(Solved): 2.3a Word Equations A WORD EQUATION is a representation of a chemical reaction. The REACTANTS are ...

2.3a Word Equations A WORD EQUATION is a representation of a chemical reaction. The REACTANTS are on the left side of the equation. The PRODUCTS are on the right side of the equation. There is an between them that acts like an equals sign. Ex. Law of Conservation of Mass - the total mass of the reactants is ALWAYS equal to the total mass of the products. - Atoms are not created of destroyed in a chemical reaction. They are just Chemical reactions may involve sophisticated chemicals, as in the explosive reaction of dynamite, or simple household materials, as in the reaction of a bathroom cleaner with a stain. They may occur constantly, as in the growth of your body, or occasionally, as in the changing colour of leaves in the fall. How can you describe such a wide range of reactions? For convenience, chemists use a word equation. A word equation is one way of representing a chemical reaction: it tells you what reacts and what is produced. Word equations are an efficient way to describe chemical changes, to help chemists recognize patterns, and to predict the products of a chemical reaction. Writing Word Equations Word equations are written in a particular format. The left side of a word equation lists the names of all the reactants (the substances present initially), and the right side lists the names of all the products (the substances present at the end). An arrow points from the reactants to the products: all the reactants $$?$$ all the products The reactants, as well as the products, are separated by a plus sign $$(t)$$ : reactant $$1+$$ reactant $$2?$$ product $$1+$$ product 2 Word Equations for Some Chemical Reactions You know that the rusting of iron is a slow process - it takes a car a long time to rust. However, when hot steel wool (iron) is plunged into a bottle of oxygen, a spectacular chemical reaction occurs (Figure 1). The reactants are iron and oxygen, and the product is iron(III) oxide. The word equation for this reaction is written as Figure 1 iron $$+$$ oxygen $$?$$ iron(III) oxide Ironillil avide forms whin steel wool are: The reaction that occurs when a coil of copper wire is placed in a beaker of colourless silver nitrate solution is shown in Figure 2 . The word equation for this chemical reaction is copper $$+$$ silver nitrate $$?$$ silver $$+$$ copper(II) nitrate In Chapter 5, you investigated several chemical reactions. These reactions can be described using word equations. For example, when zinc metal is added to a hydrochloric acid solution, a flammable gas and a colourless solution result: $$\text{ zinc + hydrochloric acid }?\text{ hydrogen }+\text{ zinc chloride }$$ Challenge In the chemical test for hydrogen, the gas "pops" as it reacts explosively with oxygen from the air: $$1,2,3$$ What word equations hydrogen $$+$$ oxygen $$?$$ water vapour represent the reactions in your Challenge? A soll of copper is dipped in siver nitrane solution, a fury deposit of silver metal forms on the siolution aiso turns blue as a coppertio nitrate solution forms. Try This Activity Completing Word Equations Themists use word equations to summarize what (c) When aluminum foil is placed in a solution Bcy observe. Copy and complete the word of copper(II) chloride, copper metal and ations that describe the following another solution are formed. cecrvations. aluminum $$+$$ copper(II) chloride $$?$$ a) Aluminum resists corrosion because it reacts copper +? with a gas found in air to form a protective coating of aluminum oxide. (d) When sodium sulfate and calcium chloride aluminum $$+$$ ? $$?$$ aluminum oxide solutions are mixed, a precipitate of calcium sulfate and another substance is formed. 3) Zinc metal, used as a coating in galvanized sodium sulfate $$+$$ calcium chloride $$?$$ iron, also reacts with air to form a coating calcium sulfate +? that resists further corrosion. $$\text{ zinc }+\text{ oxygen }?\text{ ? }$$ Interstanding Concepts 4. Write word equations to represent the following chermical 2. What is the purpose of witing a word equation? reactions: = Gamine the following word equation: (a) Carbon dioxide and water ase produced in human cell propane $$+$$ axygen $$?$$ carbon diowide $$+$$ water respiration. The reactants are sugar and an important gas that humans need to survive. (a) List all the reactants in this reaction. (b) Stalactites form in caves whien calcium bicarbonate 3) List all the products in this reaction. reacts to form calcium carbonate, water, and carbon (c) What is the purpose of the arrow in tho word equation? diaxide gas. 2. Wiate wod equations for the following reactions; Reflecting a) $${\mathrm{CaCl}}_2$$ and $${\mathrm{Na}}_2{\mathrm{SO}}_4$$ react to form $${\mathrm{CaSO}}_4$$ and $$\mathrm{NaCl}$$. 5. Write your cwn word equation for the production of a b) $${\mathrm{BaCO}}_3$$ reacts when heated to produce $$\mathrm{BaD}$$ and $${\mathrm{CO}}_2$$ paanst butter sandwich. (c) $${\mathrm{AgNO}}_2$$ reacts with $$\mathrm{KCl}$$ to produce $$\mathrm{AgCl}$$ and $${\mathrm{KNO}}_2$$. 6. How would you classily the reactions you see in the Try This? In Investigation $$6.2$$, you saw that when two solutions react to form a solid precipitate, the mass stays the same. Is the mass constant for other types of reactions? Are there any reactions where mass is gained or lost? In some chemical reactions, matter may appear to be destroyed. For example, you might think that the burning of a forest destroys matter, reducing the trees to a mere handful of ashes (Figure 1). What happens in a chemical reaction when one or more of the reactants or products is a gas? For more than 200 years, scientists tried to devise methods to trap the gases that were used or produced in reactions, and to find ways to measure their masses. After years of experimenting, scientists agreed that mass is neither gained nor lost in any chemical reaction. This conclusion is stated as a law. A scientific law is a general statement that The biomass in treer secrss to "disapyear" sums up the conclasions of many experiments, or a statement that summarizes an observed pattern in nature. $${\mathrm{ter}}^{?1}\left({\mathrm{H}}_2\mathrm{O}\right)$$, one molecule of carbon dioxide 10.), heat, and light. Understanding Concepts As you can see in Figure 3, all the atoms present 1. State the Law of Conservation of Mass. How is this law beginning of a chemical reaction are present explained in tems of atma? the reaction. Thus, the total mass of the atoms he reactants remains equal to the total mass of 2. When a log bursa in a firs, the oshes here a much lower atoms in the products; the atoms in the mass than the leg. Explain. ztants recombine to form new molecules. 3. (a) Make a tabie with tree colurns and tour rows as Environmental View Law of Conservation of Mass has implications Scyond the laboratory. Think about engines that fuels as a source of energy. When cars burn Wine, energy is released during the chemical tion of combustion. However, sinee mass is srved, all of the mass of the fucl is still present (b) Using Figure 3, court the nunter of atms of esch me form after combustion occurs (Figure 4), twpe in the reactants and record tham in the tocie. Count the number of atmens of aach type in the products and record them in the table. (e) Wavt de your results suggest about the Law of Conservation of Mass? 4. A solis has a mass of 350 . When it is riard with a selution a chemical rebetion occus. If the firal total mass of product is is \&. what wos the mast of the salution? 5. Solutiea $$A$$ has a mass of $$60\mathrm{g}$$. Solution $$B$$ mas a mass of $$40\mathrm{g}$$. When ther are minod, a thenical reastion octurs in which gos is groduced If the mass of the final muxture is $$85\mathrm{g}$$. what mass of pat was producod? 6. Have yee guar neticad that if you weigh yousself immodiatuly befor bod and immediately after gotting up in the narning, rou weigh lass in the mornirg? Does this mean that the Law of Conservation of Mass is not troe? Suggest an explanation for the difference in mass. Wogran of tuel mied with ongen in an internal armbution 7. Wiv dase bread rise when it is bolod? How do you think Froduces 3 to $$4\mathrm{kg}$$ of water vepeur and cabon dionide ans, as the mass of the breod weule compare to the erigine pollutere gases ruch is nisopen oxides and urbumed tocul mass of the ingreditnts in the recipe? Exploring Challenge 8. Ousigh an appantus thet would alow you to compere the mass of reactents with nee mass of products when a doen the Law of Conservation af Mass relate to ynur small anount of wood bums. Wienge? Reflecting 9. How hese your deas about inatter and mass changwo? Did you know that gases had mass? Did you know nat M Work the Web matter could not be creased or deatropedi Write a shart Sat is being done to reduce the amounts of polutants in poragoph desertoing haw your iabas may tove charged. riele oxhausts? Visit wwwscienceraison,com and follow Inks from Science 10, $$6.3$$ to reswarch this issue. A WORD EQUATION is a representation of a chemical reaction. The REACTANTS are on the left side of the equation. The PRODUCTS are on the right side of the equation. There is an accow between them that acts like an equals sign. Ex. Hydrogen $$+$$ Oxygen $$?$$ water Coppert silver nitcate $$?$$ silver+ copper (II)nitcate Law of Conservation of Mass - the total mass of the reactants is ALWAYS equal to the total mass of the products. - Atoms are not created of destroyed in a chemical reaction. They are just rearcanged