Calculating Percent Error. What is it?? Percent Error is used to determine the inaccuracy, in percentage, of a measured or estimated value, compared to.

Slides:

Advertisements

Similar presentations

Chapter 2 – Scientific Measurement

Advertisements

Calculating Empirical and Molecular Formulas

Accuracy, Precision, Percent Error, & Temperature Scales.

Starter The radius of the moon is 1,737,000 meters. Write this in scientific notation. The diameter of a carbon atom is meters. Write.

Significant Figures. 1.All nonzero digits are significant. Example: 145 (3 sig figs) 2.Zeroes between two significant figures are themselves significant.

Using Scientific Measurements.

Significant Figures Unit 1 Presentation 3. Scientific Notation The number of atoms in 12 g of carbon: 602,200,000,000,000,000,000, x The.

Scientific Measurement What is measurement… What is measurement… Measurement is a quantity that has both a number and a unit. Measurement is a quantity.

Percent Composition. What is Percent Composition?  The percent composition by mass of a compound represents the percent that each element in a compound.

Empirical Formula The empirical formula indicates the ratio of the atoms of an element in a compound.

Calculating Percentage Composition Suppose we wish to find the percent of carbon by mass in oxalic acid – H 2 C 2 O 4. 1.First we calculate the formula.

Using and Expressing Measurements

Safety and Measurement Starting with the basics. Lab Safety  Remember that the lab is a place for serious work!  Careless behavior may endanger yourself.

Words to Know Qualitative measurements – results are in a descriptive, nonnumeric form (Forehead feels hot) Quantitative – results are in a definite form,

Measurements: Every measurement has UNITS.

Afra Khanani Period 6 Honors Chemistry March 31 st.

Measuring and Units.

Chapter 2 “Scientific Measurement” Standards for Measurement Accuracy vs. Precision Significant Figures.

Using Scientific Measurements. Uncertainty in Measurements All measurements have uncertainty. 1.Measurements involve estimation by the person making the.

Mr. Ramos.  Chemistry is the study of matter, and matter is the stuff things are made of.  Matter is anything that takes up space and has mass.  All.

Accuracy, Precision, Percent Error. Accuracy How close a measured value is to an accepted value - Accuracy can be determined by just on measurement -Depends.

Multiplying and Dividing by Powers of 10; Scientific Notation

CHEMISTRY-CP MIDTERM PROBLEM REVIEW. QUESTION 1 Write in scientific notation. Answers to problem Midterm Math Review Sheet # x

STAAR Ladder to Success Rung 8. How do chemists define a mole? Example #1: A sample consists of 6.85 x atoms of carbon. How many moles does the.

Percent Composition Like all percents: Part x 100 % whole Find the mass of each component, divide by the total mass.

Molar Mass Practice: Molar Mass Practice: 1. Find the molar mass of ammonium sulfate (also called the formula mass): 2. Find the molar mass of copper (II)

Chapter 3 Scientific Measurement Measurement In chemistry, #’s are either very small or very large 1 gram of hydrogen = 602,000,000,000,000,000,000,000.

% by Mass Another way to measure the concentration of a solution % by mass = mass solute x 100 mass solution Solution = solute + solvent.

Unit 2 Unit 2 Percent Error We know that measurements can be described in terms of precision (how close a group of measurements are to each other) and.

Section 10.3 Percent Composition and Chemical Formulas.

Percent Composition. What is it? The percent composition by mass of a compound represents the percent that each element in a compound contributes to the.

Empirical Formula vs. Molecular Formula Empirical formula: the formula for a compound with the smallest whole-number mole ratio of the elements Molecular.

Afra Khanani Period 6 Honors Chemistry March 31 st.

10-3: Empirical and Molecular Formulas. Percentage Composition The mass of each element in a compound, compared to the mass of the entire compound (multiplied.

2.4 Measurement and Significant Figures Every experimental measurement has a degree of uncertainty. The volume, V, at right is certain in the 10’s place,

Mole Theory Percent Composition Yield Problems. Let’s Review… Remember that we can determine the percentage of a defined part by dividing the amount of.

Empirical Formulas Knowing exactly what it is. Percent Composition  Breaks down the amount of an element in a compound by percentage  Total mass of.

Empirical Formula EQ: How is the empirical formula calculated with experimental data?

SOL Review 1.  Accuracy: measure of how close a measurement comes to the actual true value  Precision: measure how close a series of measurements are.

Percent Composition. What is it? Percent composition is the percent by mass of each element present in a compound.

IIIIII II. % Composition and Formula Calculations Ch. 3 – The Mole.

Grams. kilograms Brian estimated the mass of my pet llama to be 95,000 grams. When he placed it on a balance he got a reading of 49 kilograms, what was.

Matter, Measurement, and Problem Solving Reliability of Measurement.

CHAPTER 3 SCIENTIFIC MEASUREMENT. A measurement is a quantity that has both a number and a unit Quantity represents a size, magnitude, or amount Your.

Calculating Percent Error

Accuracy, Precision, Percent Error, & Temperature Scales

Introduction to Chemistry and Measurement

Calculating Percent Error

EMPIRICAL FORMULA VS. MOLECULAR FORMULA .

III. Formula Calculations (p )

The Mole Formula Calculations.

Calculating Percent Error

III. Formula Calculations (p )

Calculating Empirical and Molecular Formulas

Percent Composition, Empirical Formulas, and Molecular Formulas

Percent Composition Empirical Formula Molecular Formula

Lesson 2 – Sci. Notation, Accuracy, and Significant Figures

II. Percent composition

Determining Empirical and Molecular Formulas

III. Formula Calculations

Moles and Formula Mass.

How many moles of water are made by

Calculation Of Molar Mass

II. Percent composition

III. Formula Calculations (p )

Calculating Percent Error

Measurement in Chemistry

Average Atomic Mass.

The Determination of an Empirical Formula

Presentation transcript:

Calculating Percent Error

What is it?? Percent Error is used to determine the inaccuracy, in percentage, of a measured or estimated value, compared to an accepted value.

The Components of the Formula Estimated Value (Measured Value)- The value that has been derived from an experiment, or an estimated value. Actual Value (What you should have gotten!)- This value is the exact value excepted throughout the scientific community, or the value which is determined exact, at a later point in time.

The formula The Formula for Percent Error is a follows: (EV – AV) AV Remember: EV= Estimated Value (measured value!) AV= Actual Value PS. We multiply by 100 to make to make the decimal a percent. X 100 = Percent Error

What does it mean if the PE is positive or negative ? Negative if your measurement is too small Positive if your measurement is too big

Practice Problems Johnny calculates from an experiment that he has 22.7 grams of carbon. However, he should have gotten 21.8 grams of carbon, which was the accepted value for this experiment. What was his percent error? Remember: (EV-AV) X 100 = PE AV

Answer (EV-AV) X 100 = PE AV ( ) X 100 = PE X 100 = PE X 100 = PE 4.13 % = PE

More Practice The actual value for the absorption of carbon is.135. Steven calculated that absorption was.235. What is the percent error in Steven’s experiment?

Answer (EV-AV) X 100 = PE AV ( ) X 100 =PE X 100 = PE X 100 = PE 74.1 % = PE

Additional practice 1. The boiling point of water is 100°C. During an experiment, water came to a boil at 97°C according to the thermometer that was being used. What is the percent error of the thermometer? answer3.0%

Additional practice 2. An experiment was conducted to find the mass of one mole of carbon atoms. The results of the experiment showed that a mole of carbon atoms had a mass of g. The accepted value of a mole of carbon atoms is grams. What is the percent error in this experiment? answer 1.38%

Additional practice 3. An experiment performed to determine the density of lead yields a value of g/cm 3. The accepted value for the density of lead is g/cm 3. Find the percent error. answer 3.46%

Additional practice 4. Find the percent error in a measurement of the boiling point of bromine if the laboratory figure is 40.6°C and the accepted value is 59.35°C. answer %