Chemistry Class 9 Notes Pdf Download

[Eddie Boyum]

TheFULL COURSE Notes (1st and 2nd Semesters) of General Chemistry Notes is 381 pages in length (Section 1 through Section 20) and covers ALL lecture notes and topics discussed in your ENTIRE general chemistry lecture course.

Science is a subject that explains how the world around us is made and the chemical reactions that make things happen around us. From rust to decomposition, chemical reactions provide a more in-depth insight into how molecular interaction and changes occur. Chapter 1 of CBSE class 10 Science explains how a substance changes form.

Learn more about chemical reactions and equations by exploring CBSE Notes for Class 10 Science Chapter 1. These CBSE notes are comprehensive and detailed yet concise enough to glance through for exam preparations.

A chemical reaction occurs when one or more reactants are changed into one or more products. The constituent atoms of the reactants are rearranged in a chemical reaction, resulting in the formation of various substances as products.

A chemical reaction can be determined with the help of any of the following observations.

a) Evolution of a gas

b) Change in temperature

c) Formation of a precipitate

d) Change in colour

e) Change of state

A chemical reaction is a process that causes one set of chemical components to change into another. Chemical reactions are defined as changes in the locations of electrons in the formation and breaking of chemical bonds between atoms, with no change in the nuclei, and are described using a chemical equation. At a given temperature and chemical concentration, chemical reactions occur at a predictable rate. Reaction speeds often increase as the temperature rises because more thermal energy is available to attain the activation energy required to break bonds between atoms.

A symbol is a chemical code for an element. Each element has a one or two-letter atomic symbol, which is, in most cases, the abbreviated form of its name.

Valency is the combining capacity of an element. It can be considered as the number of electrons lost, gained or shared by an atom when it combines with another atom to form a molecule.

According to the Law of Conservation of Mass, no atoms can be created or destroyed in a chemical reaction, so the number of atoms for each element on the reactants side has to balance the number of atoms that are present on the products side.

In other words, the total mass of the products formed in a chemical reaction is equal to the total mass of the reactants participating in a chemical reaction.

Chemical equations are balanced using coefficients. A coefficient is a numerical value that is added to the front of a chemical symbol or formula. It indicates the number of atoms or molecules of the material involved in the process.

Hit and trial method: While balancing the equation, change the coefficients (the numbers in front of the compound or molecule) so that the number of atoms of each element is the same on each side of the chemical equation.

A single reactant decomposes on the application of heat or light, or electricity to give two or more products.

Types of decomposition reactions:

a. Decomposition reactions which require heat-thermolytic decomposition or thermolysis.

One of the best examples of precipitation reactions is the chemical reaction between potassium chloride and silver nitrate, in which solid silver chloride is precipitated out. This is the insoluble salt formed as a product of the precipitation reaction. The chemical equation for this precipitation reaction is provided below.

A redox reaction occurs when the oxidation states of the substrate change. The loss of electrons or an increase in the oxidation state of a chemical or its atoms is referred to as oxidation. The gain of electrons or a decrease in the oxidation state of a chemical or its atoms is referred to as reduction.

It refers to the oxidation of fats and oils in food that is kept for a long time. It gives foul smell and bad taste to food. Rancid food causes stomach infections during consumption.

Prevention:

(i) Use of air-tight containers

(ii) Packaging with nitrogen

(iii) Refrigeration

(iv) Addition of antioxidants or preservatives

In the electrolysis of water (acidified), the gases that are evolved at the anode and cathode, respectively, are oxygen and hydrogen. Hydrogen ions gain electrons from the cathode and form hydrogen gas, and oxygen ions give electrons to the anode and form oxygen gas.

On the faculty side, Dr. Andrea Cook had a banner first year taking over our organic laboratory enterprise, and we bid farewell to Dr. Claire Besson as she has moved to Binghamton University. We welcomed Dr. Holden Thorp as professor of chemistry and medicine, a name that might be familiar as he is currently the editor-in-Chief of the Science family of journals. We made such a strong impression on him when he gave the prestigious Caress seminar a few years back that he simply had to join our ranks!

The monolith of the Kennedy Center was shimmering in magic light, and the Pentagon had not been attacked yet. The year was 1991, and I was about to start my first semester at GW. My startup funds were $80,000, and an empty 600-foot lab was waiting for me to fill it with compelling new ideas that would attract major funding.

My entire network of professional connections was left behind in Europe, so initially this proved to be a challenge. Based on the number of speaking invitations, the community loved my research, but when it came to funding somehow other proposals got the cigar. The year 1995 brought a breakthrough when a substantial National Science Foundation (NSF) grant was awarded to my lab. Almost a decade later, after a series of single investigator grants of increasing complexity, it was time to target next level opportunities.

In 2004, through a multi-departmental collaboration, we brought the first grant from the W.M. Keck Foundation to GW. Another decade passed by, and in 2014 we managed to raise the stakes by another order of magnitude when a multi-institutional proposal from my lab garnered a Defense Advanced Research Projects Agency (DARPA) award. Overall, during the past 32 years, more than $24 million external funding was awarded to my research. Not a bad return on an $80,000 investment!

Securing funding meant that I had the opportunity to work with a growing number of talented students, postdoctoral associates, research scientists and top-notch external collaborators. Throughout the years we tackled diverse research problems, from creating new tools for ultrasensitive biomedical analysis, to developing methods for the rapid discovery of the mechanism of action of emerging threat agents, to novel methods for molecular imaging of biological tissues, and to single cell metabolomics in biological nitrogen fixation.

Entering a new area was always invigorating because of the new learning opportunities and the exciting collaborations. Our results were disseminated in over 200 peer reviewed publications and protected by 19 issued patents. Some of the created intellectual property was licensed and commercialized by our industrial partners.

However, the most rewarding (and sometimes frustrating) part of all these efforts has always been working with people. Creating and imparting knowledge with students, problem solving with coworkers and contemplating the future of the department with colleagues have been challenging and fulfilling at the same time. As I am writing this farewell missive, I feel thankful to all of you, who participated in this 32-year adventure.

Looking back, I realize none of this would have been possible without the supporting environment, colleagues, and an institution that tolerated my initial ignorance and endured my impatience. Thank you all for three decades of fun and the opportunity to grow together.

Since 2013, the Sadtchenko group, led by Associate Professor of Chemistry Vladislav Sadtchenko, has been on the cutting edge of the development of advanced thermal analysis techniques.

The Sadtchenko group uses ultrafast fast scanning calorimetry (uFSC) to investigate structural and phase transformations in glassy films of molecular materials. The FSC method takes advantage of exceptionally high heating rates, which are millions of times (!) higher than those implied in classical DSC studies. The primary advantage provided by such rapid heating is a proportionally dramatic increase in the sensitivity of the calorimetric measurement, which enables accurate measurements of the heat capacity of molecule films as thin as a few nanometers.

Yet, during FSC experiments, the rapid heating accompanied by a high flux of thermal energy into a film of amorphous material leads to the formation of an unusual type of shock front known as an endothermic rarefaction shock wave, which has been predicted by FKPP theory but has never been observed in solid materials.

The Cahill research group celebrates 23 years at GW! Hard to believe! Professor Cahill remains committed to his chair duties, while the students and postdocs are up to great things. PhD candidate Chris Hossack spent the summer at Idaho National Lab, whereas Dominique Brager and Jordan Herder had fellowships to spend a few months at Lawrence Berkeley National Lab and Pacific Northwest National Lab (respectively). By the time you read this, Ben Walusiak will have defended his PhD and be a postdoc at Los Alamos National Lab. First-year student Liz Decoteau is off to a great start, as is postdoc Adharsh Raghavan. Undergrads are critical to our operations, and Ahan Panchal has been supported on a prestigious Luther Rice Fellowship over the past year. Well done, everyone!

This year is filled with many awards for the Hao Research Group. Dr. Hao received the NSF CAREER Award and Cottrell Scholar Award. Graduate student Ashley Frankenfield received the American Society for Mass Spectrometry (ASMS) Travel Award. Undergraduate student Jamison Shih received the GW Luther Rice Undergraduate Research Fellowship. The group also attended the annual ASMS conference in Houston with six oral and poster presentations.

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