Today's Agenda- SLO pretest Lab safety ... - Honors Chemistryknightshonorschem.weebly.com/uploads/3/7/2/4/... · Measurement Honors Chemistry (2).notebook 4 August 12, 2015 Aug 9

Measurement Honors Chemistry (2).notebook

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August 12, 2015

Aug 5 2014

Mr. AkinsHonors Chemistry Aug. 3, 2015

Warm-up:Compare your expectations of chemistry with your experience in biology.

Today's Agenda-• Welcome and introductions• Syllabus• Procedures

Aug 7 2014


Warmup:What equipment are we using in the lab tomorrow?

Today's Agenda-• SLO pretest• Lab safety guidelines


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August 12, 2015

Aug 6 2014


Today's Agenda-• Lab safety procedures• Lab safety cartoon• Lab safety Meme (homework)

Warm-up:What is the most dangerous thing in a chemistry class?

Aug 61:30 PM


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August 12, 2015

Aug 8 2014


Warmup:What happens when you violate a lab safety procedure the first time? The second? Is this just or unjust? Defend your answer.

Today's Agenda-• Equipment Scavenger Hunt

LAB ON MONDAY

Aug 72:44 PM


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August 12, 2015

Aug 9 2014


Warmup:What equipment are we using in the lab tomorrow?

Today's Agenda-• Safety Quiz• Review Lab equipment• Pre-lab discussion (LAB tomorrow)

Aug 11 2013


Warmup:Would you rather have about a million dollars or exactly a million dollars. Justify your answer.

Today's Agenda-• Safety and Lab Equipment Quiz• Grade lab• Use lab to discuss how to measure in chemistry using accuracy and precision


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August 12, 2015

Aug 13

Today's Agenda:• Discuss accuracy and precision in measurement• Significant digits

Mrs. FreemanHonors Chemistry Aug. 12, 2015

Warmup: What is the measurement of the following items in cm? In mm?

Aug 311:46 AM

Base unit-a defined unit of measurement based on an object or event in the physical world

Derived unit-a unit of measurement defined by a combination of base units

Four base units:TimeLengthMass Temperature

Volume Density


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August 12, 2015

Aug 78:20 AM

In science we use the SI Units(International system) for measuringMeasurements

Aug 57:53 AM

Accuracy: How close to a measured value is to an accepted value.

Precision: How close a series of measurements are to one another


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August 12, 2015

Aug 78:21 AM

Instruments have a certain level of accuracy

To be accurate always estimate another digit after last certain digit. this is called your estimated digit.WHY?

We know that this measurement is somewhere between 105 and 106. So our estimated value would be the tenths place Measurement would be around 105.5 ml

Measurements

How did we see this in the lab?

Aug 78:29 AM

0.0078956700700713404.40500045010.0980010050005602315

Which numbers were taken from the most accurate instrument?

Which numbers were taken from the least accurate instrument?

How do you know?

Warmup

Which number was just an estimate? Were any of its numbers certain? So how many of its digits are significant?


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August 12, 2015

Aug 78:22 AM

We are given the 10s and 1s place here, so we will be estimating the 10th place

Measurements

The measurements you are sure of are called certain digits. The last unit is an estimate. They all tell you something, so they are SIGNIFICANT.

Instruments have a certain level of accuracy

To be accurate always estimate another digit after last certain digit. This is called your estimated digit

Aug 78:22 AM

PracticeMeasurements


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August 12, 2015

Aug 67:39 AM

• Only measurements have sig figs. Why?• Sig figs are all measured numbers plus one estimated

digit. • When we measure something, we can (and do) always

estimate between the smallest marks or increments. • The better the marks, the better we can estimate. • When reading a measurement, scientists always understand

that the last number measured is actually an estimate.

Significant figures are numbers that count or mean something in an experiment. They represent the level of certainty in measurement based on the equipment used.

Aug 67:43 AM

Rules for Sig Figs1. All nonzero numbers (naturals) are always significant

If it is not a natural number then it must follow other rules...

(a) 456 (b) 35 (c) 4 (d) 891

(e) 1,345 (f) 12,345 (g) 4.52Rules for zero:


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August 12, 2015

Aug 67:56 AM

5)Counting numbers and conversion factors have infinite numbers of significant figures

3) All final zeros to the right of the decimal (and after a nonzero number) are significant

4) Placeholder zeros are not significant (all other zeros)

Rules for Sig Figs cont.

"AFTER, AFTER"

Rules for zero:2) Zeros between two nonzero numbers are always significant

"TRAPPED!"

Aug 67:12 AM

The AtlanticPacific Trick

Pacific "point"

Atlantic"no point"3.04500

304500

100.0100


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August 12, 2015

Aug 78:29 AM

0.0078956700700713404.40500045010.0980010050005602315

WarmupHow many sig figs?

Aug 98:03 AM

MULTIPLICATION and DIVISION

• Multiply or divide normally following the order of operations• The answer must contain the same number of significant figures as the number with the least significant figures.• Round to that number.

What is the density of a metal block that has a mass of 34.5 g and a volume of 13 mL?

Example:


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August 12, 2015

Aug 99:58 AM

Practice:

a. 31.5 * 56b. 14.8 / 45c. 100 * 56.7d. 9870 / 89.0e. 99.9909 /10.0

Aug 98:00 AM

• When adding numbers, align the decimals.• The answer must contain the same number of sig figs after the decimal as the number with the least amount of sig figs to the right of the decimal. Why?• Round to that number.

ADDITION and SUBTRACTION

Felix added 15.66 grams to the solution of that had a mass of 50 grams. What was the final mass?


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August 12, 2015

Aug 99:58 AM

Practice:

a. 31.5 + 56.890b. 124.8 - 45c. 100.00 + 56.7d. 9870 + 89.03e. 99.9909 -10.0

Aug 98:56 PM

Scientific Notation

Scientific notation is a form of writing numbers that are too large or too small to be written practically using placeholders.

It is also used to express numbers that cannot be written in standard notation and still have the correct amount of sig figs.


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August 12, 2015

Aug 99:27 PM

To convert from standard notation to scientific notation...

1. Move the decimal to the right of the first sig fig.2. Remove all non significant zeroes3. Write "X 10" beside the number4. Count how many places the decimal moved and write that

number as an exponent above the 105. If the original number was a decimal, the exponent is negative6. If the original number was NOT a decimal, the exponent is positive.

Aug 67:52 AM

Scientific Notation

a) 0.00000305

b) 102,000,000,000

c) 0.00000678000

d) 45000

e) 609.00

Practice: Put the following numbers in sci. notation


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August 12, 2015

Aug 53:57 PM

Scientific Notation2.34 x 102

4.5 x 105

5.62 x 108

3.45 x 103

1.2 x 106

4 x 104

Practice: Put the following numbers in regular notation

Aug 97:30 PM

Multiplication and Division of Scientific notation

Multiplication:1. Multiply the coefficients2. Add the exponents

EX: (2.25 x 102)( 1.9 x 105)

Division:1. Divide the coefficients2. subtract the exponents

(2.25 x 102) ( 1.9 x 105)


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August 12, 2015

Aug 14

Today's Agenda:• Review significant digits• Multiplying and dividing with sig figs.


Warm‐up: How many sig figs do each of the following numbers have?1.) 98.4357002.) 98,437,7003.) 098,430,070,0004.) 0.0009843007000

Aug 99:42 PM

A. 2.36 x 102 * 1.5 x 105

B. 5.82 x 102 / 3.45 x 103

C. 1.29 x 106 * 4.00 x 104

D. (3.388 x 1010)(9.5 x 103)

E. 1.02 x 108 / 3.165 x 102

F. (4.20 x 104)(4 x 104)

Examples:


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August 12, 2015

Aug 97:29 PM

Addition and Subtraction of Scientific notation

1. Make the exponents the same by moving the decimal to the right or to the left.

2. Add (or subtract) the coefficients

Example:

(5.6 x 103) + (4.3 x 104)

Aug 99:45 PM

A. 2.34 x 102 + 4.5 x 105

B. 5.62 x 108 3.45 x 103

C. 1.2 x 106 + 4 x 104

D. 3.388 x 1010 + 9.5 x 103

E. 1.02 x 108 3.165 x 102

F. 4.20 x 104 4 x 104

Examples


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August 12, 2015

Aug 189:38 AM

Aug 15

Today's Agenda:• Warmup • check homework• Dimensional Analysis


Warmup: Complete the following with correct sig figs:1.) 76 / 134.52.) 21.02 + 20.1203.) (0.230 + 2.023)*(4.3 x 106 *1.001)


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August 12, 2015

Aug 181:52 PM

Aug 1811:03 AM


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August 12, 2015

Aug 188:44 AM

Aug 67:32 AM

Error- the difference between an experimental value and an accepted value

Percent error- expresses error as the percentage of the accepted value

error = experimental value - accepted value

percent error = |error| X 100accepted value


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August 12, 2015

Aug 810:22 AM

Bertha and Skeeter conducted an experiment on the amount of CO2 produced by three moles of CH4 and a liter of O2. They conducted their trials five different times. Below is their data.

trials: grams error? % error?1 129.52 124.63 128.04 127.05 120.2

According to their calculations they should have produced 132.2 grams

Aug 1310:21 AM

Two kinds of data or observations:Qualitative data: data that is more anecdotal and cannot or is not be measured, describes the qualities of somethingExample: shiny, blue, soft, viscous, etc.

Quantitative data:measurements recorded from experiments


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August 12, 2015

Aug 132:36 PM

Dimensional Analysis is a method of using conversion factors to convert from one unit to another.

A conversion factor is a ratio of two factors that equal each other.Ex: one inch = 2.54 cm

Dimensional Analysis

We do NOT use sig figs of conversion factors

Aug 188:50 AM

1. start with your given,2. Line up your units3. put in your numbers4. multiply across

5. divide top by bottom

6. Round answer to S.F.


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August 12, 2015

Aug 149:25 AM

Since both measurements in a conversion factor equal the exact same distance we can put them over each other and they equal one.

In math anything can be multiplied by one without changing the quantity. Therefore we can multiply by conversion factors to conveniently switch from one unit to another.

0.62 miles

1 kmor

0.62 miles

1 km

Example 2: 0.62 miles = 1 km

If I traveled I16.72 miles, how many meters did I go?

Aug 189:01 AM

16 oz = 1 lb4.448 lbs = 1 Newtonµ= micro

`


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August 12, 2015

Aug 1810:05 AM

How many mg are in 0.340 lbs?1 kg = 2.2 lbs

Aug 1811:37 AM


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August 12, 2015

Aug 1811:46 AM

Aug 282:01 PM

1. Working in the laboratory, a student finds the density of a piece of pure bismuth to be 9.67 g/cm3. The accepted value for the density of bismuth is 9.78 g/cm3. Calculate the student's percent error?


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August 12, 2015

Aug 149:31 AM

Practice:

A. How many mL in .0034 L?

B. How many mg in 93 kg?

C. How many meters in 6.5 X 104 μm?

Aug 13

Today's Agenda:• Check homework• Lab TOmorrow!


Warmup: (hola) Complete the following, express in scientific notation with correct sig fig:1.) 7.89 x 105 * 3.014 x 101

2.) (1.45 x 103 lbs)/(2.667 x 107 gallons) How many g/ml?3.) (2.305 x 1010 miles)/(4.5 x101 hours) How many meters per second?

1 gallon = 3.78541178 liters0.62 miles = one km

2.2 lbs = 1Kg


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August 12, 2015

Aug 282:07 PM

Aug 277:48 AM

2.) (1.45 x 103 lbs)/(2.667 x 107 gallons) How many g/ml?


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August 12, 2015

Aug 199:03 AM

Aug 2710:01 AM


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August 12, 2015

Aug 1310:35 AM

Reading Quiz:

1. Name 3 base units:a.b.c.

2. What illustration was used in the book to explain precision?

3. Challenge: If you add or subtract sig figs, how many sig figs to the right of a decimal should you have?

Aug 121:19 PM

Make a mind map

about...

Warmup:


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August 12, 2015

Aug 2210:33 AM

Today's Agenda- SLO pretest Lab safety ... - Honors Chemistryknightshonorschem.weebly.com/uploads/3/7/2/4/... · Measurement Honors Chemistry (2).notebook 4 August 12, 2015 Aug 9

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