BCH 341 - Fall 2017

Prof. Marcia Levitus


Online homework will be assigned through the MasteringChemistry system. Check the Mastering Chemistry section of this website for information about how to register and tips using the site.

There will be 10 HW assignments throughout the semester. Each HW assignment in Mastering Chemistry is worth 30 pts, 5 of which are extra credit points. Therefore, you will see that the assignment is worth 30 pts, but remember that this is on a 25 point-scale as 5 of these points are extra credit. In other words, if you get all 30 points, you will have received 20% extra credit in that assignment! Take advantage of these opportunities, as it is not rare that students struggle with one or more exams due to stress. Therefore, you will compensate a not-so-great exam score with extra credit points accumulated in Mastering Chemistry during the semester.

Our view is that working on homework problems is one of the most efficient ways of learning the material. For this reason, we want students to take it as a learning experience. Getting answers right without understanding what you do will get you some points, but will not help you at all when you face a related but different problem in an exam. We encourage you to work with a small group of classmates, but keep in mind that at the end of the day, you need are responsible for your own education and you need to be sincere with yourself regarding whether you truly understood a problem you solved with friends.

The default grading policy for homework assignments is:

  • 3 attempts per question (except multiple choice questions)
  • 10% deduction for opening a hint (whenever available)
  • 5% deduction per day late of any part completed after the deadline, but never more than 50% deduction total*
  • No points for answering questions in hints (wrong or right)

* This means that you can continue to earn a significant amount of points after the deadline. For example, you will get 100% of the points of anything you submitted before the deadline, 95% of the points of the correct work you submit the next day, and 65% of the points of the correct work you submit a week after. You will even get 50% of the work you submit at any time, even the day before the last day of classes. No points will be counted for work submitted after the last day of classes at midnight.

Assignments are available for practice after you submit your answers.

Tips and issues using Mastering Chemistry

  • Avoid rounding errors. Mastering uses a default 5% acceptable rounding error in most problems (this value may vary depending on the problem). If you perform several steps and round in each, chances are you will have more than a 5% error at the end even if your procedure was correct.
  • Don't use commas for large numbers. Mastering will think you input two or more answers separated by a comma.
  • If units are required with your answer, be sure you check http://help.pearsoncmg.com/mastering/student/ccng/TopicsStudent/acceptable_units_list.htm for a complete list of accepted units and instructions of how to enter them
  • There are obvious disadvantages when a computer grades your homework. You cannot get partial credit, and you cannot get credit for mistakes that are not real mistakes (such as typing joules with a lowercase J). Don't ask us to modify your grade manually. Remember that you have 3 trials/question, so take your time to think about why your answer may be wrong before trying again. Even if you exhaust your three attempts and your answer was indeed correct (e.g. you kept using 'j' for 'J'), remember that missing one problem one time will decrease your grade by a negligible amount.
  • A disadvantage of Mastering Chemistry is that you are not practicing showing your work. You may even have a 'correct' answer that may be incorrect. For example, you may be off by 2% due to a conceptual mistake, but your work is incorrect. You will get your points in Mastering Chemistry, but you will not get the points in an exam when a human grades your work. There is no solution for this other than you taking the initiative to check your work with classmates and TAs. This is especially true when you see that your answer is off by more than 1% even if you didn't round in intermediate steps.
  • It is a good idea that you keep a notebook for homework. Many students solve problems on scratch paper, and then realize they do not have their work to study for an exam. It is not uncommon that students come to office hours asking for help, but they do not have any record of their work. Remember that your goal is not just to enter correct answers, but also to learn how to work through the problem showing all your steps.


  • Will you post the solutions?
  • We will not post the solutions to encourage you to solve all problems. You can access the assignments and solve the problems after the deadline and still get up to 50% of the points. If you are unsure of how to solve a problem even after trying and exhausting all Mastering Chemistry resources you should contact the professor or TAs for help.

  • Will you drop the lowest scores?
  • No, HW assignments allow you to earn points towards your final grade. The more you solve the more points you will get. If you don't do well in an assignment you should try to get as many extra credit points as possible in other assignments. If you miss a deadline you can always get up to 50% of the points at a later day.

  • Can I work with a classmate?
  • We obviously cannot control what you do outside the classroom. Study groups are great as long as you don't fool yourself into believing you understand something that was mostly done by another member of the group. Always be sure you can do all the work on your own!

  • Sometimes I get a correct answer but I still don't understand what I do, or why I do it. Should I worry?
  • Yes, because you will need to show your work in the exams and if you cannot justify your steps you may not get full credit. Always check with the instructor or the TAs. to be sure you know what you are doing.

  • I missed a deadline due to illness. Can I make it up?
  • No. If you miss a deadline for any reason you can always get up to 50% of the points at a later day.


Challenges are optional additional HW problems problems that will be deployed through Mastering Chemistry as the regular homework. These problems, which are more difficult than the 'regular' problems, will be assigned throughout the semester and will add up to a total of 50 possible extra credit points. The grading policy for these problems is the same as the regular homework.

These problems are meant to challenge those of you who are doing well and want to try something more difficult. You may need to do extra reading or use a little more math than usual. You should tackle these only after finishing with the regular homework. You can ask questions about these problems in office hours, but only if the instructor or the TA are not busy helping students who have other questions. In other words, you are expected to tackle these challenges mostly on your own.