightymighty

kingking

HenryHenry

drinksdrinks

ultraultra

darkdark

chocolatchocolatee

milkmilk

1 000 000 units 1 000 000 units (10(1066))1 000 units (101 000 units (1033))100 units (10100 units (1022))10 units (1010 units (1011))

1 unit (101 unit (1000))

0.1 units (100.1 units (10-1-1))

0.01 units (100.01 units (10-2-2))

0.001 units (100.001 units (10-3-3))

**Notice…everything **Notice…everything revolves around the unit!!!revolves around the unit!!!

**width of a **width of a dimedime

**about the **about the distance across distance across TexasTexas

Metric PrefixesMetric Prefixes

To convert b/n units, start at the given and ‘jump’ to the unknown. If you jump up, move the decimal that many places to the left. If you jump down, move the decimal that many places to the right. Mega

kilo hecto deka unit deci

centi milli

Practice:

32.4 g = _________ kg

65298 mL = _________ daL

628.7 m = _________ dm

jumped jumped upup 3 times = decimal to 3 times = decimal to the left 3 timesthe left 3 times

..00

0.0320.03244 jumped jumped upup 4 times = decimal to 4 times = decimal to

the left 4 timesthe left 4 times 6.5296.52988

.. jumped jumped downdown once = decimal once = decimal

to the right onceto the right once ..

6,2876,287