Newbury Park High School

Newbury Park High School

Science: Chemistry ESLR Assignment

Department: Science

Course Name: Chemistry (CP, H)

Assignment Name: Molar Volume of a Gas

ESLR Focus: Core Knowledge, Critical Thinking, and Effective Communication

California State Standards Addressed:

Investigation and Experimentation Standards:

HSI1. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other four strands, students should develop their own questions and perform investigations. Students will:

HSI1a.Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.

HSI1b.Identify and communicate sources of unavoidable experimental error.

HSI1c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions.

HSI1d. Formulate explanations by using logic and evidence.

HSI1e. Solve scientific problems by using quadratic equations and simple trigonometric, exponential, and logarithmic functions.

HSI1f. Distinguish between hypothesis and theory as scientific terms.

HSI1g. Recognize the usefulness and limitations of models and theories as scientific representations of reality.

HSI1j. Recognize the issues of statistical variability and the need for controlled tests.

HSI1k. Recognize the cumulative nature of scientific evidence.

HSI1l. Analyze situations and solve problems that require combining and applying concepts from more than one area of science.

HSI1m. Investigate a science-based societal issue by researching the literature, analyzing data, and communicating the findings. Examples of issues include irradiation of food, cloning of animals by somatic cell nuclear transfer, choice of energy sources, and land and water use decisions in California.

HSI1n. Know that when an observation does not agree with an accepted scientific theory, the observation is sometimes mistaken or fraudulent (e.g., the Piltdown Man fossil or unidentified flying objects) and that the theory is sometimes wrong (e.g., the Ptolemaic model of the movement of the Sun, Moon, and planets).

Chemistry Standards:

Conservation of Matter and Stoichiometry

HSC3. The conservation of atoms in chemical reactions leads to the principle of conservation of matter and the ability to calculate the mass of products and reactants. As a basis for understanding this concept:

HSC3a. Students know how to describe chemical reactions by writing balanced equations.

HSC3b. Students know the quantity one mole is set by defining one mole of carbon 12 atoms to have a mass of exactly 12 grams.

HSC3c. Students know one mole equals 6.02 x 1023 particles (atoms or molecules).

HSC3d. Students know how to determine the molar mass of a molecule from its chemical formula and a table of atomic masses and how to convert the mass of a molecular substance to moles, number of particles, or volume of gas at standard temperature and pressure.

Gases and Their Properties

HSC4. The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. As a basis for understanding this concept:

HSC4a. Students know the random motion of molecules and their collisions with a surface create the observable pressure on that surface.

HSC4b. Students know the random motion of molecules explains the diffusion of gases.

HSC4c. Students know how to apply the gas laws to relations between the pressure, temperature, and volume of any amount of an ideal gas or any mixture of ideal gases.

HSC4d. Students know the values and meanings of standard temperature and pressure (STP).

HSC4e. Students know how to convert between the Celsius and Kelvin temperature scales.

HSC4f. Students know there is no temperature lower than 0 Kelvin.

HSC4g.* Students know the kinetic theory of gases relates the absolute temperature of a gas to the average kinetic energy of its molecules or atoms.

HSC4h.* Students know how to solve problems by using the ideal gas law in the form PV = nRT.

HSC4i.* Students know how to apply Dalton’s law of partial pressures to describe the composition of gases and Graham’s law to predict diffusion of gases.

Objectives:

Students will demonstrate their ability to be Critical Thinkers by applying knowledge of gas properties and laws to use measurement to calculate the volume of one mole of gas at STP.

Students will demonstrate Effective Communication skills by publishing their work in the form of a detailed lab report.

Activity:

The students will use measurements of gas collected from the reaction of hydrochloric acid and magnesium metal to calculate the molar volume of a gas.

Assessment Products:

Published lab report (designed according to established NPHS Science Department guideline

Newbury Park High School - Science: Chemistry ESLR Rubric

MATRIX FOR ASSIGNMENTS OF MARKS:

3= ccc

2= ccp/ cpp

1= ppp/ cpn/ ppn/ cnn

0= pnn/ nnn

MATRIX FOR OVERALL ESLR SCORE:

3= 333/ 332

2= 322/ 222/ 221

1= 211/ 111

0= did not do

INTRODUCTION

LEVELS / COMPLETE / PARTIAL / NOT AT ALL

Defining the Problem or Research Question

/ Identifies a problem or research question / States the problem or research question, but it is unclear or incomplete. / Does not state the problem or research question
Formulating a hypothesis or prediction / Relates the hypothesis or prediction to the research question and explains it. / States the hypothesis or prediction but does not explain it. / Does not state a hypothesis or prediction.
Explaining Procedure / Describes a method that allows for the collection of sufficient relevant data. / Describes a method that allows for the collection of insufficient relevant data. / Describes a method/ or lack of method that does not allow any relevant data to be collected.

DATA COLLECTION & PRESENTATION

LEVELS / COMPLETE / PARTIAL / NOT AT ALL

Collecting & Recording Data

/ Records appropriate data (qualitative &/or quantitative), including units and uncertainties where necessary. / Records some appropriate data and has some units where necessary. / Does not record any appropriate data or units.
Organizing & Presenting Data / Presents data clearly, allowing for easy interpretation. / Presents data but does not allow for easy interpretation. / Does not present data or presents it incomprehensibly.
Performing & Presenting Calculations / Presents calculations appropriately and, where relevant, takes into account errors and uncertainties. / Presents calculations appropriately but with some errors and/or omissions. / Does not present data or presents it incomprehensibly.

CONCLUSION & EVALUATION

LEVELS / COMPLETE / PARTIAL / NOT AT ALL

Drawing Conclusions

/ Gives a valid conclusion, based on the correct interpretation of results, with an explanation and, where appropriate, compares results with textbook or teacher values. / States a conclusion that has some validity, and /or some explanation. / Draws a conclusion that misinterprets the results.
Evaluating Procedure(s) & Results / Thoroughly evaluates procedure(s) and results including weaknesses and errors. / Evaluates procedure(s) and results but misses some obvious errors. / The evaluation is weak and does not state errors beyond the superficial or irrelevant.
Makes ample suggestions for improvement to existing methods. / Identifies areas for improvement and describes realistic suggestions to improve the investigation. / Suggests only simplistic improvements. / Suggests unrealistic improvements or does not suggest any improvement at all.

ESLR Scoring Rubric

Student Name: ______

INTRODUCTION:

Task / ESLR Score
Defining the problem or research question
Formulating a hypothesis or prediction
Explaining procedure
INTRODUCTION SCORE

DATA COLLECTION & PRESENTATION:

Task / ESLR Score
Collecting and Recording Data
Organizing and Presenting Data
Performing & Presenting Calculations

COLLECTION & PRESENTATION SCORE

CONCLUSION & EVALUATION:

Task / ESLR Score
Drawing conclusions
Evaluating procedure(s) & results
Making suggestions for improvement
CONCLUSION & EVALUATION SCORE
OVERALL ESLR SCORE:

Published Laboratory Report Grading Rubric:

Molar Volume of a Gas

This report must be submitted to Ms. Stevens on or before Wednesday, May 2

Section of Laboratory Report / Comments /
Pts. subtracted / Points Possible
Title page: includes the name of the lab, names of each group member, dates of the lab, date of report, and clearly states what section(s) each group member was responsible for. / 2
Abstract: a brief (1 paragraph) summary of the purpose, general method and steps followed in doing your experiment and a summary of the overall results in general terms. / 6
Purpose: a short description of the problem being investigated or the specific question you are trying to test. / 2
Hypothesis: an educated “guess” or prediction about what your results will be like. Clearly state the basis for your hypothesis. / 2
Theory: discuss the theory of the experiment (i.e. background information such as the chemical equation for this reaction, information about gases, etc.); list any applicable equations (gas laws used, etc); give references to literature when appropriate. / 4
Setup, Materials, & Method: ( 1)An alphabetized list of equipment used and a digital diagram (photograph, Paint picture, scanned drawing, etc.) of the equipment set up. (2) A listing (with numbered steps) of the detailed procedures you followed during your experiment, including safety precautions taken. / 8
Results/Data: table(s) that are clearly labeled and include all units. Show raw data and averages. Include a description of your visual observations. / 4
Calculations: Clearly label and show work for calculations #1-7. Format that this section so that headings and answers stand out. Equation Editor works best for this; if you don’t use this application you still must type your calculations. (2 pts ea.) / 14
Discussion/Conclusions:
1)Restate purpose of this lab (1)
2)Summarize procedures (1)
3)Restate results & percentage of % error (1)
4)Explain at least three sources of error in this experiment and describe how each source of error could have affected your data (3)
5)Describe at least two ways of that you could improve these procedures to yield better results if given the chance to repeat this lab. (2) / 8
TOTAL: / 50

Molar Volume of a Gas

PRE-LAB DISCUSSION

Avogadro’s hypothesis states that equal volumes of all gases contain equal numbers of molecules under the same conditions of temperature and pressure. It follows from this hypothesis that all gas samples containing the same number of molecules will occupy the same volume under the same conditions of temperature and pressure. A special name is given to the volume occupied by 1-mole samples of gases at STP. This volume is called the molar volume. In this experiment, you will make an experimental determination of the molar volume.

The basis of this experiment is the following reaction in which you will react a known mass of magnesium with excess hydrochloric acid to produce the substances shown:

Mg(s) + 2HCl(aq)  MgCl2(aq) + H2 (g)

The hydrogen gas is the product that is of interest to you in this experiment. You will make an experimental determination of the number of moles of hydrogen molecules produced and the volume occupied by these molecules. The number of moles of hydrogen will be determined indirectly. The balanced equations for this reaction shows that the molar ratio of magnesium reacted to hydrogen gas produced is 1:1. Therefore, by determining the mass of magnesium that reacts and the number of moles that this mass is equal to, you will also be able to determine the number of moles of hydrogen gas produced. The volume of hydrogen gas produced will be measured directly on the scale of a gas-measuring tube. The gas laws of Boyle and Charles will be used to correct this volume, measured under laboratory conditions, to the volume the sample of gas would occupy at STP. The collected data (number of moles and volumes at STP) will be used to calculate that molar volume of the hydrogen gas.

This experiment should aid in the understanding of the mole concept and the concepts of molar volume of a gas.

PURPOSE

Determine the volume of 1 mole of hydrogen gas at STP using experimental data, known mathematical relationships, and a balanced chemical equation.

EQUIPMENT & MATERIALS

Gas-measuring tubeCopper wire – 15 cm (HCl) ~ 10 mL

Graduated cylinder, 10-mL Hydrochloric acid 3.0 M

Graduated cylinder, 1000-mL Magnesium ribbon (Mg) ~ 5 to 7 cm

Metric ruler Water, distilled ~ 110 mL

Rubber stopper w/ one-hole stopper

Safety glasses

Thermometer

PROCEDURE

Obtain a piece of magnesium ribbon from your teacher. Measure the length of the piece of ribbon (to the nearest 0.1 cm). Record the length as (a) in your data table. Also record the mass of 1 meter of magnesium ribbon. These data will be provided by the teacher. Record as (b).
Obtain a piece of copper wire about 15 cm long. Wrap one end of the wire around the piece of magnesium ribbon, leaving about 10 cm of thread free. Bend the piece of magnesium so that it will fit easily into the gas-measuring tube.
Obtain about 10 mL of 3 M hydrochloric acid (HCl). CAUTION: Handle this acid with care. Carefully pour the HCl into a gas-measuring tube.
Tilt the gas-measuring tube slightly. Using a beaker, slowly fill the gas-measuring tube with water at room temperature. Try to avoid mixing the acid and water as much as possible.
Lower the piece of magnesium ribbon (coiled and held in place by copper wire) 4 or 5 cm into the gas-measuring tube. Drape the wire over the edge of the tube and insert the one-hole rubber stopper into the tube as shown in Figure 1.
Add about 900 mL of water at room temperature to a 1-L graduated cylinder. Place your finger over the hole in the rubber stopper and invert the gas-measuring tube. Lower the stoppered end of the tube into the large graduated cylinder of water. Record your visual observations as (g) in the data table.
Let the apparatus stand about five minutes after the magnesium has completely reacted. Then, tap the sides of the gas-measuring tube to dislodge any gas bubbles that may have become attached to the sides of the tube.
Move the tube up or down (to equalize pressure) until the water level in the tube is the same as that in the graduated cylinder. On the scale of the gas-measuring tube, read the volume of the gases in the tube. Record this volume as (c) in your data table.
In the data table, record the room temperature (d), and the barometric pressure (e).
If time permits and your teacher so indicates, repeat the experiment. If time does not allow, then gather data from one or two other groups to average with your own.

Figure 1: Initial SetupFigure 2: Final SetupOBSERVATIONS AND DATA

Measurement / Trial 1 / Trial 2 / AVERAGE
(a) length of Mg ribbon / cm / cm / cm
(b) mass of 1 meter of Mg / g / g / g
(c) volume of H2 gas in tube / mL / mL / mL
(d) room temperature / °C / °C / °C
(e) barometric pressure / mm Hg / mm Hg / mm Hg
(f) water vapor pressure at room temperature, PH2O (from textbook appendix) / mm Hg / mm Hg / mm Hg
(g) visual observations

CALCULATIONS

Find the mass of the Mg strip:

For example:

0.070 meter =x grams

1.00 metermass of 1-meter length

Calculate the number of moles of Mg reacted (which is equal to the number of moles H2 gas produced): *Hint: use molar mass of magnesium!

# moles Mg =

Find the pressure exerted by the H2 gas in the tube:

PH2 = Pbarometric - PH2O

Convert room temperature from °C to Kelvin:

K = °C + 273

Find the volume of the H2 gas at STP:

P1V1 = P2V2 OR V2 = (V1 x P1 x T2) ,where: P1 = PH2 (from calculation 3)

T1 T2 (P2 x T1)V1 = experimental value of H2 (c)

T1 = room temperature (K)

T2 = 273 K

P2 = 760 mm Hg

V2 = volume of H2 at STP

Find the volume of 1 mole of H2 gas at STP:

Moles of H2 gas (from calculation 2) = 1 mole

Volume of H2 gas (V2) x mL

x = ______mL/mole = ______L/mole

7. Calculate your percentage error for the volume of a mole of gas at STP.

DISCUSSION & CONCLUSION

In paragraph form, follow the instructions from your lab report handout for writing/publishing your conclusion. Don’t skimp here, this is one of the most important parts of your report!