Chemistry Issues - Assignment Example

EXAMINATION al Affiliation: Colorado - Pueblo Chemistry 101 Independent Study Examination _______________________________________________ 1. (10 pts) Critique the following assertion made in the advertisement of a commercial product: "This product contains no chemicals." Chemicals constitute everything on Earth, except a few elementary particles that exist in minute quantities from sunlight and solar wind or radioactive decay. Therefore, it is not possible to have a product that does not contain chemicals. Often, such adverts attempt to imply that the product have no exceptionally toxic or harmful chemicals. However, since there is some stigma attached to the word ‘chemical’, most adverts use it without clarification. 2. (10 pts) Which concerns you more - pesticide residues on supermarket produce or second- hand cigarette smoke? Why? Second-hand cigarette smoke concerns me more than pesticide residues on supermarket produce. Although the later is also dangerous, second-hand cigarette smoke has contributed to many diseases and deaths. Tobacco smoke contains more than 5,000 chemicals in the form of particles and gases. About 300 of them are harmful and at least 70 cause cancer. Cigarette smoke leads to lung cancer and breast cancer. It also causes heart diseases, asthma, respiratory infections, and many other health complications to non-smokers. Consequently, a lot of money goes towards treating the diseases. Many people succumb to the illnesses, leading to loss of labor force. The fact that cigarette smoke is a problem at work, in public place, at home and in the car only worsens the situation. 3. ( 12 pts) Provide a short definition for the following terms: A. element The simplest chemical substance that contain only one kind of atom, and cannot be disintegrated into other substances using chemical means. B. compound A chemical substance that contains atoms of two or more different elements bonded together chemically. The composition has a fixed ratio of each element. C. solution A homogeneous mixture where a solute has been dissolved in a solvent. D. organic chemistry The scientific study of properties, structure, reactions, composition and preparation of compounds that contain carbon is called organic chemistry. E. isotopes They are atoms of the same element that have different numbers of neutrons. F. atomic orbital It is a mathematical function, which determines the probability of finding an electron of an atom in a particular region around the nucleus. 4. ( 10 pts) A typical speed limit in Canada is 100 km/hr. What is this in miles/hour? Show your work for credit. 1 kilometer = 0.621371 miles 100 km = 100 x 0. 621371 = 62. 13 miles/hour 5. ( 6 pts) Arrange the elements below into three different groups that have similar chemical properties. cesium chlorine magnesium barium potassium lithium bromine sodium fluorine calcium Group I: Cesium, Potassium, Lithium, Sodium Group II: Magnesium, Barium, Calcium Group VII: Chlorine, Bromine, Fluorine 6. ( 7 pts) You move into a home found to have a radon level of 3 pCi/L. What does this mean? Should you be concerned about radon exposure at this level? Why or why not? The home has a radon radioactive concentration of 3 picocuries per liter. I should be concerned because a short-term test result is usually within a factor of 3 of the long-term average. Therefore, the home may have a higher radon exposure in the long-term in the range of 1-9 pCi/L. Future radon level above 4 pCi/L will lead to cancer and death. 7. ( 10 pts) Explain, in terms of intermolecular forces, why you can ice skate in the winter? In other words, why does ice float on water when other solids do not float on top of their liquid phases (a lead bullet dropped into molten lead will sink to the bottom)? Ice floats on water due to the hydrogen bonding intermolecular forces. Water has two O-H polar covalent bonds in a “bent” molecular geometry. It has an overall dipole moment since each O-H bond has a dipole moment that points in the same direction. The oxygen atom is partially negative while the Hydrogen atoms are partially positive since the Oxygen atom pulls the pair of electrons towards itself away from the hydrogen atoms. The partial positive Hydrogen of one molecule attracts the partial negative Oxygen atom of a neighboring molecule. Thus, neighboring molecules end up forming interlocking networks due to strong Hydrogen Bonding. Other substances may lack the Hydrogen bonding. Freezing causes water molecules to slow down and strengthen the hydrogen bonding. The hydrogen bonding together with the bent shape of water molecules leads to a 3-D hexagonal arrangement. The array creates empty spaces in the lattice structure and reduces the number of molecules per unit volume. The reduction in molecules leads to less mass per unit volume. The solid, therefore, is less dense than the liquid, leading to floating. 8. ( 10 pts) The gas in a sealed bag of CheetosTM has a volume of 500 mL in Pueblo where the atmospheric pressure is 600 mm of Hg. You take this bag to the top of Pikes Peak where the pressure is 420 mm of Hg. Assuming the temperature on the Peak is the same as Pueblo ( the hot day on the Peak!), what is the volume of the gas in the CheetosTM bag on the Peak? Show your work. V1=500ml P1= 600mmHg P2=420 mmHg V2=? P1 x V1 = P2 x V2 600 x 500 = 420 x V2 Therefore, V2= 600 x 500 =714.29 ml 420 9. A. ( 5 pts) Balance this equation: 3H2(g) + N2(g) --> 2NH3(g) B. ( 5 pts) How many moles of ammonia could be produced from 20 moles of nitrogen and 5 moles of hydrogen? Show work for credit. Ratio = 3:1:2 Nitrogen is in excess Therefore, NH3 = 5 mol H2 x 2 mol NH3 3 mol H2 = 3.333 moles 10. ( 5 pts) Lipids (fats) are esters of long chain fatty acids and glycerol. Similarly, describe the general structures of proteins and carbohydrates. In other words, what are the monomers that these biological polymers are composed of? Proteins are nitrogenous organic compounds whose molecules consist of several long chains of amino acids monomers. Carbohydrates are polysaccharides that consist of simple sugar monomers such as fructose, glucose, and lactose joined in long chains. 11. ( 5 pts) What is the difference between soap and detergent? Soap is a salt formed from a metal (mainly alkali or alkaline earth metals) and a fatty acid ( of natural origin-plant or animal). The fatty acid has an aliphatic carbon chain with a carboxylic acid group at its end. Soaps are insoluble in mineral water. A detergent is synthetic in nature. It has a sulfate or sulfonate group instead of a carboxylic acid group. They can also have one or more aromatic rings. Detergents may act as foaming agents and surfactants due to additional properties. 12.(5 pts) What is the purpose of spreading lime, CaCO3, on soil? Spreading lime (CaCO3) reduces the excessive level of acid in the soil to promote soil fertility for plant growth. An excess amount of acid in soil lowers growth of a plant by hindering absorption of major plant nutrients such as potassium, phosphorus and nitrogen. Such nutrients tend to dissolve in acid and leach to lower levels of the soil beyond the reach of the plant. Reference Joesten, Castellion & Hogg. 4 th Ed. (2007). The World of Chemistry Essentials. CengageBrooks Cole Publisher. ISBN-10: 0495012130 ISBN-13: 9780495012139 Read More