WELCOME TO CHEM 14BL!
WELCOME TO CHEM 14BL!
sample preview covering Business, Essay, Bachelors, APA 7th Edition.
Take a few minutes to introduce yourselves to your neighbors before we get started. WELCOME TO CHEM 14BL!
CHEM 14BL - Fall 2025 General Information* Instructor: Chau Ngo, Ph.D. Email: chaudngo@g.ucla.edu Office: 4222B Young Hall Office Hours: Tues 10 – 11AM Thurs 9 – 10 AM Lectures: Tuesday 8 – 8:50 am CS50 (Lecture 1) Tuesday 9 – 9:50 am CS50 (Lecture 2) Lab Rooms: 1077, 1089 and 1337 Young Hall *All info can also be found in the course syllabus via Bruin Learn
Enforced Requisites for the CHEM 14BL To receive credit for the class, students must have the following requisites 1. 14A or 14AE (Completed with C - or higher) AND 2. 14B or 14BE (Concurrent Enrollment OR Completed with C - or higher)
Required Materials for CHEM 14BL 1. Physical Laboratory Manual (Required Textbook) • Chemistry Experiments for Life Science Major (5 th Edition only) 2. Laboratory Notebook with Duplicate Pages • Notebook with duplicate carbon pages (50 or 100 Pages) 3. PPE • Safety Glasses/ Goggles • Flame - Resistant Blue Lab Coat • Long pants • Closed - toe shoes
PPE P ersonal P rotective E quipment Safety Glasses Flame - resistant Lab Coat Long Pants (ankle length) Without holes or tears Closed - Toe Shoes Gloves (will be provided In the lab ) Face Covering (Recommended)
Laboratory Safety Reminder ➢ A physical lab manual, a lab notebook and proper PPE are required for attending and performing experiments starting week 2. ➢ Failure to meet the safety requirements will result in dismissal from the lab without make - up lab time . ➢ Repeat violation in safety policy will result in a failing grade (“F”) in the course .
TV Show (CBS): The Big Bang Theory
NFPA N ational F ire P rotection A ssociation
Course Grade Policy Read the syllabus on minimum passing grade requirement 1. Pre - lab Reports - Weekly guidelines will be posted every Wednesday prior to the next lab session 2. In - lab Performance including satisfactory lab cleanup 3. Post - lab Reports - Weekly guidelines will be posted every Wednesday prior to the next lab session 4. Online Midterm 5. In - Person Final Exam
Course Grade Policy Read the syllabus on minimum passing grade requirement 1. Pre - lab Reports - Weekly guidelines will be posted every Wednesday prior to the next lab session 2. In - lab Performance including satisfactory lab cleanup 3. Post - lab Reports - Weekly guidelines will be posted every Wednesday prior to the next lab session 4. Online Midterm Oct. 30 (Noon, PST) – 31 (9 PM, PST) 5. In - Person Final Exam Dec. 09_6:30 – 9:30 PM
CHEM 14BL is an Impacted Course LAST DAY TO DROP THE COURSE: THE FRIDAY OF THE SECOND WEEK Oct. 10
Questions Detailed course info is available via Bruin Learn.
Week 1: Sept. 30 – Oct. 03 Measurements and Errors
Measurements and Errors In scientific analysis, one often wants to know how reliable a particular measurement is besides its value.
Accuracy and Precision ❖ Accuracy defines the closeness of a set of results to the true value. ❖ Precision defines the closeness of a set of results to each other (i.e. results should be “reproducible” in science)
Yellow Circle = Target area X = Experimental data Accuracy and Precision
Measurements and Errors 5.70 mg 6.80 mg 4.90 mg
Random Error vs. Systematic Error Systematic errors result from fundamental flaws in the design, construction, calibration, operation, or interpretation of the experiment . Systematic errors tend to occur in the same direction (i . e . all values too high or all values too low) . Random errors vary arbitrarily in both sign and magnitude between successive measurements .
Examples of Random Error & Systematic Error A. A student consistently read a melting point temperature higher than the actual melting point temperature on a melting - point apparatus. B. A student used a contaminated solid compound when measuring its melting point.
How do we estimate errors in experiment?
Absolute Error vs. Relative Error Example: 5.0cm ± 0.1cm (i.e. Range between 4.9 and 5.1cm)
Absolute Error vs. Relative Error Example: 5.0cm ± 0.1cm (i.e. Range between 4.9 and 5.1cm) ❖ Absolute Error : ± 0.1 cm • Same unit as the measurement • Same number of decimal places as the measurement ❖ % Relative Error % Relative Error = 𝐴𝑏𝑠𝑜𝑙𝑢𝑡𝑒 𝐸𝑟𝑟𝑜𝑟 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑚𝑒𝑛𝑡 × 100% ❖ “ ± ” sign does NOT go into the calculation. It is just a symbolic representation of an error.
General Rules for Error Propagation ❖ Multiplication and/or Division C = A × B or C = A ÷ B • A & B are the experimental measurements
General Rules for Error Propagation ❖ Multiplication and/or Division C = A × B or C = A ÷ B • A & B are the experimental measurements 1. Relative Error in C : B B A A C C + = • where A and B are the absolute errors in the quantity A and B. • Equation can be generalized to more than two terms.
General Rules for Error Propagation ❖ Multiplication and/or Division C = A × B or C = A ÷ B • A & B are the experimental measurements 1. Relative Error in C : B B A A C C + = C B B A A C + = • where A and B are the absolute errors in the quantity A and B. • Equation can be generalized to more than two terms. 2. Absolute Error in C :
) 0002 . 0 4000 . 0 ( ) 02 . 0 00 . 5 ( 1. Relative error: Example 1: Calculate % relative error and absolute error of (C = A × B)
) 0002 . 0 4000 . 0 ( ) 02 . 0 00 . 5 ( 2. Absolute error: Example 1: (C = A × B)
General Rules for Error Propagation ❖ Addition and/or Subtraction C = A + B or C = A - B • A & B are the experimental measurements
General Rules for Error Propagation ❖ Addition and/or Subtraction C = A + B or C = A - B • A & B are the experimental measurements 1. Relative Error in C : • where A and B are the absolute errors in the quantity A and B. • Equation can be generalized to more than two terms. C C = A C + B C
General Rules for Error Propagation ❖ Addition and/or Subtraction C = A + B or C = A - B • A & B are the experimental measurements 1. Relative Error in C : • where A and B are the absolute errors in the quantity A and B. • Equation can be generalized to more than two terms. C C = A C + B C 2. Absolute Error in C : C C B C A C + =
1. Relative Error: ) 02 . 0 40 . 0 ( ) 02 . 0 05 . 5 ( − Example 1: Calculate % relative error and absolute error of (C = A - B)
2. Absolute Error: ) 02 . 0 40 . 0 ( ) 02 . 0 05 . 5 ( − Example 2: (C = A - B)
Additional Practice Problems on Error Analysis (Work on them on your own)
Determine the % relative error and absolute error for the following calculation Step 1: Check the mathematical operation in the calculation Addition and Subtraction Step 2: Based on step 2, use the appropriate equation for % relative error Practice Problem #1 2.51 + 1.67 – 0.58
( 0.0953M ± 𝟎 . 𝟎𝟎𝟎𝟏𝑴 ) × (20.23mL ± 𝟎 . 𝟎𝟑𝒎𝑳 ) ( 10.00mL ± 𝟎 . 𝟎𝟒𝒎𝑳 ) Step 1: Check the mathematical operation in the calculation Multiplication and Division Step 2: Based on step 2, use the appropriate equation for % relative error Practice Problem #2 Determine the % relative error and absolute error for the following calculation
Reminders for Week 1, Sept. 30 – Oct. 03 ➢ Show up ON TIME to the correct enrolled or wait - listed section • If you have informed me with your lab switch, please join your new lab session . ➢ Spots of enrolled students that are more than 15 - min late to the first lab will be re - assigned to students on the waiting list . ➢ PPE, lab notebook and lab manual are not required in the lab during week 1
Reminders for Week 2, Oct. 07 – 10 Assignments that are due in lab 1. MSDS/ NFPA Exercise 2. Pre - lab assignment for the “Pipet Calibration” lab Check the guidelines via Bruin Learn Follow standard laboratory PPE safety policy
