Premium Essay

Chemistry Reactions

In:

Submitted By edunn39
Words 1091
Pages 5
Buffer solutions and common ion effect

A buffer solution resists (or buffers) a change in its pH. That is, we can add a small amount of an acid or base to a buffer solution and the pH will change very little.

How to calculate pH of buffer solution containing both acid and conjugate base? Dissociation constant definition 1.1 can be rearranged into
[pic]
or
[pic]
(note that due to sign change [A-] was moved to nominator).
This is so called Henderson-Hasselbalch equation (or buffer equation). It can be used for pH calculation of solution containing pair of acid and conjugate base - like HA/A-, HA-/A2- or B+/BOH. For solutions of weak bases sometimes it s more convenient to use equation in the form
[pic]15.3

Two common types of buffer solutions are :

(1) a weak acid together with a salt of the same acid with a strong base. These are called Acid buffers e.g. CH3COOH + CH3COONa.

(2) a weak base and its salt with a strong acid. These are called Basic buffers. e.g.NH4OH + NH4Cl.

Let us illustrate buffer action by taking example of a common buffer system consisting of solution of acetic acid and sodium acetate (CH3COOH/CH3COONa).
CH3COOH --- H+ + CH3COO–
CH3COONa ---- Na+ + CH3COO-

since the salt is completely ionised, it provides the common ions CH3COO– in excess. The common ion effect suppresses the ionisation of acetic acid. This reduces the concentration of H+ ions which means that pH of the solution is raised. Thus, a 0.1 M acetic acid solution has a pH of 2.87 but a solution of 0.1 M acetic acid and 0.1 M sodium acetate has a pH of 4.74. Thus 4.74 is the pH of the buffer. On addition of 0.01 mole NaOH the pH changes from 4.74 to 4.83, while on the addition of 0.01 mole HCl the pH changes from 4.74 to 4.66. Obviously the buffer solution maintains fairly constant pH and the changes in pH could be described as marginal.

Buffer Action:

A

Similar Documents

Premium Essay

Chemistry Rates of Reaction

...Investigating Rates of Reaction between Hydrochloric Acid and Magnesium Introduction What is Rate of Reaction? The reaction rate or rate of reaction for a reactant or product in a particular reaction is intuitively defined as how fast a reaction takes place. For example, the oxidation of iron under the atmosphere is a slow reaction which can take many years, but the combustion of butane in a fire is a reaction that takes place in fractions of a second. In this case how fast Magnesium reacts with Hydrochloric Acid. The equation for the reaction is magnesium + hydrochloric acid magnesium chloride + hydrogen Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) This is the equation for the reaction which will occur during my experiment What am I investigating? I am investigating the rate of reaction when the concentration of hydrochloric acid is increased with magnesium. What I am expecting is when the concentration increases so to will the speed of the reaction backing up the collision theory. This will be timed and put into seconds on how fast I gather an amount of gas and from my results a graph will show this data. Method To measure how long it takes to gather the amount of gas I had to carefully measure out 50ml of Hydrochloric Acid in a measuring cylinder. I kept this the same throughout all of the experiments in order for a fair test. I then poured this into the conical flask. After this I folded the 10cm...

Words: 1624 - Pages: 7

Premium Essay

Chemistry Rates of Reaction Coursework

...GCSE Chemistry Coursework : Rates of Reaction Chemistry Table of Contents Table of Contents 1 Strand Sa 2 The Science 2 Variables 2 Temperature 2 Concentration 2 My Prediction 3 Strand Sb 3 Risk Assessment. 3 Preliminary Equipment 4 Preliminary Method 6 Strand C 7 Preliminary Data 7 Main Method 8 Main Results. 9 Strand Ea 9 Problems Encountered when collecting data. 9 Alternate Methods 10 Light Meter 10 Gas Collection 10 Strand Eb 11 Data Analysis 11 Graph Evaluation 11 Strand Ra 12 Secondary Data 1 12 Secondary Data 2 13 Secondary Data 3 14 Strand Rb 15 Conclusion 15 Bibliography 16 Strand Sa The Science In the experiment, I will be testing how increasing the concentration of the reactant affects the rate of reaction between hydrochloric acid and sodium thiosulfate .Due to Max Trautz’s collision theory, which states that the higher the concentration of the reactant raises the number of collisions, I predict that the less dilute sodium thiosulfate solution will have a higher reaction rate than that of a lower concentration of sodium thiosulfate. The formula for the reaction is: HCl(aq) + Na2S2O3(aq) NaCl(aq) + SO2(g) + S(s) + H2O(l). The formula shows us that the sulphur precipitate is formed along with water, sodium chloride and sulphur dioxide. Sulphur dioxide is a poisonous gas and so extra care will be taken not to inhale any. Figure 1 [18] Variables The Variables that affect the reaction rate of...

Words: 5307 - Pages: 22

Premium Essay

Rates of Reaction Chemistry Coursework

...Introduction. This is an experiment to investigate into the rate of reaction between sodium thiosulfate (Na2S2O3) and dilute hydrochloric acid (HCl). The formula for this reaction is: Na2S2O3 (aq) + 2HCl (aq) 2NaCl (aq) + S(s) + SO2 (g) + H2O (l). This makes the products Sodium Chloride, Sulphur Dioxide, Sulphur and water Rate of reaction is the speed at which a chemical reaction takes place. Some reaction can take less than a second and other can take over millions of years. During a reaction, we can measure the rate of reaction. The rate of reactions depends on the types of molecules that are combining. There is another thing in rates of reaction called the collision theory. Substances in the liquid, aqueous and gaseous phase consist of particles in rapid and constant motion. The rate of a chemical reaction depends on three factors; the first is - Collision Frequency If a chemical reaction is to happen between two particles, they must first collide. The number of collisions between particles per unit time is known as the collision frequency of the system. This then can be altered by changing the concentration of reactants, total pressure, temperature or the size of the reacting particles. These are all the factors in general that have distinct effects on rates of reaction. The second factor in the collision theory is -Collision Energy Not all collisions result in chemical reactions. Most of the time the colliding particles just bounce off each other. These...

Words: 1504 - Pages: 7

Premium Essay

How Do Organisms Make Up Thermodynamics?

...Biology and chemistry are complimentary to each other; one cannot be studied in its entirety without the firm understanding of the other. Interactions between chemicals are what make up biological life, which makes up organisms. Organisms are living structures made up of cells that consist of animals, plants, and bacteria. They are biologically engineered yet composed of a multitude of chemical reactions. By examining organisms, their premise of living is based off of their ability to create energy. Chemistry is vital to the understanding of biology as seen with the chemical interactions that make up thermodynamics. Thermodynamics pertains to the change in energy and heat that occurs in all of matter. It is divided into categories of isolated...

Words: 695 - Pages: 3

Free Essay

Chemistry of a Cheeseburger

...The Chemistry behind a Cheeseburger The first cheeseburger was created between 1924 and 1926 by a 16 year old chef from Pasadena, California named Lionel Sternberger. The anecdote goes that a passing homeless man suggested Sternberger should add a slice of cheese to his hamburger order. Sternberger then added this to his main menu at the Rite Spot and the cheeseburger was born.1 Today the cheeseburger is marketed by not only fast food chains like Steak-N-Shake and McDonald’s but also steakhouses such as Longhorn and Logan’s Roadhouse. Whether you choose to cook your cheeseburgers at home on the grill or grab one on the go, cheeseburgers are an American tradition that everyone can enjoy. However, not all who devour this scrumptious piece of American history actually know the chemistry behind the ingredients that come together to make this delicious masterpiece. A cheeseburger would not exist without the bun to hold all of the ingredients together. The bun is made of flour, a starch or long chains of sugars molecules known as polysaccharides, yeast, salt and water. Flour, or grains are comprised mainly of wheat. When these ingredients mix, the flour gums up and absorbs all the water to produce a protein matrix called gluten. Gluten is elastic and holds the bread together to give it structure. As you knead the dough, the yeast, a living single cell creature, begins to eat the starch. When the starch is consumed by the yeast, carbon dioxide is produced. The process of microbes...

Words: 1952 - Pages: 8

Free Essay

Alchemy -the Predecessor of Modern Chemistry

...There are many ways to examine the subject of alchemy, including alchemy as a source of symbolism, psychology, and mysticism. It has also been an influence on the world view of various writers, artist, and musicians. The focus of this report is alchemy as a pre-chemistry, which gave a new impulse towards the preparation of medicinal remedies and also was a major influence on today's scientific investigations. Alchemy is an ancient art, practiced in the Middle Ages. The fundamental concept of alchemy stemmed from Aristotle's doctrine that all things tend to reach perfection. Because other metals were thought to be less perfect than gold, it was reasonable to believe that nature created gold out of other metals found deep within the earth and that a skilled artisan could duplicate this process. It was said that once someone was able to change, or transmute a "base" chemical into the perfect metal, gold, they would have achieved eternal life and salvation. In this way, alchemy turned into not only a scientific quest, but a spiritual quest as well. Although the purposes and techniques were often times ritualistic and fanciful, alchemy was in many ways the predecessor of modern science, especially the science of chemistry. The birthplace of alchemy was ancient Egypt, where, in Alexandria, it began to flourish during the Hellenistic period. Also at that time, a school of alchemy was developing in China. The writings of some Greek philosophers may be considered to be among the very...

Words: 665 - Pages: 3

Premium Essay

Branches of Chemistry

...Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of laws and concepts of physics. * Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how different experimental conditions can influence the speed of a chemical reaction and yield information about thereaction's mechanism and transition states, as well as the construction of mathematical models that can describe the characteristics of a chemical reaction. * Chemical physics is a subdiscipline of chemistry and physics that investigates physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics; it is the branch of physics that studies chemical processes from the point of view of physics. * Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (theelectrode: a metal or a semiconductor) and an ionic conductor (the electrolyte). * Femtochemistry is the area of physical chemistry that studies chemical reactions on extremely short timescales, approximately 10–15 seconds (one femtosecond, hence the name). The steps in some reactions occur in the femtosecond timescale and sometimes in attosecond timescales,[1] and will sometimes form intermediate products. * Geochemistry is the science that uses the tools and principles...

Words: 1073 - Pages: 5

Free Essay

Cyclohexene Lab Report

...Lab Report Chemistry 341L: Preparation of Cyclohexene Introduction: The purpose of this lab was to prepare an alkene, cyclohexene, by the dehydration of an alcohol, cyclohexanol. In this experiment cyclohexanol is dehydrated to prepare cyclohexene, using phosphoric acid as a catalyst. Unsaturation tests are then done to ensure cyclohexene was prepared. Experimental Scheme: The procedure for the Preparation of Cyclohexene lab started with first having to add 10mL of cylcohexanol (clear liquid with strong odor), and 2.5mL of phosphoric acid (clear liquid) to a 50-mL round bottom flask. These liquids were mixed together well; a boiling stone was added to the flask in order to allow for a smoother and gentle boil. Below is the equation for the reaction that took place in this lab. Equation 1: Formation of the product cyclohexene, from the reactant cyclohexanol with the aid of a catalyst phosphoric acid4 Next a distillation apparatus had to be assembled, using a 25-mL round bottom flask as a receiving flask, this flask was then placed into a beaker of ice water refer to figure 1. Figure 1: Distillation apparatus5 Distillation is used in order to dehydrate the cyclohexanol. After the apparatus was assembled we circulated the cooling water in the condenser, while heating the mixture in the flask. The flask was heated until the product started to distill, and collect into the receiving flask in the ice water bath. We continued to heat the mixture...

Words: 1724 - Pages: 7

Premium Essay

Chemistry Chapter 01

...Introductory Chemistry Introduction Instructor: Dr. Tao Tao Course Section: CHEM1405.6013-6014 Meeting Time: TTh 6:00pm-9:10pm Bldg 13-629 Office Hours: TTh 5:30 pm-6:00 pm Contact: tao.tao@lonestar.edu Introductory Chemistry 2 Course Material Requirements • Textbook – Introductory Chemistry, by Nivaldo J. Tro 5th edition • Chapters 1-4, 6-10, 14 • Sections, 5.6-5.10, 12.4-12.8, 13.6-13.8 • Scientific Non-programmable Calculator • Safety Goggles for Lab • Lab Coat/Apron (Optional) Introductory Chemistry 3 Evaluation and Grade • Tests: 45%; 4 tests, best of 3, no make-up unless good excuses (documented, in advance notice) • Open-book Quizzes: 10%; best n-2, no make-up • Laboratory: 25% • Final Exam: 20% • Homework: Encouraged but not mandatory • Problem Set: Provides but not mandatory • Final withdrawal day: Nov. 10th, 2014 Introductory Chemistry 4 Lab Report/Grade Guideline • Pre-lab write-up (30%): Complete before lab starts, will be checked and signed for completeness – – – – Title/Date Aim/Purpose Introduction Procedures • Lab Performance and Quality of data (25%): will be checked and signed when leaving lab – Observations – Collect and record data • Post-lab (40%) – Result (Calculations, Graphs, Interpretations etc), – Discussions/Conclusions – Post-lab questions if any • Overall Report Neatness (5%) • Report due one week after the completion of experiment for full credit; after two weeks, no report will be accepted, and no credit...

Words: 2071 - Pages: 9

Free Essay

Phenylalanine

...Phenylalanine is a critical and required amino acid for the normal biological productions of proteins. The body requires a certain amount of phenylalanine because it does not produce it naturally. The human body obtains Phenylalanine thru proper diet. Thru the biological process of protein formation the body converts phenylalanine into tyrosine, which is essential to form required chemicals and proteins that the body needs to functions normally. Deficiency of phenylalanine causes numerous healthy problems such as altered state of mind, lack of energy, memory issues, confusion, and decreased alertness. High blood levels of phenylalanine can also be bad. High levels of phenylalanine can lower intelligence, causes anxiety and depression, and the inability to focus or pay attention. This is why phenylalanine is such an important molecule. Too much of it can cause problems and a deficiency also causes health problems, therefore it is important to be educated about it. The IUPAC name for phenylalanine is (2S)-2-Amino-3-Phenylpropanoic Acid. There are also common names of phenyalanine, L-Phenyalanine and D-Phenylalanine. Phenylalanine is a nonpolar hydrophobic molecule, which is why it is buried inside proteins. Phenylalanine is an aromatic compound with a melting point of 283 degrees Celsius. It has a solubility of 26.9 grams per mole. The structural formula can be seen on the cover page and it’s molecular formula is C9H11NO2. Phenylalanine is found in protein. It is...

Words: 652 - Pages: 3

Premium Essay

Dcdcdz

..._____________________________________________________________________CHEM 100 LECTURE UNIT 1. FOUNDATIONS OF CHEMSITRY Chemistry is the study of matter and the changes it undergoes. Matter is anything that occupies space and has mass. Applications of Chemistry • Energy and the Environment • Fossil fuels • Solar energy • Nuclear energy Health and Medicine • Sanitation systems • Surgery with anesthesia • Vaccines and antibiotics Materials and Technology • Polymers, ceramics, liquid crystals • Room-temperature superconductors? • Molecular computing? Food and Agriculture • Genetically modified crops • “Natural” pesticides • Specialized fertilizers • • • Classification of Matter A substance is a form of matter that has a definite composition and distinct properties. An element is a substance that is composed of tiny particles called atoms. A compound is a substance composed of atoms of two or more elements chemically united in fixed proportions. Compounds can only be separated into their pure components (elements) by chemical means. A mixture is a combination of two or more substances in which the substances retain their distinct identities. Physical means can be used to separate a mixture into its pure components. Homogenous mixture – composition of the mixture is the same throughout. Heterogeneous mixture – composition is not uniform throughout. 1 |P a g e _____________________________________________________________________CHEM 100 LECTURE PROPERTIES OF MATTER...

Words: 495 - Pages: 2

Premium Essay

The Science Behind Messaging: The Chemistry Of Aging

...THE CHEMISTRY OF AGING Thesis statement: The science behind aging includes both biological and chemical factors. The Oxidative Damage Theory and Free Radical Theory are two important theories that theorize why organisms age. Researchers have done experiments that discovered chemicals that speed up or slow down aging. A. Introduction 1. Topic sentence: Has anyone ever wondered why we age? Is it because of religious reasons, or are we genetically engineered to do so, or does the everyday changing world affect how we age. 2. The definition of aging and what humans characterize aging by. 3. How the chemistry of the human body leads to the biological changes which causes humans to age. B. Scientists base their theories off of others and have found...

Words: 841 - Pages: 4

Free Essay

Physics

...size: 12) Reading assign. Measurement Diff. system of measurement fundamentals and derive quantities scientific notation rules in significant figures conversion of units http://www.hep.man.ac.uk/babarph/babarphysics/physicists.html ) I.1 Science The intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment. I.2 The Branches of Science The Physical Sciences * Physics: The study of matter and energy and the interactions between them. Physicists study such subjects as gravity, light, and time. Albert Einstein, a famous physicist, developed the Theory of Relativity. * Chemistry: The science that deals with the composition, properties, reactions, and the structure of matter. The chemist Louis Pasteur, for example, discovered pasteurization, which is the process of heating liquids such as milk and orange juice to kill harmful germs. * Astronomy: The study of the universe beyond the Earth's atmosphere. The Earth Sciences * Geology: The science of the origin, history, and structure of the Earth, and the physical, chemical, and biological changes that it has experienced or is experiencing. * Oceanography: The exploration and study of the ocean. * Paleontology: The science of the forms of life that existed in prehistoric or geologic periods. * Meteorology: The science that deals with the atmosphere and its phenomena, such as weather...

Words: 1431 - Pages: 6

Free Essay

Chemistry Review

...Chapter 1 1. Analytical Chemistry- study that focuses on the composition of matter Physical Chemistry- Area that deals with the mechanism, rate, and energy transfer that occurs when matter undergoes a change Biochemistry- study of the process that take place in living organisms Organic Chemistry- study of all chemicals containing carbon Inorganic Chemistry-study of chemicals that do not contain carbon 2. A Teory is a well tested explanation, but a hypothesis is a well educated guess 3. Dependent Variable 4. Independent Variable Chapter 2 1. Intensive depends on the type of matter in a sample, but extensive depends on the amount of matter 2. Extensive 3. Mass- measure of amount of matter the object contains 4. Volume- measure of amount of space occupied by an object 5. Liquid- indefinite shape, yet fixed volume Gas- takes shape and volume of container Solid- definite shape and volume 6. Gases exist in the gases state at room temperature, vapor describe the gaseous state that is generally a liquid or solid at room temperature 7. Physical change- some properties of a material change, but the composition of the material doesn’t 8. Mixture- a physical blend of two or more components 9. Homo-Composition uniform throughout Hetero-not uniform 10. Solution- homogeneous mixture 11. Filtration and distillation 12. water to gas, back to water 13. Element- simplest form of matter that has a unique set of properties -Compound- a substance...

Words: 425 - Pages: 2

Premium Essay

Document

...Welcome to CH 125 Inorganic Chemistry for Microbiology Course Description  This course covers inorganic reactions and phenomenon present in microbiological systems. The chemistry of the predominant biological elements of groups I to VII will be discussed. The students will explore the principles of inorganic chemical phenomenon including partially soluble substances, weak acids and bases, buffer systems and redox reactions. In addition, a basic understanding of the chemistry of the biologically important elements (H, C, N, O, K, Na, Ca, Mg, P, S, Cl and some transitional elements) will be explored.    Course Learning Outcomes  Upon successful completion, students will be able to: • Predict cation and anion concentrations of partially soluble solids dissolved in pure water and in a solution containing a common ion. • Apply knowledge of acids and bases in order to predict the pH of a solution containing a weak acid or base. • Demonstrate the use of common pH and redox indicators in microbiological media. • Select appropriate reagents to make a buffer having a desired pH. • Determine which compounds undergo the process of reduction and which undergo the process of oxidation. • Describe the basic chemistry of the predominant biologically important elements and their function(s) in microbiological systems. Dr. Andrew Baer Office Hours Monday: 10:30 am – 11:20 am Wednesday: 1:30 pm – 2:20 pm Thursday: 9:30 am – 10:20 am or by appointment Email:...

Words: 1551 - Pages: 7