Writing Word, Formula, and Balanced Chemical Equations

Writing Word, Formula, and Balanced Chemical Equations 

Solid zinc reacts with hydrochloric acid to form aqueous zinc chloride and hydrogen gas. 

Write word, formula, and balanced chemical equations for each of the following reactions  

Solid calcium metal reacts with water to form aqueous calcium hydroxide and hydrogen gas. Write a balanced chemical equation for this reaction. 

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The first step in writing a complete and balanced equation for a chemical reaction is to write correct formulas for the reactants and products. To help us as we learn, we might write the equation in words and later write the formulas. Correct formulas cannot be changed to make an equation balance Only after the correct formulas have been written can we go on to the next step. Then, we use coefficients to change the numbers of formula units to get the same number of atoms of each element on the two sides of the equation. 

You can then use your knowledge of elemental symbols (Lesson 3-2), writing chemical formulas (Lesson 5-2), and balancing chemical reactions (Lesson 6-1) to turn the word equation into a balanced chemical reaction. 

You are given the word equation for the reaction between barium nitrate and sodium carbonate. You must determine the chemical formulas and relative amounts of all reactants and products to write the balanced chemical equation. To write the complete ionic equation, you need to show the ionic states of the reactants and products. By crossing out the spectator ions from the complete ionic equation, you can write the net ionic equation. The net ionic equation will include fewer substances than the other equations. 

Sample Problem A Write word and formula equations for the chemical reaction that occurs when solid sodium oxide is added to water at room temperature and forms sodium hydroxide (dissolved in the water). Include symbols for physical states in the formula equation. Then balance the formula equation to give a balanced chemical equation. 

You know that symbols represent elements, and formulas represent compounds. In the same way, equations are used to represent chemical reactions. A correctly written chemical equation shows the chemical formulas and relative amounts of all reactants and products. Constructing a chemical equation usually begins with writing a word equation. This word equation contains the names of the reactants and of the products separated by an arrow. The arrow means forms or produces. Then, the chemical formulas are substituted for the names. Finally, the equation is balanced so that it obeys the law of conservation of mass. The numbers of atoms of each element must be the same on both sides of the arrow. 

Furthermore, the program has to interpret chemical formulas. For example if the student types "NH3OH" for the formula of ammonium hydroxide he should be told that the hydrogen is incorrect and not that he has misspelled a word. The routine F.QTJUDG was written to interpret any chemical equation. The routine controls the balancing of mass and charge in chemical equations and checks other rules for writing chemical equations, e.g. 

Rewrite the following word equation using chemical formulas. Balance the equation and write the balanced equation in net ionic form ... 

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