Chemistry Lab Report Guide The Writing Center Before you ...
Writing a Lab Report
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Transcript of Writing a Lab Report
Writing a Lab Report
Introduction• Background Information
– What you already know, research, related information, etc.
• Observations– Feel, Touch, Appearance, etc.– Be Consistent
• Problem– Experimental question.
• Hypothesis– Possible explanation for a set of observations.– Your statement must relate to the problem and why you feel
that way (Experience, Background Information, and Observations.
Procedure
• Materials– Equipment and anything else used to carry
out the present experiment.– Do not write “Pen” or “Paper”
• Methods– Experimental design, exact procedure
followed.– Someone else should be able to do precisely
what you did.
Results and Discussion
• Data Collected– Graphs, Data Table and Text reporting findings.– You need to have a TABLE, a GRAPH, and
PARAGRAPHS reporting your data.
• Discussion and explanation of findings.– Interpret data and explain HOW and WHY your
data was as it is.– Explain Everything!
Conclusions• Brief Summary of Important Data.• Was your hypothesis proved? Why?
– Support your answer
• Causes of possible error or uncertainty regarding any portion of the experiment.– If there is none, say that.
• Your expert opinion of Why and How the results were as you found them to be.– Take some guesses, Go out on a limb.
• Recommendations for future researchers and other related studies that should be done.– What else needs to be studied to gain a better
understanding of the current material?
Paper Towel Absorbency Test
Towel Area (sq cm)
Amount of Water Absorbed
trial 1 (ml) trial 2 (ml)
Fold 15 x 15 cm 225 32 33
20 x 20 cm 400 42 43
Bounty 15 x 15 cm 225 52 53
20 x 20 cm 400 62 63
Standard 15 x 15 cm 225 12 13
20 x 20 cm 400 22 23
Paper Towel Absorbency TestCreate a Title For this Graph
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0 50 100 150 200 250 300 350 400 450
Label Your Independent Variable
Lab
el Y
ou
r D
epen
den
t V
aria
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Fold 15 x 15 cm Fold 20 x 20 cm Bounty 15 x 15 cm Bounty 20 x 20 cm Standard 15 x 15 cm Standard 20 x 20 cm
Scientific Notation
Scientific Notation
• 299,800,000 m/sec is the speed of light in a vacuum
• 602,000,000,000,000,000,000,000 is the number of atoms in 1 mol Carbon
• 0.000000000000000000000001674 g is the mass of one hydrogen atom
Scientific Notation
it is extremely cumbersome to do calculations with very large and small numbers so…
c x 10n
where c is the coefficient and n is the exponent
Scientific Notation
• 2.998 x 108 m/sec (the speed of light in a vacuum)
• 6.02 x 1023 atoms (the number of atoms in 1 mol of carbon)
• 1.674 x 10-24 g (the mass of one hydrogen atom)
Scientific Notation
1. Move the decimal point so that there is only one digit to the left of the decimal.
2. Count the number of places the decimal moves.
3. If the decimal moves to the left, the exponent on 10 is equal to the number of places the decimal was moved and has a positive sign.
4. If the decimal moves to the right, the exponent on 10 is equal to the number of places the decimal was moved and has a negative sign.
Practice Problems
7,910,000
.00000000345
1,200,000,000.0
.000098
Practice Problems
0.00416 x 106
24.8 x 10-3
0.716 x 10-4
3410 x 102
Significant Figures
Sig Figs
Significant Figures
Used to convey the confidence we have in the accuracy of our measuring methods
and measurements
8 ± 1 mL (beaker)
8.0 ± 0.1 mL (graduated cylinder)
8.00 ± 0.01 mL (buret)
How many sig figs are in the following???
23.4g 555001.0100 atoms
200mL 74.221g
3.100mm 0.001201kg
Significant Figures
Rules for Sig Fig
Rule 1
Zeros between other nonzero digits are significant.
Examples
a. 50.3 m has three significant figuresb. 3.0025 s has five significant figures
Rules for Sig Fig
Rule 2
Zeros in front of nonzero digits are not significant.
Examples
a. 0.892 has three significant figuresb. 0.0008 s has one significant figure
Rules for Sig Fig
Rule 3
Zeros that are at the end of a number and also to the right of a decimal point are significant.
Examples
a. 57.00 g has four significant figuresb. 2.000 000 kg has seven significant figure
Rules for Sig Fig
Rule 4
Zeros that are at the end of a number but left of the decimal point are not significant.
Examples
a. 100 m has ONE significant figureb. 20 m has ONE significant figure
Rules for Sig. Fig.
Extra Rule
Zeros that are at the end of a number but left of the decimal point that are measured to be significant are indeed significant.
Examples
a. A scale measures 1200. kg has four significant figures and is written in scientific notation:
1.200 x 10 kg so Rule 3 applies3
Rules for Sig Fig
Put the following into scientific notation…
23.4g 555001.0100 atoms
200mL 74.221g
3.100mm 0.001201kg
Significant Figures
Significant Figures
Round the following to the indicated number of significant figures.
23.4 g (2 sig figs)
555001.0100 atoms (3 sig figs)
2001.0345mL (5 sig figs)
74.221g (3 sig figs)
3.100mm (3 sig figs)
0.001201kg (3 sig figs)
Rules for Calculating with Significant Figures