CH 115 ACS Exam 4 Sunday Review

Exam Overview

  • Covering chapters: 1-13, 15.2, and 15.3.

  • Room assignments posted on Canvas; likely unchanged.

  • Arrive 10 minutes early to settle in.

  • Exam will be collected at 5:55 PM regardless of arrival time.

  • Limited time allotted for the exam, with specific accommodations for extra time.

  • No cover pages or cheat sheets allowed. Only acceptable materials: working calculator and pencil.

  • Students will receive a booklet with:

    • A cover page containing formulas.

    • A Scantron for answers.

  • Ensure knowledge of student ID for Scantron.

  • All personal items, including phones, must remain in bags.

Study Tips

  • Utilize self-assessment quizzes, exam keys, worksheets, and answer keys available online.

  • Practice exam recommended for preparation.

  • Completing the Mastering Chemistry Conceptual Review can earn 10 points of extra credit.

  • Use the provided cover sheet for calculations and note steps taken in problem-solving.

  • With a 55-minute time limit, answer questions you are sure of first.

Concepts Covered in Review

  • Avogadro's Number:

    • Equals one mole of particles (atoms, molecules, etc.).

  • Covalent Bonds:

    • Occur between nonmetals; bromine will covalently bond with nitrogen.

    • Compounds with two nonmetals exist as molecules due to the formation of covalent bonds.

  • Naming Compounds:

    • Example: Mg₃(PO₄)₂ = Magnesium Phosphate.

    • Review all naming rules for ionic and covalent compounds.

  • Diatomic Elements:

    • Key to remembering; exist naturally as pairs except neon and calcium.

Problem-Solving Strategies

  • Stoichiometry:

    • Convert grams to moles to determine the moles of other substances using molar ratios from balanced reactions.

  • To find mass of bromine trifluoride with the same number of fluorine atoms as 25g of oxygen difluoride, convert 25g to moles and utilize the mole-to-mole ratio between compounds.

  • Mass Comparison:

    • Convert moles of various options to grams to identify the smallest mass.

    • Example: 0.01 kg of Br₂ = 10g.

  • Ionic Compounds and Mole Ratios:

    • Calcium perchlorate gives a total of 3 ions; find the option with the same summation.

  • Empirical Formulas:

    • Represent simplest whole-number ratio. C₆H₁₂O₆ is not an empirical formula.

Key Reactions and Concepts

  • Combination Reactions:

    • Rubidium and nitrogen react to produce rubidium nitride; apply the balanced equation to find moles needed.

  • Dilution Problems:

    • Use M₁V₁ = M₂V₂ for calculating volume required for dilutions.

  • Redox Reactions:

    • Reduction involves gaining electrons and lowering oxidation state; oxidation and reduction always occur together.

  • Net Ionic Equations:

    • Write balanced and full ionic equations, cancel out spectator ions to find net ionic.

Final Questions and Clarifications

  • Students should be prepared for questions on calculating concentrations, stoichiometry, and identifying ions in reactions.

  • Review mechanisms for determining limiting reactants and excess reactants in chemical reactions.