EXAM 1 SUMMARY SESSION
CHEM 111
Sunday, September 24, 2023
Liz Cao, Amanda Duban, and Eric Zheng
drewcrew111@case.edu
(Please note, we will NOT be answering emails after
11 PM the night before your exam.)
Exam Date: September 27, 2023
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Topics to Cover:
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Significant Figures and Precision vs Accuracy
Experiments - Rutherford Gold Foil and Millikan Oil Drop
Atomic Model and Isotopes
Naming (ionic and covalent compounds, polyatomic ions, acids)
Mass spectrometry
Empirical and Molecular Formula/Percent Yield
Combustion Analysis
Balancing Chemical Equations
Gravimetric Analysis
Stoichiometry and Limiting Reagents
Solutions and Dilutions with Terminology
Types of Reactions
Disclaimer: This is not a complete list of topics you need to know for your exam, but rather
is a list of high-yield topics we will be covering in the summary session. For the complete
list of topics to know, please look at the learning objectives posted on Canvas and included
in PPT presentations.
Sig Figs:
What is the purpose of sig figs?
Know your sig fig rules: trailing zeros, leading zeros, captive zeros, exact numbers,
operations with addition, subtraction, multiplication, and division.
Terms:
___________: how close together different measurements are
___________: how close the measurements are to the actual result
After making their hit music in the 90’s, NSYNC decided to shift their focus to a life of
chemistry. Which NSYNC member was precise but not accurate while measuring the molar mass
of glucose (180.16 g/mol)? Accurate but not precise? Both precise and accurate?
Justin Timberlake
Joey Fatone
Chris Kirkpatrick
JC Chasez
183.21
180.17
178.00
181.21
183.20
180.16
182.01
185.76
183.21
180.17
182.10
176.54
182.99
180.16
178.15
186.23
Atomic History:
1. The ______________ oil drop experiment helped discover the __________ on a(n)
______________.
a. What was the basic protocol that was used?
2. The _____________ gold foil experiment helped discover the existence of the
____________.
a. What was the basic protocol that was used?
Naming:
Ionic Compound Naming:
1) ____________ named first and __________ named second.
2) Cation takes the name of the ____________________________.
3) Anion is named by taking the root of the element and adding _____ to the end.
4) No _____________.
5) Roman numerals are used to indicate the ___________ of ______________________.
Covalent Compound Naming:
1) Formed between two ____________.
2) More _________ named first, using the full element name.
3) Second element has the suffix -__________.
4) ____________ are used to denote the number of atoms present.
Acid Naming:
● Acids without oxygen
○ HYDRO ____________ IC ACID
● Acids with oxygen
○
Anion Ends In
Acid Suffix
-ATE
-ITE
Name the compound and star ionic compounds, circle covalent compounds, and box acids.
FeO(s):
HNO2 (aq)
HBr(s):
N2O5 (g):
H2SO4 (aq):
CuCl2 (g):
CoCO3 (s)
Li2S (s)
Write the chemical symbol for each compound.
Potassium sulfide:
Chromium (III) bromide:
Dihydrogen monoxide:
Hydrofluoric acid:
Tin (IV) phosphate:
Tetraphosphorus heptasulfide:
Mass Spectrometry:
Chlorine has two stable isotopes: Cl35 and Cl37. Assuming both are equally abundant, complete
the mass spectrometry diagram below for a diatomic chlorine gas molecule.
Empirical and Molecular Formulas:
1. Nicotine is mainly responsible for the addictive nature of cigarettes. A typical cigarette
contains 12.33mg C, 1.45mg H, and 2.87mg N. What is the empirical formula of
nicotine?
a. If the molar mass of nicotine is 162 g/mol, what is the molecular formula of
nicotine?
2. Determine the molecular formula of a compound that contains 26.6% P, 12.1%N, and
61.2% Cl and has a molar mass of 580g/mol
Combustion Analysis:
1) A 0.1034 g sample of a compound composed of carbon, hydrogen and oxygen is
subjected to combustion analysis, producing 0.2351g CO2 and 0.0962 g H2O. What is the
empirical formula for the compound?
2) The combustion of 40.10 g of a compound which contains only C, H, Cl and O yields
58.57 g of CO2 and 14.98 g of H2O. Another sample of the compound with a mass of
75.00 g is found to contain 22.06 g of Cl. What is the empirical formula of the
compound?
Balancing Chemical Equations:
Tips for Balancing Chemical Equations:
1) If an element is present in just one compound on each side, balance it first / last
2) Balance anything that exists as a free element first / last
3) Balance polyatomic ions as a ________
4) Check when done- same number of _________ and same ________ _________ (if any)
on both sides
Let’s balance some equations!
1) _____ C + ______ SO2 → _____ CS2 + ______ CO
2) _____ Rb + ______ S8 → _____ Rb2S
3) ____ Al(OH)3 + _____ H2CO3 → ____ Al2(CO3)3 + ____ H2O
4) ____ H3PO4 + _____ Mg(OH)2 → _____ Mg3(PO4)2 + ____ H2O
5) ____ K + ____ B2O3 → ____ K2O + ____ B
Stoichiometry and Limiting Reagents:
1. If 4.95g of ethylene (C2H4) are combusted with 3.25g of oxygen, how many grams of
CO2 will be produced. Hint: start with a ______________ chemical equation.
2. Take the following reaction: NH3 + O2 → NO + H2O. If 3.25 g NH3 is allowed to react
with 3.50g O2 , how many grams of NO can be formed and what is the limiting reagent.
a. How much of the excess reagent remains after the reaction is complete
3. Silicon nitride (Si3N4) is made by combining Si and nitrogen gas (N2) at high
temperature. How much (in g) Si is needed to react with an excess of nitrogen gas to
prepare 125g of silicon nitride if the percent yield of the reaction is 95.0%?
4. One commercial system removes SO2 emissions from smoke at 95.0℃ by the following
set of balanced reactions:
SO2(g) + Cl2(g) → SO2CL2(g)
SO2Cl2(g) + 2H2O(l) → H2SO4(aq) + 2HCl(g)
H2SO4(aq) + Ca(OH)2(s) → CaSO4(s) + 2H2O(l)
Assuming the process is 95.0% efficient, how many grams of CaSO4 may be produced
from 100. Grams of SO2 and 75.0 g of Cl2?
Gravimetric Analysis:
The formula of an acid is only partially known as HXO3. The mass of 8.13x1020 molecules of the
acid is 0.085 grams. Find the atomic mass and identity of X.
Hint: for CHEM 111, we can always identify substances based on their:___________
Solutions:
1. A 200 g sample of sodium phosphate is dissolved in enough water to make 1.50 L, what
is the molarity of the solution?
2. What is the universal equation we use to solve dilution problems?
3. If 45 mL of water are added to 250 mL of a 0.75 M K2SO4 solution, what will the
molarity of the diluted solution be?
Types of Reactions:
Label which of the three types of reactions the image represents and write a brief definition for
each.
Study Tips:
● Look through and make sure that you can answer/explain every learning objective posted
on Canvas by Dr. Meyer
● Complete online practice problems located on Canvas
● Review discussion section worksheets and active learnings
● The textbook has great practice problems and clear explanations of many topics
● Look through previous SI sheets
● Make flashcards, Quizlets, etc. to memorize polyatomic ions
● Email the SIs with any questions (we will NOT be answering emails after 11 PM at
night)
● Form study groups and work together -- if you can teach something to someone else, you
probably know it well! Consider attending the community leader sessions as well!
● VERY IMPORTANT
○ Sleep and eat well before your exam! You can only perform at the level your SIs
know you can if you take care of yourself! You got this! We believe in you!!!
Good luck, your SIs are rooting for you! :)
Disclaimer: please stay hydrated while studying y’all!! You’ve got this! :)