Name: ______________________________________________________ Date: _____________ Teacher: J. Richardson

AP Chemistry: Week 6 Assignments 5/11 to 5/17

Do you have access to technology? Did you get this off of my website?

If so, this is not the assignment for you! This packet is only for students who have little to

no access to technology. Please go to the AP chemistry assignment page instead:

https://ca01001129.schoolwires.net/Page/17496

Scroll down to “current assignments”, then click “week 6”. That is your assignment!

The AP exam is THIS WEEK! Wooooo!

This week I really want all of you to focus on studying for the exam. However, I know many of you also have multiple exams you are taking this week. That is why most of this week's assignments are optional, though they are encouraged as they are meant to help you prepare for the exam.

Part 1: AP Exam Prep Checklist--mandatory for everyone taking the exam, finish by Wednesday!

1. Read through and fill out the AP Exam Prep Checklist (pages 2-3) to help you prepare for the AP exam. Have it ready with you when you are taking the AP exam as a reference. If you are not taking the AP exam, you do not need to do this.

Part 2: Practice Exam (optional but recommended)

1. The college board has released a practice exam that is similar in length and difficulty to the actual AP exam. Here is what I recommend you do:

1. Get your cheat sheet, reference sheets, calculator, and a timer ready 2. Complete the practice exam exactly like you plan on doing the real one--whether that means typed or handwritten

1. give yourself 25 minutes for the first question, then give yourself 5 minutes to take pictures/get your document ready

2. give yourself 15 minutes for the second question, then give yourself 5 minutes to take pictures/get your document ready

3. Email your answers to me--if you do I will give you feedback on whether or not the format is acceptable, then send you an answer key to check your work

2. The practice exam is on pages 4-5.

Part 3: Peer Review Cheat Sheets (optional but recommended)

1. In turnitin.com there is a "peer review" assignment for the cheat sheets. It opens Sunday (after everyone submits their cheat sheets). Go in and review your peer's cheat sheets--use this to get ideas of what to add to your own! This isn't graded, its just an opportunity to help you out.

Let's Go AP Chem! We got this!

2020 AP Exam Day ChecklistDirections: Complete this checklist for each AP® Exam you take this year. Go to cb.org/ap2020 for the AP Testing Guide, videos, and other resources.

¨ Write your 8-character AP ID

§ You can find this in your exam confirmation email, your exam e-ticket email, or on My AP (myap.collegeboard.org).

¨ Write the name of your exam

¨ Write the exam date, local check-in time, and local start time

§ Check the exam calendar: Exams start at your local equivalent of 12 p.m., 2 p.m., or 4 p.m., Eastern Daylight Time. You must calculate the start time for YOUR time zone.

§ You must click your e-ticket to check in and complete security checks 30 minutes before your local exam start time.

Exam date: _______________________________

My local exam check-in time: _______________

My local exam start time: __________________

Please note: if you’re taking a world language exam, checklist items about handwriting or typing responses, attaching and submitting responses, and the exam timer don’t apply. If you’re taking a Music Theory exam, checklist items about typed responses don’t apply.

Am I Ready to Test? ¨ I have my AP Exam e-ticket email for this subject or have

access to my e-ticket on My AP (myap.collegeboard.org). I have checked that the ticket is for this exam, not for another AP Exam I’m taking, and has today’s exam date on it.

¨ My device is plugged in.

¨ When I click on a link, the browser that opens is Chrome™, Firefox®, Safari, or Edge. The exam will not open in other browsers, so I have confirmed my default browser is one of these four browsers, which support online AP Exams.

¨ I have practiced with the exam demo at cb.org/apdemo, which confirms that my device and browser will be able to access the exam.

¨ If I will be typing my exam, I have opened a Google Doc, a Word doc, or another type of document I will type my response into. I have prepared one document for English and history exams and two for other subjects. I have typed my 8-character AP ID and my initials at the top of each document.

¨ If I will be handwriting my exam, I have prepared one set of pages for English and history exams and two sets of pages for other subjects. I have written my 8-character AP ID, my initials, and the page number at the top of each page.

¨ I have reviewed the list of required materials for this specific exam at cb.org/apexamdaydocs and printed or downloaded a copy of any required documents.

¨ I have reviewed the exam security guidelines and understand the consequences for incorporating work that is not my own or collaborating with anyone during the exam.

¨ If I’ve been approved by the College Board to test with accommodations, I’ve reviewed the information at cb.org/ap2020accommodations and have any needed assistive technology and devices.

¨ If I’m taking the AP Music Theory Exam:

¨ I have a recording app or recording software (such as Voice Memos, GarageBand®, Recorder, Audacity®, etc.) on my device and know how to use it.

¨ I have 2–3 paper copies of the AP Music Theory answer sheet template.

¨ If I’m taking a world language and culture exam:

¨ I downloaded the AP World Languages Exam App from the Apple® App Store (to an iPhone® or iPad®) or from the Google Play Store™ (to an Android™ device), practiced with the app, and gave the app permission to use the microphone.

¨ I confirmed that my device can access the internet by Wi-Fi or cellular data, has at least 30MB of available storage, and is charged to at least 25% battery power or is plugged in.

¨ I’m in a location with no or limited background noise where my voice can be recorded clearly.

¨ I have closed the AP World Languages Exam App on my device before the start of the exam.

During the Exam ¨ Once the exam has started, I won’t refresh the browser

or use the back arrow.

¨ I will keep the exam question open on my device so I can see the timer and 5-minute warning.

¨ When I see the onscreen warning that time is almost up (5 minutes before the deadline for submitting my response), I will STOP working on my response and start the process for attaching/pasting and submitting it.

¨ I understand that if I do not attach or paste my response and click Submit before the countdown on my screen is complete, I will receive 0 points for that question.

¨ If I accidentally close my browser or tab, temporarily lose my internet connection, or experience some other disruption, I will click my e-ticket to rejoin my exam.

¨ If I can’t rejoin my exam, lose too much time trying to regain access, or do not see a Your AP Exam is Complete message at the end of the exam, I can request a makeup test by completing the form at cb.org/requestmakeup.

¨ If I’m taking a world language and culture exam:

¨ I will start my exam from my e-ticket on the device that has the AP World Languages Exam App installed.

¨ I will not open the app directly. When prompted, I will select Start My Exam to launch the app. This is the only way to start the exam.

¨ Once I’ve launched the app by selecting Start My Exam, I will complete my exam using the app.

After the Exam ¨ I will sign in to My AP and indicate the college, university,

or scholarship program that should receive my free score report. Deadline: June 20, 2020.

¨ I will report information about cheating attempts at: collegeboard.org/reportcheating.

© 2020 College Board. 01840-061

2020 Exam Sample QuestionsAP® CHEMISTRY

Sample Question 1Time allotted: 25 minutes (plus 5 minutes to submit)Common additives to drinking water include elemental chlorine, chloride ions, and phosphate ions. Recently, reports of elevated lead levels in drinking water have

been reported in cities with pipes that contain lead, Pb(s). When Cl2(aq) flows

through a metal pipe containing Pb(s), some of the lead atoms oxidize, losing two electrons each, and aqueous chloride ions form.

(a) Write a balanced, net-ionic equation for the reaction between Pb(s) , and

Cl2(aq) .

Dissolution reactions and Ksp values for two lead compounds are given in the following table.

Dissolution Reaction Ksp

PbCl2(s) ! Pb2+ (aq) + 2 Cl− (aq) 1.6 × 10−5

Pb3(PO4)2(s) ! 3 Pb2+ (aq) + 2 PO43− (aq) 1.08 × 10−53

(b) Write the Ksp expression for the dissolution of Pb3(PO4)2(s) in water.

(c) Calculate the molar solubility of Pb3(PO4)2(s) .

(d) Using the table of Ksp values above, explain why the addition of

PO43− (aq) is more effective at reducing [Pb2+ ] in drinking water than

Cl− (aq) .(e) Cities try to maintain a maximum dissolved lead concentration of

[Pb2+ ] = 1.0 × 10−9M . If a sample of water has [Pb2+ ] = 1.0 × 10−9M

and enough phosphate is added such that [PO43− ] = 3.0 × 10−5M , would

the concentration of Pb2+ (aq) increase, decrease, or remain the same?

Justify your answer with a comparison of Q and Ksp .

(f) Higher concentrations of Pb2+ (aq) are found in pipes carrying hot water than in pipes carrying cold water. Is this observation consistent with a

negative enthalpy of dissolution, ΔHsoln ? Justify your answer with regards to LeChâtelier’s principle.

AP Chemistry 2020 Exam | Sample Questions 2

A student researches the properties of the phosphate ion and finds the following Lewis electron-dot diagrams and table of bond lengths:

Diagram 1 Diagram 2

Bond type Bond length (pm)P−O 163P=O 150

(g) Using diagram 1, the student claims that the bond angles are 90°. Do you agree or disagree with the student’s claim? Justify your answer in terms of VSEPR theory.

(h) The student also finds that all four P—O bonds in phosphate have a bond length of 162.5 pm. Which diagram is consistent with this finding? Justify your answer.

(i) The student generates the following particulate diagram of an aqueous solution containing phosphate ions. The student uses dashed lines to show hydrogen bonding and omits lone pairs of electrons for clarity. Identify the letter corresponding to an incorrect hydrogen bonding interaction in the student’s diagram, and indicate how the diagram should be changed to be correct.

AP Chemistry 2020 Exam | Sample Questions 3

The complete photoelectron spectra of phosphorus and of oxygen are given in the following diagrams.

(j) The student notices that the rightmost peak of O is taller than the rightmost peak of P. The student claims that this is because O has fewer occupied electron shells, which means that the valence electrons are closer to the nucleus and experience greater attraction. Do you agree or disagree with the student’s claim? Justify your answer based on the data and principles of atomic structure.

AP Chemistry 2020 Exam | Sample Questions 4

Sample Question 2Time allotted: 15 minutes (plus 5 minutes to submit)

Methanoic acid, HCOOH(aq) , is a monoprotic acid that can be synthesized by the

reaction between CO and NH3 in the presence of hydronium ions. A proposed mechanism for the reaction consists of the three elementary steps shown below.

Step 1: CH3OH + CO → HCO2CH3 slow Step 2: HCO2CH3 + NH3 → HCONH2 + CH3OH fast

Step 3: HCONH2 + H3O+ → HCOOH + NH4

+ fast

Overall reaction: CO + NH3 + H3O+ → HCOOH + NH4

+ ΔHrxn = −81 kJ/molrxn

(a) Write the chemical formula of a species that behaves as a catalyst in themechanism.

(b) According to the proposed mechanism, if additional NH3 is added to thereaction mixture, will the rate of the overall reaction increase, decrease, orremain the same? Justify your answer.

A student generates the following potential energy diagram for the overall reaction.

(c) Is the student’s diagram consistent with the enthalpy of the overallreaction? Justify your answer.

AP Chemistry 2020 Exam | Sample Questions 5

At the end of the reaction, HCOOH is separated from CH3OH by distillation.

The chemical structures and vapor pressures at 50°C for the two substances are given below.

Substance HCOOH CH3OH

Structure

Vapor Pressure at 50°C 17.3 kPa 55.6 kPa

(d) Identify the types of intermolecular forces in HCOOH and CH3OH .

(e) When an equimolar mixture of the two compounds is heated to 50°C in the distillation, the vapor phase contains a higher mole fraction of

CH3OH molecules. Explain this result in terms of the types and relative strengths of intermolecular forces in both substances.

HCOOH(aq) + NaOH(aq) → NaHCOO(aq) + H2O(l)

The student uses NaOH(aq) to titrate a methanoic acid solution of unknown concentration. A balanced chemical equation for the reaction appears above. The student places 20.00 mL of the HCOOH solution into a flask and uses a

buret filled with 0.300 M NaOH to deliver just enough NaOH(aq) to reach the endpoint. The incomplete data from the student’s three trials are summarized in the following table.

TrialVolume of HCOOH

Initial Buret Reading

Final Buret Reading

Volume of NaOH Dispensed

1 20.00 mL 10.94 mL 27.61 mL 16.67 mL

2 20.00 mL 27.61 mL 48.84 mL ?

3 20.00 mL 1.12 mL ? ?

(f) Calculate the molarity of HCOOH from the student’s data for Trial 1.

AP Chemistry 2020 Exam | Sample Questions 6

(g) The final buret reading for Trial 3 is shown in the experimental setup below. What should the student report as the volume of NaOH(aq) dispensed for Trial 3 in the data table? Clearly show the final reading from the buret and the calculation of the volume dispensed.

(h) The student calculates a value of [HCOOH(aq)] for Trial 2 that is significantly higher than the value for the other two trials. The student claims that the reason for the higher calculated concentration is that water

remained in the flask to which the HCOOH(aq) was added, which meant

more NaOH(aq) was needed to reach the endpoint. Do you agree or disagree with the student’s claim? Justify your answer.

AP Chemistry 2020 Exam | Sample Questions 7