Download Study Guide for Quiz II

Study Guide for Quiz II
For each lab, review all pre-lab questions, reports and post-lab questions. Look at corrections made on your lab report
during grading. Work the sample questions below. Remember that all possible types of questions may not be
represented.
VSEPR Modeling : Most of the quiz for this lab will be filling in a table like the following:
NO3-
Molecular Formula
Number of Valence eLewis Dot Structure
Molecular Type (i.e.
AB2E2)
Electron Pair Geometry
(name and sketch)
Molecular Geometry
(name and sketch)
Gas Laws
1. Review the details for performing the Boyle’s Law and Charles’ Law experiments and be able to answer questions
about the experimental procedure for them. For example, how was pressure on the gas increased in the Boyle’s Law
experiment?
2. Know the equations for Charles’ and Boyle’s law and be able to use them by working a problem.
3. Given data from a Boyle’s law experiment like you performed in lab, be able to calculate a V2 as you did in Boyle’s
Law post- lab question 2. Then be able to calculate a % error for the experimental V2 as you did in Boyle’s Law postlab question 3.
Example for first part: Complete the blanks in the following table.
Trial
1
Mass Added
(kg)
0.5
Volume (mL)
Pressure (total mass, kg)
25.9
5.0
PxV
1.5
22.7
6.0
Calculate the theoretical volume for a weight of 1.5 kg on the plunger using Boyle’s Law formula
the data from Trial one. Show calculations!
V2 = _____________
2
4. In a similar manner, be able to calculate a theoretical V2 for a Charles Law experiment given appropriate
experimental data. Then, be able to calculate the % error of the experimental V2.
5. Be able to answer questions from the Charles’ Law post lab.
Example: What happened to the speed of the molecules when the air in the flask was heated?
and
Chemistry of Copper Lab
In general: Be able to identify the type of reaction, predict products, write correct formulas, and balance equations.
Know the colors of all the copper containing products.
Review the experiment and your results. Make sure you understand each step that you performed. For example, why
was reaction 1 performed in the hood?
1. Classify the type of reaction and balance the equation: Cu + O2 → CuO
2. Classify the reaction, predict the products, balance the equation and write the net ionic equation for
Cu (s) + AgNO3 (aq) →
3. Calculate the percent yield if you started with 1.56 g of copper wire and recovered 0.88 g of copper.
4. What was the color of CuO?
Representing Chemical Structures
Be able to write expanded structures from line structures and vice versa. (p. 8 in lab)
1. Are the following compounds isomers, the same compound or neither? (Two compounds are isomers if they have
the same molecular formula, but different structure.)
H
C
H
H
H
C
H
H
C
C
H
H
H
C
H
H
C
C
H
H
H
H
H
H
C
H
H
H
2. Draw a flat picture of a six carbon alkane with the longest possible chain of carbon atoms. Indicate the name and
formula. Then rearrange the carbon chain to form an isomer.
longest chain
isomer
# of C in
main chain
2
3
4
5
6
7
name:
name
ethane
propane
butane
pentane
hexane
heptane
formula: ________________
3. Draw a perspective line drawing and Haworth projection for cis-1,2-dichlorocyclopentane (question 3, postlab).
4. Draw flat structures for two isomers of dibromopropane (C3H6Br2) and name them.
5. What is necessary for a carbon to be chiral?
Some Answers
VSEPR
For: NO3- 24 valence electron.
In the dot structure, there are single bonds between two of the oxygens and nitrogen. There is a double bond
between the last O and the N. N has no non-bonding electron pairs. The dot structure is bracketed with a negative
charge on the outside.
The molecular type is AB3.
The electron pair geometry is trigonal planar. (Need drawing as well.)
The molecular shape is trigonal planar. (Need drawing as well.)
Gas Laws
1. The pressure on the gas was increased by adding weights on top of the syringe.
2. Charles’ Law, V1 / T1 = V2 / T2
Boyle’s law, P1V1 = P2V2
3. Example: Complete the blanks in the following table.
Trial
Mass Added
(kg)
0.5
1
Volume (mL)
Pressure (total mass, kg)
PxV
25.9
5.0
(129.5) 130 kg . mL
1.5
22.4
6.0
(134.4) 130 kg . mL
Calculate the theoretical volume, V2, for trial 2 using Boyle’s Law formula and the data from Trial one.
(You must show work.) V2 = (21.58) or 22 mL
2
5. The speed of the molecules increased when the air in the flask was heated.
Chemistry of Copper Lab
1. Classify the type of reaction and balance the equation:
2 Cu + O2 → 2 CuO
Combination or synthesis
2. Classify the reaction, predict the products, balance the equation and write the net ionic equation for
Single replacement
Cu (s) + 2 AgNO3 (aq) → 2 Ag + Cu(NO3)2
(This reaction proceeds because copper is more active than silver.)
NIE
Cu (s) + 2 Ag+ (aq) → 2 Ag + Cu2+
3. Calculate the percent yield if you started with 1.56 g of copper wire and recovered 0.88 g of copper.
x 100% = 56.4% rounds to 56%
Representing Chemical Structures
1. Are the following compounds isomers, the same compound or neither? (Two compounds are isomers if they have the same
molecular formula, but different structure.)
H
C
C
C
H
H
H
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
H
C
H
H
H
These are isomers. They have the same number of each type of atom. But they are connected in different ways
to give different structures.
2. Draw a flat picture of a six carbon alkane with the longest possible chain of carbon atoms. Indicate the name and formula.
Then rearrange the carbon chain to form an isomer.
H
H
H H
H H
H
C
C C
C C
C
H
H H
H H
H
H
longest chain
isomer
name: hexane
formula: C6H14
3. Draw a perspective line drawing and Haworth projection for cis-1,2-dichlorocyclopentane (question 1, postlab).
Cl
Cl
Cl
Cl
4. Draw flat structures for two isomers of dibromopropane (C3H6Br2) and name them.
H H Br
H C C C Br
H H H
1,2-dibromopropane
1,1-dibromopropane
(How many more isomers are there?)