Chemistry

CHF02 FOUNDATION CHEMISTRY A
ASSIGNMENT – SEMESTER 1, 2020
Total raw marks – 100 marks
% towards Continuous Assessment: 30.0%
Due Date: Thursday 4th June, 2020 (Week 14)
INSTRUCTIONS TO STUDENTS
1. Please write your answers to the assignment questions neatly on A4 blank sheets or ruled
foolscap pages. Anything that is not readable or legible will be marked wrong.
2. Answer ALL questions in blue or black ink.
3. Show all necessary working where applicable. Marks will be allocated on the basis of logical
working. In problem-solving questions, write the formula (where applicable) and show all
calculations clearly to obtain maximum marks. Ensure you answer to theory and explanation
questions are in your own words.
4. Ensure that your Full Name and ID number are on the first page, as well as, on all the other
pages of your written assignment.
5. You are required to submit both a soft copy (scanned copy) and hard copy (written copy)
of your assignment.
6. Soft copy – Scan your written assignment in the PDF format, save it as a PDF file, with the file
name as follows: CHF02 Assignment_surname_first name_ID number, for example, CHF02
Assignment_Bilimoria_Veena_S11XXXXXX, AND upload it in the Assignment drop box
available in the Assignment block of CHF02 Moodle page. The assignment block will be
available in Week 13. For Regional students who are not able to scan, you can take pictures of
your answers, copy and paste the pictures in a word document, save it as a PDF file and then
name the file correctly and upload as stated above. Please ensure that the pictures of your
answers are copy-pasted in a word document and converted to PDF file are readable and clear.
7. Hard copy – Regional campus students – you need to hand deliver the hard copy of your
assignment to your respective Pacific TAFE Campus Coordinators / Facilitators Office.
School-Based students – give the hard copy of your assignment to your school principals.
Laucala students – you need to drop the hard copy of your assignment in the assignment box
at the Pacific TAFE office, Level B, Library foyer, USP Library, Laucala Campus.
8. Please ensure that you have uploaded a soft copy (scanned copy) on CHF02 Moodle page
before submitting the hard copy of your assignment.
9. You are most welcome to message the Course Coordinator or Facilitators, if you have any
queries.
In this assignment, there are 12 long answer type questions, which are based on concepts
covered in UNIT 4 – 12.
UNIT 4
Question 1 (7 marks)
75.0 g of MnO2 reacts with 75.0 g of HCl to produce MnCl2, Cl2 and H2O. The limiting reactant is
HCl. The equation for the reaction is
MnO2 (s) + 4HCl (aq)  MnCl2 (s) + Cl2 (g) + 2H2O (l)
a) Explain the difference between a limiting reactant and an excess reactant.
b) Calculate the theoretical yield (in grams) of chlorine (Cl2) gas that would form according to the
above chemical reaction.
c) If the percentage yield of chlorine gas in the above reaction is 89.5 %, calculate the
experimental yield of chlorine gas in grams.
(2 + 3 + 2 = 7 marks)
UNIT 5
Question 2 (10 marks)
A cosmetic company manufactures hand sanitizers, and one of the main ingredients used is 70.0 %
isopropyl alcohol by volume. [Note: The density of isopropyl alcohol is 0.786 g/cm3
and Mr of
isopropyl alcohol (CH3CHOHCH3) is 60.0 g/mol]
a) What is the IUPAC name of isopropyl alcohol?
b) Calculate the molality of isopropyl alcohol.
c) Calculate the molarity of isopropyl alcohol.
d) Calculate the % by mass of isopropyl alcohol.
e) Calculate the ppm by mass of isopropyl alcohol.
(1 + 3 + 2 + 2 + 2 = 10 marks)
Question 3 (5 marks)
Chloroquine (C18H26CIN3) has been widely promoted across the world as a drug that may treat the
disease COVID-19. It is currently used as an anti-malarial drug and is soluble in dilute acids and
slightly soluble in water. In the lab, a student wanted to dissolve a certain amount of this drug in a 0.01
mol/dm3
(M) hydrochloric acid (HCl) solution. The lab chemical stock room has a 37.0 % by mass of
HCl stock solution, with a density of 1.2 g/cm3
.
a) Calculate the molarity (M) of the 37.0 % by mass of HCl stock solution.
b) With the use of appropriate calculations/working, explain how the student would dilute the
hydrochloric acid stock solution to a 250.0 cm3
of 0.01 M hydrochloric acid solution.
(3 + 2 = 5 marks)
UNIT 6
Question 4 (5 marks)
Lead (Pb) (average atomic mass 207.19 amu) has three naturally-occurring isotopes, Pb206, Pb207and
Pb208 with isotopic masses of 205.98 amu, 206.98 amu and 207.98 amu respectively. If the isotopes
Pb207and Pb208 are present in equal amounts, calculate the percent abundance of each isotope of Pb,
which are, Pb206, Pb207 and Pb208
.
UNIT 7
Question 5 (3 marks)
a) Explain in your own words, what is “electron wave-partial duality”.
b) A student was observing an emission spectrum of a substance and observed a number of series of
spectral lines. One of these series consisted of four spectral lines in the visible region, where
each spectral line had its own distinctive color that is, red, blue-green, blue-violet and violet. The
illustration of the emission spectrum is given in Figure 1 below.
Figure 1: Illustration of the emission spectrum of a substance.
Based on these observations, assist the student in answering the following questions.
i) Name of Series:
iii) Name of the substance:
(1 + 2 = 3 marks)
Question 6 (7 marks)
Across the world, the use of thermometers to check human temperature is considered to be one of the
tools to screen for the virus COVID-19. Some of these thermometers are able to detect temperature
from a particular distance, therefore, preventing close contact between humans and the spread of the
virus. Such thermometers are able to sense a specific energy (electromagnetic radiation) emitted by the
human body.
a) Name this electromagnetic radiation (EMR) that is emitted by the human body.
b) Based on your answer in a), does this EMR have a lower or higher frequency than the x-ray
radiation used in medical equipment. Justify your answer using frequency range of both EMR.
c) Based on your answer in a), does this EMR have a shorter or longer wavelength than the visible
radiation. Justify your answer using wavelength range of both EMR.
d) State the relationship between frequency, wavelength, and energy of electromagnetic radiation.
e) If the energy of the EMR emitted from a COVID-19 patient with high fever is 9.94 x 10
-24 kJ,
calculate the wavelength (in nm) and frequency (in Hz) of the EMR emitted.
(0.5 + 1 + 1 + 1.5 + 3 = 7 marks)
Question 7 (5 marks)
Neil Bohr provided the modern concept of the atomic model. According to Bohr, the atom is made of
a central nucleus containing protons (positively-charged) and neutrons (with no charge). The electrons
(negatively-charged) revolve around the nucleus in different imaginary paths called orbits or shells. He
also proposed the planetary model of the hydrogen atom and he successfully explained hydrogen
spectra.
a) State two limitations of Bohr’s model.
b) An electron in a lower energy level (n1) absorbs 4.0875 x 10-19 J of energy and moves to a higher
energy level of n2 = 4, calculate the value of n1. [Note: A = 2.18 x 10-18 J]
Question 7 continued …
c) A successful feature of Bohr Model was that his theory accounted for the Rydberg equation,
which made it possible to calculate wavelengths of the hydrogen spectral lines. Using the
Rydberg equation, calculate the wavelength (in nm) of a spectral line produced in the hydrogen
spectrum, when an electron falls from the 4th energy level to the 2nd energy level. Which region
of the electromagnetic spectrum does this spectral line belong to?
[Note: Rydberg constant, RH = 109,678,00 m-1
]
(1 + 2 + 2 = 5 marks)
UNIT 8 and UNIT 9
Question 8 (15 marks)
Based on the original Bohr Theory, Erwin Schrödinger, a Nobel Prize-winning Austrian-Irish
physicist, completed the most comprehensive description of the electronic structures of atoms. A
powerful model of the atom was developed by Erwin Schrödinger in 1926. Schrodinger replaced
Bohr’s well-defined orbits with probability “clouds”, called “orbitals.” The difference between orbit
and orbitals is important to understand for any budding chemistry student or even professionals in the
field of chemistry.
a) What is an atomic orbital and how does an atomic orbital differ from an orbit?
b) In quantum theory/mechanics, three quantum numbers are required to describe the distribution of
electrons in hydrogen and other atoms. For each one of these three quantum numbers, state the
name, symbol and the feature of the orbital described by each.
c) State the name, symbol and the feature described by the 4th quantum number.
d) Draw the table below in your assignment and complete the table for n = 2.
Shell
(n)
Subshell
(l)
ml ms Set of
quantum numbers
(n, l, ml, ms)
Sub-shell
designation
No. of
orbitals
No. of
electrons
Electron
configuration
2
e) State the Pauli Exclusion Principle.
f) What is the maximum number of electrons that can be accommodated in each of the following?
i) n = 3
ii) a 4d subshell
iii) a 2p orbital
iv) n = 3, l = 0, ml = 0, and ms = – ½
g) Write the set of quantum numbers for the 5th electron in nitrogen atom.
(1 + 3 + 1 + 5 + 1 + 2 + 2 = 15 marks)
Question 9 (15 marks)
a) State the Aufbau Principle and Hund’s Rule.
b) State the name of the principle or rule (Pauli Exclusion Principle, Aufbau Principle or Hund’s
Rule) that is being violated in each of the following orbital diagram notation for ground state
elements.
i)
Principle/rule violated: __________________
1s 2s 2p
ii)
Principle/rule violated: __________________
1s 2s 2p
c) Write the electron configuration for oxygen atom (O) and ferric ion (Fe3+
) using s, p, d, f
notation and the orbital diagram notation.
d) For the following species:
Mg and Cr2+
i) Write the electronic configuration using the noble gas notation.
ii) Draw the partial orbital box diagram showing valence electrons for the above species
(Mg and Cr2+), and indicate whether they are paramagnetic or diamagnetic.
e) Determine the number of electrons in the outer occupied shell of each of the following elements,
and indicate the principle quantum number of that outer occupied shell.
Number of electrons
in outer occupied shell
Principle quantum number of
that outer occupied shell
(i) Na n =
(ii) Cl n =
(2 + 1 + 5 + 5 + 2 = 15 marks)
UNIT 10
Question 10 (10 marks)
a) Explain the term, atomic radii and state the trend in atomic radii up the group (bottom to top) and
across the period (left to right) in the periodic table.
b) Explain the term, electronegativity and state the trend in electronegativity up the group (bottom
to top) and across the period (left to right) in the periodic table.
c) Using the periodic table, rank the atoms in the following set in order of increasing (from lowest
to highest) atomic radii and electronegativity.
Mg, S, F, Cs
d) Draw suitable diagrams and explain whether CH4 and CH3Br molecules have net dipole
moment or not and whether the molecule is polar or non-polar.
(1.5 + 1.5 + 4 + 3 = 10 marks)
  
  
UNIT 11
Question 11 (10 marks)
a) What is the basic principle of VSEPR Theory?
b) Draw the table below in your assignment and use the VSEPR theory to complete it.
No. of
electron
pairs on
central atom
No. of
bonding
pairs
No. of nonbonding
pairs (or
lone pairs)
Basic Geometry Final shape
3 3 0 Trigonal planar
4 2 2
6 5 1 Octahedral
c) Draw the Lewis structure and use VSEPR theory to predict the basic geometry (electron-pair
geometry) and final shape (molecular geometry) of CO3
2-
and SCl4.
(2 + 2 + 6 = 10 marks)
UNIT 12
Question 12 (8 marks)
a) Explain, hydrogen bonding, using a suitable example.
b) State the strongest intermolecular force that exists between molecules of the following
substances.
i) KBr
ii) HF
iii) CH3Cl
iv) CO2
c) i) State and explain the relationship between the strength of intermolecular forces and
surface tension of liquids.
ii) Which substance will have a higher boiling point, ammonia (NH3) or methane (CH4).
Explain your answer in terms of intermolecular forces.
(2 + 2 + 2 + 2 = 8 marks)
ALL THE Best !!!

 
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