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Unformatted text preview: Problem Set 1 1 The following are metric numerical prefixes. Identify the exponent that corresponds to the scientific notation for each. Giga 10^9 Mega 10^6 Kilo 10^3 Hecto 10^2 Deca 10^1 Deci 10^1 Centi 10^2 Milli 10^3 Micro 10^6 Nano 10^9 Pico 2) The following are the diameters of 2 different cells. Mycoplasma Plant cell A) Calculate the surface area and the volume of both cells. (Help: SA=(4)(3.14)(r^2)=(3.14)(d^2), V=(4/3)(3.14)(r^3)=(4/3)(3.14)(d/2)^3) Mycoplasma SA>> (3.14)*(20*10^9)^2=1.2560e015m^2 d=20nm(nanometers) d=50m(micrometers) 10^12 V>> (4/3)*(3.14)*((20*10^9)/2)^3= 4.1867e024m^3 Plant cell SA>> (3.14)*(50*10^6)^2= 7.8500e009m^2 V>> (4/3)*(3.14)*((50*10^6)/2)^3= 6.5417e014m^3 B) Calculate the ratio of the diameter, surface areas, and of volumes between the 2 cells. (Mycoplasma/plant cell) Comment on your observations D(Mycoplasma/Plant cell)=(20*10^9)/(50*10^6)= 4.0000e004 SA(Mycoplasma/Plant cell)= (1.2560e015)/(7.8500e009)= 1.6000e007 V(Mycoplasma/Plant cell)= (4.1867e024)/(6.5417e014)= 6.4000e011 The ratios of the diameters is 4*10^4, the ratio of the surface ares is the square of the diameters, and the ratio of the volumes is the cube of the diameter. So the relationship is NOT linear and the volume grows with an increase of the diameter cubed and the surface area only grows as the diameter squared. 3) Give a unique example of each of the following characteristics of life. Are any of these characteristics evident in nonliving systems? Answers will vary, many correct responses Order spiral pattern on pineapple, nonliving example, incredible order in ionic solids long neck of giraffe, wings on birds to fly, fins on aquatic mammals and fish, etc. dilation of pupil in eye due to change in light level, nonliving example, rock heating up due to radiation from sun Sexual reproduction Evolutionary adaptaion Response to environment Reproduction Growth and Development growing from caterpillar to butterfly, growing from juvenile to adolescent, to a mature organism, nonliving example, icicle or stalagmite growing over time from addition of more material(water or minerals) Biological metabolism, converting sugars and oxygen to energy, nonliving example, nuclear reactions in core of the sun cooling of body temperature in an elephant with large thin ears, nonliving example, convection currents in ocean and atmosphere regulate the temperature on earth such that it does not fluctuate to thousands of degrees under the radiation of the sun and near zero at night. Energy processing Regulation 4) An atom is a basic unit of matter consisting of a dense central nucleus surrounded by a cloud of negatively charged electrons. A) What are the 2 subatomic particles discussed in class that make up the nucleus? Proton, neutron B) List a similarity and a difference mentioned in class between these 2 particles. They both have the same mass, the proton is positively charged while the neutron is neutral (no charge) C) These particles determine both the atomic number and the mass number. What does each number mean and how is each determined. The number of protons in the nucleus determines the atomic number, and the protons and neutrons together determine the mass number. The atomic number identifies the type of atom/element it is The mass number is the atomic mass (electrons are involved in the determination of the mass because their mass is negligible compared to protons and neutrons) D) Imagine that you have 2 different particles. If they have different atomic number, what does this mean? If they have different mass number what does this mean? What does it mean if they have the same atomic number and different mass numbers? What does it mean if they have the same mass number and different atomic numbers? Different atomic numberdifferent elements Different mass numberdifferent total of protons and neutrons Same atomic number, different mass number different isotopes Same mass number, different atomic number different elements and different number of neutrons, but sum of both are same 5) A) Identify each of the following 2 letter elemental abbreviations. Oxygen Carbon Hydrogen Nitrogen Calcium Phosphorus Potassium Sulfur Sodium Chlorine Magnesium B) An atomic ion is an atom with a different count of protons and electrons. For each of the above elements indicate the charge of its most likely monoatomic ion. O C H N Ca P K S Na Cl Mg 6) A) 2 +/4 +1 3 +2 3 +1 2 +1 1 +2 The elements in the first 2 columns in the periodic table of elements are metals, and the elements in the top right portion of the periodic table are nonmetals. Is there a trend between ionic charge and whether it is a metal or nonmetal? Yes, metals are generally create positively charged ions(cations), whereas nonmetals generally create negatively charged ions(anions). B) Suggest a possible explanation for the observed trend. The above identified trend is due to the valence of the element. The octet rule is a simple chemical rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas. All of the metals(in left colums) discussed in class have one or two valence shell electrons. To form a stable shell complying with the octet rule, these electrons are lost to more electronegative atoms, and form cations. Similarly, the more electronegative nonmetals complete their outer shell by stripping electrons from metals. 7) Interatomic and intermolecular interactions were discussed in class. List the 4 mentioned in order of decreasing strength. Covalent Ionic Hydrogen Van der waals 8) A) A molecule consists of 2 or more atoms that are covalently bonded. Draw the following molecules(Lewis Dot). Make sure to indicate what electrons are being shared. (Hint: All of the following molecules are neutral, what does this tell you about the number of electrons?) O2 H2O CO2 CH4 B) Label all polar covalent bonds in the above molecules Bonds between OH are polar with the partial negative on the oxygen side Bonds between OC are polar with the partial negative on the oxygen side For O2 and methane, no polar bonds 9) A) Ionic interactions play a large role in biology. Give 4 examples of an ionic compound. NaCl MgCl2 NaF LiI B) These ionic compounds are also called salts. Salts do not have to be composed of inorganic monoatomic cations and anions. Give 3 examples of salts that have at least one polyatomic ion. Sodium Nitrate Lithium Hydroxide Sodium Acetate 10) A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. R) In the following Identify which compounds are molecules identify which compounds are ionic compounds balance each equation All molecules Na+ NO3 Li+ OH Na+ CH3CO2 N2 + 3H2 2NH3 6H2O+6CO2 C6H12O6+6O2 All Molecules 2Na(s)+2HCl(aq) 2NaCl(aq)+H2(g) All ionic except for H2 11) A salt is also defined in chemistry as an ionic compound that can result from the neutralization reaction of acids and bases. In its most basic form, an acid can be defined as any substance that increases hydrogen ion (actually hydronium ion) concentration. i.e. HCl H++Cl Similarly a base can be described as any substance that reduces hydrogen ion concentration of a solution.i.e. NaOH +H+ Na+ +OH+H+ Na++H2O Suppose that you have 500mL of 1 M HCl, and .75M NaOH. What is the initial pH of each? What is the concentration of OH and of the H+? pH(HCl)=log[H+] =log(1)=0 pOH(NaOH)=log[OH]=log(.75)= 0.1249 ; pH(NaOH)=14pOH(NaOH)=140.1249=13.8751 [H+]=1 [OH]=.75 12) A buffer is a solution which reduces the change in pH upon addition of small amounts of acid or base, or upon dilution. Why are buffers be critical to biological systems? Changes in pH can change chemical reactivity, solubility, structure, and function of molecules and ions. The ability to synthesize buffers and maintain a constant pH in the presence of a constantly changing environment allows for the proper functioning of a systems vital processes. 13) The four emergent properties of water discussed in class are 1)cohesion 2)moderation of temperature; a)high specific heat, b)evaporative cooling 3)insulation by floating ice 4)solvent properties Identify each of the following observations in nature with one of the above emergent properties of water. Water reaches the tip of a giant red wood tree 100m tall without any pumps or any mechanical forces. Small bugs can walk on water. Local temperature around the great lakes, and in coastal areas is cooler during the summer and warmer during the winter. Water on the bottom of lakes in Russia does not freeze even with cold winds blowing less than 20 degrees celcius. Dogs panting on hot days. A can of rockstar energy drink has 12 tablespoons of delicious sugar, but you do not see a single sugar crystal as you drink it. Water spots on your car after it rains. Cohesion Cohesion High specific heat Insulation by floating ice Evaporative cooling Solvent properties Solvent Properties 14) Although cells are 7095% water, life on earth is termed "Carbon based." Most of the 530% that is not water is composed of carbon based compounds. Carbon can almost always make 4 bonds. Isomers are molecules with the same molecular formula (i.e. they have the same type and number of atoms) but have different structures and properties. Give one example of each of the following types of isomer and be sure to include a pictorial representation drawing attention to the difference that uniquely identifies each isomer. Try to do this without looking at your notes based on a carbon chain. Structural Geometric Enantiomer Perfect illustration given in lecture 3 slide 10 15) Some biological molecules consist of thousands of atoms. They each have functional groups. A) What is a functional group? A functional group is the part of the molecule involved in chemical reactions, or changes the chemical reactivity of a molecule B) Draw each of the following functional groups Perfect illustrations given in lecture 3 slides 1520 C) Try to identify some use or function in everyday life that is caused by the above functional groups. Hydroxyl Carbonyl Carboxyl all alcohols have hydroxyl groups, including ethanol acetone aka fingernail polish remover has a carbonyl group acetic acid aka vinegar is on your healthy salads Amino Sulfhydryl Phosphate fertilizers and psychoactive drugs have amino groups hair straightening and perms are the rearrangement of the sulfhydryl bonds in your hair the energy you burn studying, running, etc. is derived from the energy in phosphate bonds One of the main differences between testosterone and estradiol, and many other hormones, are the placement of 3 methyl groups, the ratio of these 2 hormones is responsible for expression of sexual characteristics, Methyl ...
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This note was uploaded on 10/11/2009 for the course BILD 1 taught by Professor Kiger during the Spring '09 term at CSU Northridge.
- Spring '09