Blog: CHEM 1305

General Comments

1. Some of the information covered on Exam 1 might best be considered of the general science sort, and some is purely chemistry in nature. Topics covered on Exam 1 include:
   • measurements — esp. significant figures
   • dimensional anaysis • classifications of matter
   • elements, atoms, and ions
   • the mathematical relationships among protons, neutrons, electrons, and charge
   
2. View, learn, and understand all information in the instructional videos (each of the three topics are covered in detail) provided in the Exam 1 playlist.

General Comments

1. The exam covers, for the most part, three topics:
   • nomenclature
   • balancing chemical equations
   • types of reactions
   
2. View, learn, and understand all information in the instructional videos (each of the three topics are covered in detail) provided in the Exam 2 playlist.

Balancing Chemical Equations

1. See guidance provided in the BCE (Balancing Chemical Equations) blog.

Exam Tripwires

1. Multiple Reaction Type Classifications for Given Reaction: When classifying a given reaction, know that it will most likely fall into more than one class.
   — For example, a double displacement reaction in which a precipitate forms falls into at least three categories: ① ionic, ② double displacement, and ③ precipitation. A multiple choice question might have one, two, or three of these as choices.
2. Memory Items Failure: test taker failed to memorize the following:
   — 5 always-soluble ions   (Na⁺, K⁺, NH₄⁺, NO₃^–, CH₃CO₂^– or C₄H₃O₂^– )
   — 7 strong acids   (HI, HBr, HCl, HClO₃, HClO₄, H₂SO₄, HNO₃)
   — 8 strong bases   (LiOH, NaOH, KOH, RbOH, CsOH, Ba(OH)₂, Sr(OH)₂, Ca(OH)₂ )
   — 7 nomenclature ic-acids   (acetic acid, carbonic acid, nitric acid, sulfuric acid, phosphoric acid, chloric acid, chromic acid)
   — 2 exceptional ions   (hydroxide, HO^– or OH^–; ammonium NH₄⁺)
3. Mis-application of Concepts:
   — Applying Ionic reaction concepts to REDOX reactions; and applying REDOX concepts to Ionic reactions.
   — Applying the wrong nomenclature rule to a type of compound. For example, naming a Type II compound using the Type III rule.

General Comments

1. The exam covers, for the most part, three topics:
   • Stoichiometry
   • Chemical composition
   • Molarity
   
2. View, learn, and understand all information in the instructional videos (each of the three topics are covered in detail) provided in the Exam 3 playlist.

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TOPIC: Sig Figs

Hello Professor Stephenson,
I understand significant figures however I do have one quick question. When I am answering any type of number problem throughout the semester, do I need to always apply the significant figures rules? For example, if I am solving a temperature problem, do I need to make sure my answer lines up with the significant figures within the problem?

In the lab, yes. Definitely — a key component of "science" of properly recording data and calculations to the correctly level of significance.
In the lecture, most of what you will come across are multiple choice questions, and in that case — unless it's specifically a significant figure question — the answer choices are usually so far apart that whether the sig figs are reported to the first, second, or third decimal place is irrelevant. For example, if the answer choices are (a) 51 or (b) 22, it doesn't really matter whether you calculate '51.1' or '50.98... the best answer choice is clearly choice (a) and not (b).
But again, for lab work, or fill-in-the-blank, the sig figs need to be "spot-on" correct.

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