Sept 15 Problem 1 and 2 Worked Solutions PDF

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concepts in chemistry lecture notes fall 2021...

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Chem1011/1021 Lecture Handout – Sept 15, 2021 Problem 1 Homeopathic “medicine” is based on natural and herbal remedies and, often incorporates the idea that less is more. For example, a high potency homeopathic “drug” often is diluted to “200C”. This means that a substance is diluted such that there is 1 part of the substance (solute) in 100 parts of the solvent (typically water or ethanol) 200 times over with a special mixing technique called “succussion” in between each dilution.(1) Botulinum toxins are widely regarded as the most toxic substances on earth. These is a natural substances produced by the anaerobic bacteria clostridium botulinum and are responsible for botulism food poisoning. Despite this, botulinum toxins are also commercially used for cosmetic purposes such as Botox and medicinally for relief of muscle spasms and migraines due to its paralytic properties.(2) The LD50 of a botulinum toxin is very, very small – about 2 ng/kg is enough to kill a human when taken by injection.(3) Considering an adult weighing 90 kg and that the LD50 level is lethal, this means that injecting only 0.18 ȝg of botulinum toxin could cause death (for reference, a single grain of rice weighs 116,667 times that at 21 mg(4)). Imagine a homeopathic practitioner were to prepare a 12C solution of botulinum toxin to be injected into a 90 kg adult human. In order to do so, the homeopath prepares 1 L of a 1.0 mol/L solution of botulinum toxin. In order to do the dilutions, the homeopath takes this 1 L of solution and dilutes it with more solvent such that the solution now has a volume of 100 L. This solution is considered a 1C solution. The homeopath then takes 1 L of the 1C solution and dilutes it with more solvent such that the solution now has a volume of 100 L. This solution is considered a 2C solution. The homeopath continues with this process 10 more times until they have reached a 12C solution of botulinum toxin. Question(s): 1. What is the concentration in mol/L of the final 12C solution? 2. How many molecules of botulinum toxin are there in 1 L of the 12C solution? What about 1 mL of the 12C solution? 3. What would be the lethal dosage of the 12C solution by injection for a 90 kg adult, considering that botulinum toxin has a molar mass of approximately 149 000 g/mol.

References (1) “The Curious “Science” of Oscillococcinum” https://www.mcgill.ca/oss/article/homeopathy/curious-science-oscillococcinum (2) “Handle with care – the world’s five deadliest poisons” https://theconversation.com/handle-with-care-the-worlds-five-deadliest-poisons-56089 (3) “Wikipedia: Botulinum toxin” https://en.wikipedia.org/wiki/Botulinum_toxin (4) “The Measure of Things: How heavy is 0.021 grams?” https://www.themeasureofthings.com/results.php?comp=weight&unit=gms&amt=0.021

CopyrightConceptsinChemistry,DepartmentofChemistry,DalhousieUniversity

©2021

Problem 2

In our lifetime, several super heavy elements (elements with more protons than Uranium) have been discovered, verified and as such, officially named and added to the periodic table. For example, in November 2016 Nihonium (#113), Moscovium (#115) Tennessine (#117) and Oganesson (#118) all became a part of the periodic table.(1) These so called “super heavy elements” only exist synthetically on Earth, and are created in particle accelerators when nuclei of smaller elements join together in nuclear fusion reactions. For example, Oganesson is created by bombarding californium atoms with a beam of calcium atoms (98Cf + 20Ca = (2) 118Og) . Additionally, similar high energy nuclear fusion reactions can occur in the cores of stars and in supernova explosions. For example, einsteinium, which was thought to only exist synthetically, is observed in nature in Pryzybylski’s star (albeit 355 light years away)(3). Yuri Oganessian, a still living Russian physicist who has played a huge role in shaping the “heavy part” of the periodic table and for whom Oganesson is named, dreams of expanding the periodic table even further to elements 119 and 120 at his lab which is called the “Superheavy Element Factory” (SHEF).(4) Imagine that Oganessian is successful in this endeavour and discovers element 120. In the sample that is created, 5% of the sample is found to have 180 neutrons, 18% of the sample is found to have 186 neutrons and the rest of the sample is found to have 192 neutrons.

Question(s): 1. What would the isotopic notation be for each of the newly created isotopes? Use “X” as the element symbol as this theoretical element has not been named yet! 2. If we assume that the mass each proton and neutron is 1 amu, what will be the average atomic mass of element 120 in amu to the nearest whole number? 3. For fun – what would you name a new element if you had the chance?!

References (1) “Names and symbols of four newly discovered elements announced” https://www.sciencedaily.com/releases/2016/12/161202123622.htm#:~:text=On%2028%20No vember%202016%2C%20the,115%2C%20117%2C%20and%20118. (2) “Wikipedia: Oganesson” https://en.wikipedia.org/wiki/Oganesson (3) “Wikipedia: Przybylski’s Star” https://en.wikipedia.org/wiki/Przybylski%27s_Star (4) “A storied Russian lab is trying to push the periodic table past its limits – and uncover exotic new elements” https://www.sciencemag.org/news/2019/01/storied-russian-lab-trying-pushperiodic-table-past-its-limits-and-uncover-exotic-new

CopyrightConceptsinChemistry,DepartmentofChemistry,DalhousieUniversity

©2021...