...It is widely agreed upon that Dmitri Mendeleev is the father of the periodic table of elements that we are all familiar with today. That is at least debatable considering Lothar Meyer came up with a very similar table to Mendeleev’s. The crucial difference between these two is Dmitri’s was to get his widely published before Meyer, thus earning him the credit for developing the table. Before they were able to even assemble elements into an orderly manner, some important things had to happen first. Before it would be possible to even group elements together in an organized way, there, of course, had to be enough elements discovered to populate such a table. Many elemts have been known since thousands of years ago. The first scientific discovery of an element was the discovery of phosphorous in 1649 by Henning Brand. For 200 years following his discovery, science acquired a vast knowledge of elements and their properties. There were so many different elements, it was determined there must be a way to separate them into groups, if only for the sake of convenience. The earliest attempt to divide elements into gases, metals, non-metals, and earths was made by Antoine Lavoisier. For many years after his organization attempt, scientists all over the world began to learn about elements and how certain ones were similar to others. They used this information to make their own version of how they should be grouped together. It was eventually recognized that there should be a universal...
Words: 407 - Pages: 2
...Chem 200 (8/28) * Chapter 1 and 2 homework ( paper) turn in next week (wed) pg 217 in lab manual * Quiz 1 in discussion sections next week * Connect homework is live -chapter 1 and 2 due sept 6 * Know common elements and ions-lab manual/syllabus pages 14-16 * Read Chapters for exams Notes Errors in measurements * Radom error: all measurements have some level of random error they can be either positive( measure more than you actually do ) or negative errors( measure less then you usually do ) * Systematic error: always the same direction (either positive or negative) Precision and Accuracy * Precision : how reproducible each measurement is , how close each measurement is to the other measurements * Accuracy : how close the measured values are to the true value. Temperature Conversions (on the exam) Chemical Language * Elements (Na,Cl)- letters of the language * Chemical Formulas (NaCl)- words of the language Water Vs. Hydrogen Peroxide (on the exam) * The use of Hydrogen peroxide: nuclear, bomb, bleach hair,etc * Molecular formula : water: H2O, Hydrogen Peroxide : H2o2 * Empirical Formula: water HO, Hydrogen peroxide: HO * Structural Formula : water HOH, hydrogen peroxide: HOOH quetion: how many atoms of carbon, hydrogen, and oxygen are present in a single molucule of citric acid C3H5O(CO2H)3 Carbon: 6 Hydrogen :8 Oxygen: 7 Chemical Bonding * Bonds form between atoms when they share electrons *...
Words: 1057 - Pages: 5
...The chemistry of perming & rebonding Some of us have naturally curly hair but want it straightened; others have it naturally straight but want it curly. But whatever the style you like to wear, there's chemistry involved in it! The structure of hair Hair is made mostly of a protein called keratin, which is also present in nails. In hair, keratin molecules are arranged in straight bundles. These bundles are held together by disulphide bonds (-S-S-), which give strength to the hair. Disulphide bonds are made by the amino acid called cysteine. The cysteine of one keratin molecule forms a disulphide bond with the cysteine of the neighbouring keratin molecule. The more disulphide bonds there are in a strand of hair, the straighter it is. Ammonium thioglycolate: the perm salt Ammonium thioglycolate (HSCH2CO2NH4) is a compound that can break disulphide bonds. This is because it contains a thiol group (-SH). The thiol group replaces one of the sulphur atoms in the disulphide bond, like this: Keratin-S-S-keratin + 2HS-CH2CO2NH4 --> -HO2CH2CS-SCH2CO2H + 2NH3 + 2HS-keratin When the disulphide bond is broken, the keratin bundles come apart, and hair is weakened. Ammonium thioglycolate is therefore used widely in beauty parlours when customers want their hair re-styled. However, if you use too much of it, or if the reaction is left for too long, you could end up going bald. So do not, ever, try it at home! If you have watched the film Legally Blonde, you'll have seen Reese Witherspoon (acting...
Words: 7009 - Pages: 29
...Some stuff to take note in chemistry IONIC Equations * You have an equation * Split only the aqueous parts * Leave solid, liquid and gas * Cancel out the products that remain the same as he reactants * These are called spectator ions * Methods for preparation of salts * Precipitation * Titration * Uses of salts * Food: Flavoruings, fillers etc * Fertilizers: Ammonium Nitrate (NH4NO3), Potassium Nitrate (KNO3) * Industrial: Modifying properties of cement mixtures, paint formulations, fillers in plastics, inks, medical industry * aHarvesHh ccscHarvesting sea salts, via evaporation, we know it’s a salt cos when you remove the metal and add h , you getan acid * the saltsttttttTHe salts are formed when the H of an acid is replaced by a metal * NaOH + H2So4 -->2NaOH + H2SO4 Na2SO4 + 2H2O * Oxides OosdoidikcxzjOxides and hydroxides are not salts * SoCcCCCCos when you replace the Metal with H, you get H2O =/= Acid * However, water can be considered an acid, sometimes * Nitrates | * All soluble | * Sulfates | * All soluble except clb (calcium lead barium) | * | * Mnemonics: Chinese language b | * Chloride | * All soluble except lms (lead, mercury, silver | * | * Learning management system, | * Carbonate | * All insouluble except spa (sodium, potassium, ammonium) | * | * Science practical assessment | * Precipitation: Prepare insoluble salt: 2 aqueous...
Words: 479 - Pages: 2
...Name: College ID: Thomas Edison State College General Chemistry I (CHE-111) Section no.: Semester and year: Written Assignment 3: Mass Relationships for Compounds Answer all assigned questions and problems, and show all work. 1. How many atoms are there in 5.10 moles of sulfur (S)? (6 points) 1 mole= 6.02 x 1023atoms 5.10 = (Reference: Chang 3.13) 2. How many moles of calcium (Ca) atoms are there in 77.4 g of Ca? (6 points) No of moles = mass of compound/ molar mass of compound (Reference: Chang 3.15 3. What is the mass in grams of 1.00 × 1012 lead (Pb) atoms? (8 points) Mass in grams = no of atoms x molar mass of compound / Avogadro’s number (Reference: Chang 3.19) 4. Describe how you would determine the isotopic abundance of an element from its mass spectrum. (6 points) (Reference: Chang 3.32) The mass spectrometer separates isotopes on the basis of their charge-to-mass ratio providing a spectrum with a number of peaks. Each peak represents an isotope. The mass of each isotope is determined from the magnitude of its deflection on a spectrum whereas the abundance of each isotope is given by the area of the peak. 5. Cinnamic alcohol is used mainly in perfumery, particularly in soaps and cosmetics. Its molecular formula is C9H10O. a. Calculate the percent composition by mass of C, H, and O in cinnamic alcohol. (8 points) b. How many molecules of cinnamic alcohol are contained in a sample of mass...
Words: 778 - Pages: 4
...Ohler 1 Kyle Hardenbrook Chemistry CP October 16, 2014 It was not right for what I did in chemistry class today. Swinging my apron between my legs and making weird noises is a safety caution. If someone was walking by me swinging my apron I could have knocked something out of their hand and made them drop the item. It could have been glass or a specific chemical that was dangerous and caused more injury towards someone. It was extremely immature and I let my energy get to the best of my actions today in chemistry. Proper actions should be mature and not act like a fool and try to get people’s attention and make them laugh. Being the class clown is nothing to be happy about. If I would have causes an accident then their project could have been jeopardized which means their grade is jeopardized. I don’t want to be responsible for affecting someone’s grade because of my immature acts. If I were to knock something over and it was hazardous I could have a possibility of injuring someone. Chemicals are nothing to mess around with and that’s why you should never mess around in a lab. If I were to hurt someone it could mean being in the hospital and if I were responsible for having someone in the emergency room and to pay for someone’s bills I would feel absolutely horrible. Being immature in lab and having fun is nothing to joke about. You need to be 100% serious or else you are endangering other people around your own...
Words: 265 - Pages: 2
...Universiti Tunku Abdul Rahman, Faculty of Science Session : Jan 2015 Subject : UDEC1134 Chemistry Laboratory I Course : Bachelor of Science (Hons) Chemistry Year/Sem : Year 1 T1, T2 & T3 Unit Coordinator : Dr Chee Swee Yong Lecturers : Ms Chang Chew Cheen, Dr Chee Swee Yong, Dr Lim Tuck Meng, Dr Sim Yoke Leng |Lab group |Lab A |Lab B | |Venue |D012A |D012B | |Monday @ 9.00 am – 11.30 am |P5 |P1 | |Monday @ 3.00 pm – 5.30 pm |P2 |P3 | |Wednesday @ 9.00 am – 11.30 am |P3 |P4 | |Wednesday @ 3.00 pm – 5.30 pm |P1 |P2 | |Thursday @ 3.00 pm – 5.30 pm |P4 |P5 | |Week |Experiment |Lab group |Lecturer | |1 |Briefing by HoD |Lab A/ Lab B |Dr Sim KM | | |Expt 1: Investigating...
Words: 463 - Pages: 2
...Freezing Point Depression 4-5: Freezing Point Depression If you dissolve a substance such as ordinary table salt (NaCl) in water, the freezing point of the water will decrease relative to the freezing point of the pure water. This property is used to melt the snow or ice on roads during the winter or to make homemade ice cream. In this assignment, you will dissolve a sample of NaCl in water, add some ice, and then measure the freezing point depression. 1. Start Virtual ChemLab, select Colligative Properties, and select Freezing Point Depression from the list of assignments. The lab will open in the Calorimetry laboratory with a beaker containing 45.00 g of ice and a coffee cup calorimeter on the lab bench. A sample of sodium chloride (NaCl) will also be on the balance. 2. Click on the Lab Book to open it. Record the mass of the sodium chloride in the data table. If it is too small to read, click on the Balance area to zoom in, record the mass, and then return to the laboratory. 3. 100 mL of water is already in the calorimeter. Use the density of water at 25o C (0.998 g/mL) to determine the mass from the volume and record it in the data table. Make certain the stirrer is On (you should be able to see the shaft rotating). In the thermometer window, click Save to begin recording data in the lab book. Allow 20-30 seconds to obtain a baseline temperature of the water. Click the clock on the wall labeled Accelerate to accelerate...
Words: 640 - Pages: 3
...NAME: AKINWANDE OLUFISAYO PARNTNER: COURTNEY DATE: JULY 8TH 2014. ALDOL CONDENSATION TO MAKE VANILIDENEACCETONE. DATA: REACTION: TABLE 1: DATA FROM EXPERIMENT | Vanillin | Acetone | Vanillindeneacetone | Chemical formula | C8H803 | C3H60 | C11H1203 | Molecular weight | 152.25 g/mol | 58.08 g/mol | 192.21g/mol | Density (g/cm3) | 1.06 | 0.788 | | Amount used | | | | Total moles | | | | Theoretical yield | | | | Percentage yield | | | | TABLE 2: DATA FROM EXPERIMENT: REAGENTS | Sodium Hydroxide | Hydrochloric Acid | Chemical formula | NaOH | HCl | Molecular weight | 39.997 g/mol | 36.46 | Denisty | 2.13 | 1.18 | Amount used | 3mL | 7mL | Total moles | 0.i598 | 0.227 | TABLE 3 : IR SPECTRUM Peaks (cm-1) | Functional group | 3699.8 | OH group | 3267.6 | Alkene | 1634.79 | Aromatic | CALCULATIONS: Total moles of Vanillin = 0.5g/152.15 = 0.0033 moles of vanillin. Total moles of acetone = (4mL * 0.788)/ 158.08 = 0.0199 moles of Acetone. Theoretical yields: Vanillin = 0.5g * 1mole * 1mole * 192.21 = 0.632g 152.15 1mole 1mole Acetone = 4ml * 0.788 * 1mole * 1mole * 192.21 = 3.832g 1mole 158.08 1mole 1mole Therefore, vanillin is the limiting...
Words: 487 - Pages: 2
...Name___________________________________ Period____________________________ Date____________ pH/pOH Worksheet H3O+ Molarity to pH 1. Determine the pH of a 0.00118 M solution of HBr. 2. What is the pH of a solution that has a hydronium ion concentration of 1.0 M? 3. What is the pH of a 2.0 M solution of HCl, assuming the acid remains 100% ionized? 4. What is the theoretical pH of a 10. M solution of HCl? OH Molarity to pH 5. What is the pH of a solution with the following hydroxide ion concentrations? a. 1 × 10-5 M b. 5 × 10-8 M c. 2.90 × 10-11 M 6. Calculate the pH of the solution which is prepared by dissolving 32.7 g of sodium hydroxide in 2.50 L of water. OH Molarity to H3O+ Molarity 7. The hydroxide ion concentration of an aqueous solution is 6.4 × 10-5 M. What is the hydronium ion concentration? 8. The hydroxide ion concentration of an aqueous solution is 3.71 × 10-10 M. What is the hydronium ion concentration? Mixed Review 9. Calculate the H3O+ and OH concentrations in a 7.50 × 10-4 M solution of HNO3, a strong acid. 10. What are the pOH and hydroxide ion concentration of a solution with a pH of 8.92? 11. A solution is prepared by dissolving 3.50 g of sodium hydroxide in water and adding water until the total volume of the solution is 2.50 L. What are the hydronium and hydroxide ion concentrations? 12. If 1.00 L of a potassium hydroxide solution with a pH of 12.90 is diluted to 2.00 L...
Words: 383 - Pages: 2
...University of Phoenix Material Week 4 Exercises Prepare written answers to the following exercises: 1. Imagine that you are an environmental scientist. Working in collaboration with a university chemist, you were able to determine from mass spectrometry that four elements exist in your soil samples. They are Se, Sn, Pb, and Cd. You need to determine which elements will most likely combine with oxygen to produce oxides that are present in your sample. To do so, refer to the periodic table to determine the electron configuration and ionization energy of each element. This will show the number of valence electrons for each element. • What are the electron configurations for Se, Sn, Pb, and Cd? Selenium=[Ar]3d 10 4s2 4p4, Tin=[Kr]4d10 5s2 5p2, Lead=[Xe]4f14 5d10 6s2 6p2, Cadmium=[Kr]4d10 5s2 • What are the valence electrons for Se, Sn, Pb, and Cd? Selenium=Valence 6, Tin=Valence 4, Lead=Valence 4, Cadmium=Valence 2 • Rank the elements in increasing ionization energy. Selenium=941.2045, 2973.7, 4144, 6590, 7880, 14990 kj/mol. Cadmium=867.8, 1631.4, 3616 kj/mol, Lead=715.6, 1450.5, 3081.5, 4083, 6640 kj/mol. Tin=708.6, 1411.8, 2943, 3930.3, 7456 kj/mol • Which element will form oxides? Lead. 2. Imagine that, as an employee of a pharmaceutical company, you are working on an H-K-ATPase. It is the enzyme that pumps acid into the stomach to help in digestion. You are trying to determine whether a compound will fit inside the pocket of...
Words: 512 - Pages: 3
...Determination of Chemical formula Joseph Kelly, Anthony Crespi and Darrian Saddler, Wake Technical Community College July 13, 2015 CHM CHM 151 section 4103 Purpose: his las was used to separate the compound into its constituent elements that will help to determine the different molar ratios. Method: The experiment is conducted according to the published procedure in General Chemistry I: CHM 151 Laboratory Experiments, Wake Technical Community College, summer 2014, pp.70-74. Get an analytical balance and zero it to begin this experiment. Then weigh out one gram of copper chloride hydrate use the evaporating dish to weigh this substance. After that, record the mass of the substance. Use a hot plate to heat the evaporating dish and use the temperature to control the crackling noise. Make sure that there are no clumps, so use a stirring rod if necessary. After color change has taken place and the substance is done heating, then reweigh the substance, but be sure to zero out the balance before doing so. Then record weight. Add 20 ml of deionized water to change the substance to bluish green. Then place the aluminum coil wire in the solution fully submerged and occasionally knock off any copper particles on the wire with the glass stirring rod, this will allow the process to be completed quicker. A Buchner funnel was used to filter the water from the copper and then heated until dry. Data: Item | Mass (g) | Evaporating dish | 52.1795 | Evaporating dish + Salt | 53.1904...
Words: 516 - Pages: 3
...States of Matter Gases, liquids and solids are all made up of microscopic particles, but the behaviors of these particles differ in the three phases. The following figure illustrates the microscopic differences. | | | Microscopic view of a gas. | Microscopic view of a liquid. | Microscopic view of a solid. | Note that: * Particles in a: * gas are well separated with no regular arrangement. * liquid are close together with no regular arrangement. * solid are tightly packed, usually in a regular pattern. * Particles in a: * gas vibrate and move freely at high speeds. * liquid vibrate, move about, and slide past each other. * solid vibrate (jiggle) but generally do not move from place to place. Liquids and solids are often referred to as condensed phases because the particles are very close together. The following table summarizes properties of gases, liquids, and solids and identifies the microscopic behavior responsible for each property. Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior | gas | liquid | solid | assumes the shape and volume of its container particles can move past one another | assumes the shape of the part of the container which it occupies particles can move/slide past one another | retains a fixed volume and shape rigid - particles locked into place | compressible lots of free space between particles | not easily compressible little...
Words: 2336 - Pages: 10
...Cp8, Coordination Compound, Synthesis & Product Yield Observation, Description & Questions 1. Compound 1 was initially a light blue color. After adding the oxalic acid and heating it changed to a yellow color. Once the saturated potassium oxalate solution was added it changed to a red color. Once most of the hydrogen peroxide was added it changed colors again to murky brown. Finally it changed to a green color after the solution was brought to a boil and more oxalic acid was added. Compound 3 were crystals that of the same green color. 2. We started with: 10.000 g Fe(NH4)2(SO4)2 • 6 H2O / 392.14 g/mol = .02550 mol. We ended with 6.557 g K3Fe(C2O4)3 • 3 H2O / 491.24 g/mol = .01335 mol. .01335 mol / .02550 mol * 100% = 52.35% yield. 3. If the yield had been greater than 100% percent the likely reason would be that some liquid from the washing process hadn’t been allowed enough time to dry and caused the final weight measurement to be off. 4. Since the yield of the final solid crystals was about half of the starting amount it is likely because the solution didn’t have enough time to completely form into the solid compound. Also, in there may have been a limiting reagent that wasn’t taken into consideration. 5. Charge on iron in reagent I (Fe(NH4)2(SO4)2 • 6 H2O) = 2+ 6. Charge on iron in product III (K3Fe(C2O4)3 • 3 H2O) = 3+ 7. K3Fe(C2O4)3 • 3 H2O = potassium trioxalatoferrate(III)...
Words: 260 - Pages: 2
...eChat Reflection Sheet Name: Brittany Date: October 5th eChat Activity #: 1.3.1 Answer the following questions and submit your summary after attending the eChat: 1.What topics were discussed during this eChat? We began this eChat with a quick look at the calender and important dates that are fast approaching, such as the test. This test will be written on Wednesday, October 21st. We have approximately two weeks to catch up on work and prepare ourselves for the test date. You will be emailing us to confirm we set up a time with our contact teacher for the 21st to write the test. The test is a paper copy and you will be providing us with a formula sheet, periodic table and the polyatomic ion sheet. We are not permitted to bring any materials with us to the written test as everything will be provided. I appreciate the fact that you will be emailing us to let us know which formulas we must study and ensuring that we memorize the prefixes for the covalent compound naming. We reviewed a few examples for balancing equations practice and discussed using the lowest coefficient possible as well as following proper convention for symbols. We moved on to reviewing an example for writing word equations as well as percent composition. During the percent composition you ensured we understand each step must be included for full point in case of an error during our procedure. We finished the eChat reviewing empirical formulas as well molecular formulas and discussing stoichiometry...
Words: 604 - Pages: 3
