4/24/2017 11:54 PM Accuracy = of a measurement is how close that measurement is to the true or “exact” value EX: Standard weight = 5.00g 4.98g more accurate.

Slides:

Advertisements

Similar presentations

Measurements with Range Uncertainty CHEMISTRY 11 UNIT 1.3.

Advertisements

Measuring Reading the Meniscus Always read volume from the bottom of the meniscus at eye-level. The meniscus is the curved surface of a liquid in a narrow.

Measurements Length Volume Temperature Mass 1.Will learn to use different measuring instrument 2.Will learn that the smaller the unit increment, the more.

INTRODUCTION TO PIPETTES

Pipetting Pipetting involves drawing a liquid into a pipet and allowing liquid to drain from the pipet in a controlled manner. Pipetting is used to quantitatively.

Laboratory Techniques I: Dilution Go to browse and set to full screen.

Error Analysis. As a scientist you must make the best effort to avoid errors! Errors may be present in: - the design of the experiment. -the use of instruments.

Measurements Chemistry Department Minneapolis Community & Technical College Intro to Chemistry Chem1020 Lab 1.

Forensic Science.   Part 1 - number  Part 2 - scale (unit)  Examples:  20 grams  6.63 x Joule seconds Measurement - quantitative observation.

Types of Numbers (Data)

Measuring  Volume  Temperature  Mass. Reading the Meniscus Always read volume from the bottom of the meniscus. The meniscus is the curved surface of.

Questions to think about… How would you describe the importance of accuracy and precision in experimentation? How is precision connected to experimental.

Making Measurements and Reading Scales

Measurements: Precision, Accuracy and Uncertainty

MEASUREMENT Cartoon courtesy of Lab-initio.com.

1 Determining Mass Mass is a direct measurement of the amount of matter in a sample.

Common Laboratory Glassware and Volumetric Glassware Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit.

MLAB 1335 Immunology Serology Terry Kotrla, MS, MT(ASCP)BB

Introduction to the most commonly used glassware and equipments in the lab.

CHEM General Chemistry I Laboratory - Fall 2011

Lab Techniques How to do a Manual Titration. Rinse the inside of the Burette Rinse the burette with 2-3 mLs of standarized NaOH solution. Make sure all.

How to do a Manual Titration. Rinse the Burette with 2-3 mL of standardized NaOH solution. Make sure all inside walls including the tip are rinsed. Discard.

COMMON LABORATORY EQUIPMENT. FLASKS, BEAKERS, CYLINDERS Erlenmeyer flask beaker Erlenmeyer flasks and beakers are used for mixing, transporting, and reacting,

Topic 11: Measurement and Data Processing

Unit 1: Introduction to Chemistry Please enjoy this free measurement Power Point. If you like the quality of my work, please stop by my TpT store for.

MLAB 1335 Immunology Serology Terry Kotrla, MS, MT(ASCP)BB

Chapter 2 Measurement & Problem Solving. Uncertainty There is a certain amount of doubt in every measurement – It is important to know the uncertainty.

1 Using Numbers in Science Metric System and Instruments Used for Measurement.

Identification of the common laboratory glassware, pipettes and Equipment . BCH 312 [PRACTICAL]

Measurements and Calculations 1. To show how very large or very small numbers can be expressed in scientific notation 2. To learn the English, metric,

1 Parts of a Measurement 1.The value (numerical portion) 2.The unit (describes what units) 3.The name of substance being measured EX: 1 teaspoon salt 2.

Scientific Measurements “measurement” could be defined as the process or the result of determining the magnitude of a quantity. Measurements can be made.

Flashback Convert 2.58 m to kilometers. Accuracy and Precision Accuracy- the closeness of measurements to the correct value of the quantity measured.

Reading Scales Section 1.3. Our Metric Rulers are Marked off in Centimeters 10 centimeters are in one decimeter.

Some Common Laboratory Glassware Please be careful when using glassware in the laboratory. Wet glassware and wet gloves are slippery. Always read a volume.

Uncertainty and Error in Measurement (IB text - Ch 11) (If reviewing this slide in the senior year, there is also uncertainty information in the AP text.

1 Accuracy and Precision Notes Chemistry 1. 2 Uncertainty in Measurements There is no such thing as a perfect measurement! All measurements have a degree.

Chapter 1 Chemical Foundations. Section 1.4 Uncertainty in Measurement 2 Return to TOC Copyright © Cengage Learning. All rights reserved Precision and.

1 Multi Beam Balance. 3 Here are the steps for using a multi-beam balance properly: Adjust all riders, so that each reads zero. Then check to make sure.

I. Types of Errors: Systematic Random

The Beginning.  Identification/usage of glassware and equipment  When diluting acids ALWAYS add the acid to the water to prevent spattering due to heat.

Introduction The Equipment The Terms The Process Calculations

Measurements: Precision, Accuracy and Uncertainty.

Volume determination and density

© SSER Ltd. How Science Works Selecting & Using Apparatus.

 Most common for holding liquids  Hold solids or liquids that are unlikely to release gas or splatter if stirred or heated.  Beakers come in several.

Section 2-3 Section 2.3 Uncertainty in Data Define and compare accuracy and precision. Describe the accuracy of experimental data using error and percent.

LABORATORY GLASSWARE AND EQUIPMENT LAB 2. Welcome Welcome to the chemistry lab! Chemistry is a lot of fun, but can be even more so if you are familiar.

Uncertainty in Measurement How would you measure 9 ml most precisely? What is the volume being measured here? What is the uncertainty measurement? For.

Used to communicate the accuracy of measurements

Significant Figures Show the Uncertainty in Measured Data

How big is the beetle? Measure between the head and the tail!

BELLWORK 9/13/16 1 Tm = 1012 m 1mm = 10-3 m 1Mm = 106 m

How to do a Manual Titration

Significant Figures Show the Uncertainty in Measured Data

OPENING ROUTINE A material will float on the surface of a liquid if the material has a density less than that of the liquid. Given that the density of.

MLAB 1335 Immunology Serology Terry Kotrla, MS, MT(ASCP)BB

Lab Techniques How to do a Titration.

Measurement of Volume Chapter 20.

Accuracy and Precision

How to do a Manual Titration

Identification of the common laboratory glassware, pipettes and instruments . BCH 312 [PRACTICAL]

BELLWORK 9/2/15 How does a scientist reduce the frequency of human error and minimize a lack of accuracy? A. Take repeated measurements B. Use the same.

Accuracy and Precision

Common Laboratory Glassware

Accuracy and Precision

Laboratory Glassware.

Identification of the common laboratory glassware, pipettes and instruments . BCH 312 [PRACTICAL]

Accuracy and Precision

Presentation transcript:

4/24/2017 11:54 PM Accuracy = of a measurement is how close that measurement is to the true or “exact” value EX: Standard weight = 5.00g 4.98g more accurate than 5.12 g Accuracy is also subject to the reliability of the measuring instrument. 1

4/24/2017 11:54 PM Precision Precision = making reproducible or repetitive measurements of the same quantity How fine the divisions are There will always be some uncertainty because of the limits in the accuracy of your instruments 2

Determining the % Accuracy of a Balance 4/24/2017 11:54 PM Determining the % Accuracy of a Balance All balances DO NOT measure items with the same precision. Accuracy can be expressed in two ways: 1. % accuracy = indicates how close the experimental value is to the standard or reference value 2. % error = describes hour far off the experimental value is from the stander or reference value. 3

Determining the % Accuracy of a Balance 4/24/2017 11:54 PM Determining the % Accuracy of a Balance To calculate the % accuracy of the balance you are using % Accuracy = experimental value X 100% reference or standard value The larger this value, the greater the degree of accuracy. 4

Determining the % ERROR of a Balance 4/24/2017 11:54 PM Determining the % ERROR of a Balance To calculate the % error of the balance you are using % error = standard mass – experimental mass X 100% standard mass The smaller this value, the greater the degree of accuracy. 5

4/24/2017 11:54 PM Absolute Value = considered the amount of mass difference between zero and the determined mass - you are determining how far “off” the standard the mass is - recorded as a positive answer even if the value resulted in a negative number 6

Comparing % Accuracy of Multi Beam Balance and Digital Balances 4/24/2017 11:54 PM Comparing % Accuracy of Multi Beam Balance and Digital Balances % Accuracy = experimental value X 100% reference or standard value 7

Precision of Repeated Measurements By Pipetting Pipetting involves drawing a liquid into a pipet and allowing liquid to drain from the pipet in a controlled manner. Pipetting is used to quantitatively transfer exact volumes of a liquid from one container to another.

Mohr pipet Has graduations that allow it to deliver a range of volumes.

That means you let all the (measured) liquid in the pipet exit. Serological pipets have no base mark (the graduations continue onto the tip) and are graduated to deliver. That means you let all the (measured) liquid in the pipet exit. Graduated to the tip

The volumetric pipet has a single graduation that allows it to deliver one specific volume accurately.

Reading a Pipette Smallest Unit Increment Total Volume

Reading the Volume Determine the volume of solution in a pipet by reading the bottom of the meniscus at eye level. Record the volume 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. What are the volumes in these pipets?

Reading a Pipet

What is wrong with this pipet reading?

Dispensing Liquid Accurately transferring a specified volume of liquid from one container to another requires careful attention to detail. Pay special attention to the level of liquid in the pipet and carefully monitor the meniscus.

3-Way Safety Bulb

Using a 3-Way Safety Bulb Make sure there is enough solution in your beaker to completely fill the pipet. Never pipet a reagent directly from a reagent bottle. Carefully place the attachment of the three-way bulb over the mouth of the pipet.

Squeeze the air valve (A) and the bulb simultaneously to empty the bulb of air. Place the tip of the pipet below the solution's surface in the beaker. Gradually squeeze the suction valve (S) to draw liquid into the pipet. If the level of the solution is not high enough, squeeze the air valve (A) and the bulb again to expel the air from the bulb. Draw up more liquid by squeezing the suction valve (S).

When the liquid is above the specified volume, stop squeezing the suction valve (S). Do not remove the bulb from the pipet. Do not allow liquid to enter the pipet bulb. Use the expel (E) valve to release the solution.