1. CHEM 1111 General Chemistry I Laboratory - Fall 2011
TA’s Contact Information
Name : Imalka Munaweera
Office : SLC 3.409
Address :
Office Hour : Friday 11 a.m -12 p.m

2. General Course Information
Course Description
These courses reinforce the concepts of Freshman Chemistry in the
lab via experiments.
Students are offered the opportunity to acquire basic laboratory
skills and an appreciation for the presence of chemistry in daily living.
The experiments are designed to demonstrate concepts including
properties of inorganic substances, principles of structure and bonding,
and elementary quantitative analysis.

3. Required Texts & Materials
Laboratory Manual for General Chemistry laboratory I (CHEM 1111)
ISBN:
Z-87 rated Safety Glasses or Goggles
Combination Locks
A Composition Notebook and a Calculator
Students are financially responsible for items checked out
of the stockroom

4. Class Attendance
It is typical for the laboratory activities to utilize the entire 180 minutes of
class time such that one can not simultaneously enroll in other classes
whose meeting days and times conflict with those of CHEM 1112.
No cell phones or computers are allowed in the chemistry laboratories.
If you need to make an emergency phone call, please step outside.

5. Make-Up Labs Workshops
There are no make-up lab dates for any experiments!
Workshops
Students will work in groups during the first 45 min of the lab period.
Workshops count for 10% of the course grade.

6. Safety
IMPORTANT: In accordance with University and Chemistry Department safety rules, any time anyone is in a lab, Z87-rated safety eyewear must be worn.

7. Summary of Points: Pts. Lab Readiness 10 Lab Write Ups 70 Total 100
Notebook/workshops 20
Lab Readiness 10
Lab Write Ups 70
Total
For details please see grade breakdown for each experiment.
Grading (credit) Criteria

8. Measurements Mass measurement Mass
Mass is the amount of matter in something
In the metric system mass is measured in kilograms and grams
Mass measurement

9. Volume Volume measurement A graduated cylinder A pipette
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid or gas) or shape occupies or contains.
The metric system includes the liter (L) and milliliter (ml) as a unit of volume
Volume measurement
A graduated cylinder
A pipette

10. Graduated Cylinder
Graduated Cylinder is an instrument used to transfer liquids. Graduated cylinders come in various sizes.

11. Pipette
A pipette is an instrument used to transfer liquids. Pipettes come in various sizes.
Pipetting is used to quantitatively transfer exact volumes of a liquid from one container to another.
Pipettes are loaded using pipette pumps. The pipette pumps commonly encountered are either rollers or bulbs.

12. Reading the meniscus correctly

13. Certain digits are obtained from calibration marks.
The volume of solution in a pipette is determined by reading the bottom of the meniscus at eye level.
The volume is recorded by using all certain digits and one uncertain digit.
Certain digits are obtained from calibration marks.
Uncertain digits (the last digit in the number) are estimated
between calibration marks.
Some examples are shown below:
5.00 mL reading
4.49 mL reading
4.88 mL reading

14. Significant figures
The significant figures (also called significant digits) of a number are those digits that carry meaning contributing to its precision.
A digit is a symbol (a numeral symbol such as "3" or "7") used in combinations (such as "37") to represent numbers in positional numeral systems.
The precision of a measurement system, also called reproducibility or repeatability is the degree to which repeated measurements under unchanged conditions show the same results.

15. Identifying significant digits
The rules for identifying significant digits when writing or interpreting numbers are as follows:
All non-zero digits are considered significant.
Example, 91 has two significant digits (9 and 1), while has five significant digits (1, 2, 3, 4 and 5).
Zeros appearing anywhere between two non-zero digits are significant.
Example: has five significant digits: 1, 0, 1, 1 and 2.
Leading zeros are not significant.
Example, has two significant digits: 5 and 2.
Trailing zeros in a number containing a decimal point are significant.
Example, has six significant digits: 1, 2, 2, 3, 0 and 0.
The number still has only six significant digits (the zeros before the 1 are not significant). In addition, has five significant digits.
This convention clarifies the accuracy of such numbers; for example, if a result accurate to four decimal places is given as then it might be understood that only two decimal places of accuracy are available. Stating the result as makes clear that it is accurate to four decimal places.

16. Multiplication or Division
Keep the same number of sig figs as the factor with the least number of sig figs.
Example: 1.2 x 4.56 = on the calculator.
But since the one factor has only 2 sig figs, the answer must be rounded to 2 sig figs or 5.5.
Addition or Subtraction
Keep the same number of decimal places as the factor with the least amount.
Example: = on the calculator.
But since the one factor has only 2 decimal places, so must the answer.
Thus the result must be rounded to 6.90 (where the zero is significant )

17. Let's look at an example where significant figures is important
Measuring volume in the laboratory.
This can be done in many ways: using a beaker with volumes marked on the side,
a graduated cylinder, or a buret.
A rule of thumb: read the volume to 1/10 or 0.1 of the smallest division.
(This rule applies to any measurement.) This means that the error in reading
(called the reading error) is 1/10 or 0.1 of the smallest division on the glassware.
Beaker
The smallest division is 10 mL, so we can read the volume to 1/10 of 10 mL
or 1 mL. The volume we read from the beaker has a reading error of + 1 mL.
The volume in this beaker is mL. You might have read 46 mL;
your friend might read the volume as 48 mL.
All the answers are correct within the reading error of +1 mL.
So, How many significant figures does our volume of mL have?
Answer - 2! The "4" we know for sure plus the "7" we had to estimate.

18. Graduated cylinder Burette
The smallest division of this graduated cylinder is 1 mL.
Therefore, our reading error will be mL or 1/10 of the smallest
division. An appropriate reading of the volume is mL.
An equally precise value would be 36.6 mL or 36.4 mL.
How many significant figures does our answer have? 3!
The "3" and the "6" we know for sure and the "5" we had to estimate a little.
Burette
The smallest division in this buret is 0.1 mL. Therefore, our reading
error is mL. A good volume reading is mL.
An equally precise answer would be mL or mL.
How many significant figures does our answer have? 4!
The "2", "0", and "3" we definitely know and the "8" we had to estimate.

19. Let’s enjoy the lab sessions