Balancing Chemical Equations Free Essays

Balancing chemical equations 1. Complete the following sentences, using the words or groups of words in the box below. You may use some words more than once. We will write a custom essay sample on Balancing Chemical Equations or any similar topic only for you Order Now †¢ as small as possible |†¢ decrease |†¢ molecules |†¢ quantities | |†¢ balance |†¢ different |†¢ nature |†¢ rearranging | |†¢ bonds |†¢ equal |†¢ never |†¢ release of a gas | |†¢ characteristic properties |†¢ heat |†¢ new elements |†¢ rules | |†¢ check |†¢ increase |†¢ nuclear |†¢ signs | |†¢ chemical |†¢ law of conservation |†¢ nucleus |†¢ state | |†¢ chemical equation |of mass |†¢ physical |†¢ stoichiometry | |†¢ coefficient |†¢ mass of products |†¢ precipitate |†¢ subscript symbols | |†¢ colour |†¢ mass of reactants |†¢ products |†¢ transformed | |†¢ counting |†¢ molar mass |†¢ proportions |†¢ whole numbers | a)There are three types of changes in matter: ________________________ changes, chemical changes and ________________________ changes. b)A physical change occurs when the form or th e ________________________ of a substance is changed. For example, when liquid water is cooled, it becomes ice. Whether water is in liquid form or in the form of ice, the ________________________ that form water remain the same. The ________________________ of water do not change. c)A ________________________ change alters the ________________________ of a substance. The very nature of the ________________________ is altered: they are no longer the same after the change. This transformation involves ________________________ the bonds between the atoms and forming new molecules. d)A ________________________ transformation involves changes that occur in the ________________________ of the atom. The transformation causes the atoms to split and form ________________________. ) Chemical changes occur when the ________________________ between reactants (initial substances) are broken to form new ________________________ (final substances), whose characteristic properties are ________________________. During this process, the quantities of reactants ________________________, and the quantities of pro ducts ________________________. f) We can recognize that a chemical change has taken place by certain ________________________: the ________________________, the emission or absorption of ________________________, the emission of light, a change in ________________________, and the formation of a ________________________. ) A chemical change, or chemical reaction, can be represented by a ________________________, which shows how the change took place. It is useful to identify the ________________________ of the substances (solid, liquid, gas or aqueous solution) with ________________________ in parentheses to the right of the substance. h) The scientist Antoine Laurent de Lavoisier made this famous statement that explains the________________________: â€Å"Nothing is lost; nothing is created; everthing is ________________________. † This means that the ________________________ before the chemical reaction is equal to the ________________________ after the reaction. ) To follo w the law of conservation of mass, we must ________________________ chemical equations by ________________________ the number of atoms of each element on the reactants side and on the products side of the equation. The appropriate ________________________ must be placed in front of each substance so that the number of atoms on each side of the equation is ________________________. j) Certain ________________________ must be followed when balancing a chemical equation. The coefficients must be ________________________, and they must be ________________________. New substances must ________________________ be added, nor existing substances removed. Subscripts in chemical formulas must ________________________ be changed. Finally, we must ________________________ the equation by comparing the number of atoms of each element on either side. k) When a chemical equation is properly balanced, we can find the ________________________ of reactants needed for a reaction and predict the resulting quantities of products. ________________________ is the study of these proportions. It is essential to maintain the ________________________ of the substances throughout the reaction. We can use ________________________ to convert moles into grams. 2. What kind of change is described by each of the following examples? |a) a worn tire | | | |b) limewater that turns white | | | |c) a bracelet that tarnishes | | | |d) the fission of a uranium nucleus | | | |e) rusting iron | | | |f) mercury that expands in hot weather | | | |g) the fusion of the nuclei of several atoms | | | |h) food being transformed into energy | | | |i) salt dissolving in water | | | |j) radium emitting radiation | | 3. For each of the following examples, name at least one sign that a chemical change is occurring. a) A match burns. | | | b) A yellow substance appears when NaI is mixed with Pb(NO3)2. | | | c) Bubbles form when chalk is mixed with hydrochloric acid. | | | d) A bright light appears when a piece of magnesium is burned. | | 4. Write a chemical formula to represent the following situation. Aluminum oxide (AlO), commonly called alumina, is formed by the reaction between aluminum (Al) and oxygen (O2). Balance the equation. | | | | | | 5. Balance each of the following chemical equations by indicating the number of atoms in each molecule involved in the reaction. a) C(s)+ H2(g) + O2(g) ( CH3OH(g) | | | | | | | | | | | | | | | | | | | | | b)Al(s) + O2 (g) ( Al2O3(s) | | | | | | | | | | | | | | | | | | | | | c)C(s) + Cl2(g) + H2(g) ( CHCl3(g) | | | | | | | | | | | | | | | | | 6. The decomposition of 10 g of copper oxide is represented by the following equation: 2 CuO(s) ( 2 Cu(s) + O2(g) If you obtain 8 g of copper, what amount of oxygen was released? Explain your answer. | | | | | | | | | | | | 7. Calculate the mass and the number of moles of silver produced if you make 10  mol of zinc react with sufficient silver nitrate. (The equation is not balanced. Zn(s) + AgNO3(aq) ( Ag(s) + Zn(NO3)2 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 8. What mass of glucose will be formed if you make 32  mol of hydrochloric acid react with sufficient carbon? (The equation is not balanced. ) HCl(l) + C(s) ( C10H16(aq) + Cl2(g) | | | | | | | | | | | | | | | | | | | | | | | | | 9. Given the reaction for the synthesis of ammonia: N2(g) + 3 H2(g) ( 2 NH3(g) How many moles of hydrogen are needed to produce 50  g of ammonia? | | | | | | | | | | | | | | | 10. Given the following equation: 2 Na(s) + 2 H2O(l) ( 2 NaOH(aq) + H2(g) How many moles of hydrogen will be produced by the complete reaction of 75  g of sodium? | | | | | | | | | | | | | | | | | ———————– Support activities – Second Year of Secondary Cycle Two |EST | | student BOOK: Chapter 4, pages 108–113 | | Related Handout: Concept review 15 | ACTIVITY 15 EST EST EST EST EST ———————–  ©ERPI Reproduction and adaptation permitted solely for classroom use with Observatory. Observatory / Guide 11129-B How to cite Balancing Chemical Equations, Papers