1.Chemical ReactionsThis is the fourth text which will be used for practicing dictation andtranslation in the written part of the exam.The key words are emphasized in boldand there is a list of them at the end of the presentation.
2.Chemical Reactions• When a chemical reaction occurs, new substances (called products)form from the substances taking part in the reaction (called reactants).• Burning is an exothermic reaction – more heat is given out duringthe reaction than is taken in.• Oxidation occurs when a substance combines with oxygen.• Reduction occurs when a substance loses oxygen.
3.Chemical Reactions• Reversible chemical reactions can go forwards and backwards. Whenheated, nitrogen dioxide (NO2) breaks down into nitrogen monoxide(NO) and oxygen (O2), when cooled the change is reversed.• Some reactions take in more heat energy than they give out. Thesereactions are called endothermic.• Electron transfer – During the oxidation process, atoms lose electronsand are oxidized. During reduction, atoms gain electrons and arereduced.
4.Chemical Reactions• Each element has a chemical symbol to identify it, and eachcompound a chemical formula. The formula indicates how theelements in the compound are combined. A chemical equation showswhich substances react and the products that result.• An atom’s valency shows the number of chemical bonds it can form.It is the number of electrons the atom gains, loses or shares when itmakes bonds.
5.Chemical Reactions• Controlling reactions – Chemists speed up reactions by making thereacting particles collide with each other more often or with greaterenergy. Substances called catalysts speed up reactions by helpingsubstances react together. They remain unchanged by the chemicalreaction.• Increasing the concentration of a reactant speeds up a reaction.Dyeing a material is faster with a concentrated dye – there are moredye molecules to collide with the material.
6.Chemical Reactions• The surface area of a solid object is the size of its outer surface.Increasing the surface area of a reacting substance speeds up thechemical reaction.• Yeast is a fungus containing enzymes, which are biological catalysts.The enzymes in yeast make starches and sugars break down morerapidly into carbon dioxide and ethanol.
7.Key words:• Product – produkt, proizvod – Reactant - reaktant• Burning – sagorevanje• Reversible/reversed – reverzibilna, povratna• Oxidation/reduction – oksidacija/redukcija• Chemical symbol – hemijski simbol• Chemical formula – hemijska formula• Chemical equation – hemijska jednacina• Chemical bonds – hemijske veze
8.Key words• Catalyst – katalizator• Catalyzation - katalizacija• Dye – boja• Dyeing – bojenje• Surface area – ukupna spoljna povrsina• Yeast – kvasac• Starch – skrob• To break down – razgraditi
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Chemical Reactions Chp 21 ... Why is Lavoisier called the father of modern chemistry? His explanation of the law of conservation of mass started modern science. ... Electroplating puts a coat of metal onto a surface. Electricity is also used to separate aluminum metal from ore. More Energy In In the following endergonic reaction, energy from ...
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Flint Water Supply: Before 2014. Flint’s water was supplied by Detroit. Detroit added phosphate (PO 4. 3-) to the water to precipitate all metal cations.. These solids coat the inside of the pipes creating a passivation layer that protects the pipes from corrosion.
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KS3 Chemistry 7F Simple Chemical Reactions * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 7F Simple Chemical Reactions Word equations Reactions with oxygen Chemical reactions everywhere Summary activities Reactions with acid Contents Physical and chemical changes How many physical and chemical changes can you spot? What is a chemical ...
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Ionic Equations. Molecular Equations: Similar to a typical balanced equation. All species are listed as either molecules or formula units. HCl (aq) + NaOH (aq) H. 2 O (l) + Na Cl (aq)Complete Ionic Equation: Lists all substances as ions. Only if the substance is aqueous and a strong electrolyte
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Chemical reactions can either release energy or absorb energy. A chemical reaction that requires an input of energy is called an endothermic reaction. The energy is absorbed from the surroundings, usually as heat. A chemical reaction in which energy is released to the surroundings is called an exothermic reaction.
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Types of Reactions and Balancing Equations * * A. also known as a “chemical change†B. Indicators of a Chemical Reaction 1. Light production 2. Odor production 3. Heat production/Temperature Change Exothermic - energy is released (produces heat) Endothermic - energy is absorbed (feels cold) 4. Formation of a precipitate (solid) 5.
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Practical work: Perform a thermal decomposition reaction on each of these compounds and state: The colour changes you observed The reaction that happened Copper carbonate: Zinc carbonate: CuCO3 (s) CuO(s) + CO2 (g) (Green – Black) ZnCO3 (s) ZnO(s) + CO2 (g) (White – Yellow) Sulphuric acid has many important uses – car batteries ...
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Copper is not really on the table, but CARBONATES are. Carbonates are INSOLUBLEin water; they form SOLIDcompounds in water. (with some exceptions, like NH. 4 +1)Copper is NOT in group 1, so. Copper (II) carbonate is solid.
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Write the complete chemical equation and identify the type of reaction. 1’s teach 2’s. Molybdenum as a solid reacts with oxygen to produce Molybdenum (VI) Oxide. Calcium carbonate solid breaks down to produce calcium oxide solid and carbon dioxide as a gas
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Predict the products for the following reaction: Cu + S (Hint: copper is +1) Write the balanced equation for the combination reaction that occurs when lithium metal and fluorine gas react. Write the balanced equation for the reaction that occurs when the surface of aluminum metal undergoes a combination reaction with oxygen in the air.
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Write an equation for the precipitation reaction that occurs (if any) when solutions of sodium carbonate Na 2 CO 3 (aq)and copper(II) chloride CuCl 2 (aq)are mixed. 2. Combine the cation from one reactant with the anion from the other.
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Chemical Energy – Energy stored in the chemical bonds of a substance. Chemical reactions always involve energy changes. Making bonds and breaking bonds involve energy changes. Activation Energy. The energy required to break the bonds in the reactants for a chemical reaction to occur.
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