Lesson-1-CHEMICAL-REACTIONS-CHEMICAL-EQUATIONS.pptx

An equation that has equal number of atoms of each element on both the sides of the equation is called a balanced chemical equation, i.e., mass of the reactants is equal to mass of the products.

1. CHEMICAL REACTIONS & CHEMICAL EQUATIONS GENERAL CHEMISTRY 1 PREPARED BY: MS. ULYANN H.NINGAL

2. LEARNING OBJECTIVES At the end of this lesson, you should be able to: Describe the evidences that a chemical reaction has occurred. Identify the types of chemical reactions; and Write equations for chemical reactions and balance the equations.

3. STOICHIOMETRY is the study of the quantitative relationships in substances and their reactions. It involves: The mole and molar mass Percentage composition & Chemical formulas Chemical equations Mass relationships in equations Limiting reactant/reagent

4. CHEMICAL REACTION - is a process in which a chemical substance/s is converted to one or more new substances. CHEMICAL EQUATION - represents/describes chemical reactions. Reactants – are the substances consumed. Products – are the substances formed.

5. EVIDENCES OF CHEMICAL REACTION Change in color Formation of solid Evolution of gas Change in temperature

6. CHEMICAL EQUATION A shorthand notation of describing chemical reactions. NOTATION FOR CHEMICAL EQUATION Arrow ( ) – means “yields” Addition symbol (+) – separates each substance Solid (s), Liquid (l), Gas (g) and Aqueous ( aq ) – states of matter.  

7. NOTATION FOR CHEMICAL EQUATION Arrow ( ) – means “yields” Addition symbol (+) – separates each substance Solid (s), Liquid (l), Gas (g) and Aqueous ( aq ) – states of matter.  

8. TYPES OF CHEMICAL REACTION Synthesis reaction – two or more reactants form a single product. A + B → AB 2NO + O 2 → 2NO 2 Decomposition reaction – a reactant breaks down into two or more products. AB → A + B Li 2 CO 3 → Li 2 O + CO 2

9. TYPES OF CHEMICAL REACTION Single displacement reaction – one element replaces another in a compound. A + BC → AC + B Cu (s) + 2AgNO 3( aq ) → Cu(NO 3 ) 2( aq ) + 2Ag (s) Double replacement reaction – two ionic compounds exchange ions. AB + CD → AD + CB 2KI ( aq ) + Pb (NO 3 ) 2( aq ) → 2KNO 3( aq ) + PbI 2(s)

10. TYPES OF CHEMICAL REACTION Combustion reaction – a hydrocarbon (a compound containing carbon and hydrogen) reacts with oxygen to form carbon dioxide and water. Hydrocarbon + O 2 → CO 2 + H 2 O 2C 2 H 6 + 7O 2 → 4CO 2 + 6H 2 O

11. WRITING AND BALANCING CHEMICAL EQUATION Analyze the chemical reaction. Identify the reactants and the products . Determine how the reactants combine and products form . If given, take note of the states of each substance whether solid, liquid, gas or aqueous.

12. WRITING AND BALANCING CHEMICAL EQUATION After writing the appropriate chemical equation, balance it by modifying the coefficients only . A balanced equation has the same number of atoms of each element on both sides of the equation .

13. WRITING AND BALANCING CHEMICAL EQUATION Take note of this diatomic molecules:

14. WRITING AND BALANCING CHEMICAL EQUATION DIRECTIONS: Write and balance the chemical equation from given chemical reaction. Identify the type of reaction afterwards. EXAMPLE 1: Aluminum metal reacts with iron (II) oxide powder to produce solid aluminum oxide and iron metal.                                 SINGLE DISPLACEMENT

15. WRITING AND BALANCING CHEMICAL EQUATION EXAMPLE 2: Liquid carbon disulfide reacts with oxygen gas to produce carbon dioxide gas and sulfur dioxide gas.                                 SINGLE DISPLACEMENT

16. WRITING AND BALANCING CHEMICAL EQUATION EXAMPLE 3: Mercury (II) oxide decomposes to produce mercury and oxygen.                       DECOMPOSITION

17. AMOUNTS OF REACTANTS AND PRODUCTS

18. OBJECTIVES : Identify mole ratios of reactants and products from balanced chemical equations; Perform stoichiometric calculations related to chemical equations; Explain the relationship of reactants and products in a chemical reaction.  

19. AMOUNTS OF REACTANTS AND PRODUCTS Stoichiometry is the study of the quantities of materials consumed and produced in chemical reactions.

20. 2 slices of bread + 1 hamburger patty → 1 hamburger sandwich Suppose Karen has 14 hamburger patties, how many slices of bread will she need to consume all the patties? The ratio of slices of bread to hamburger patty is 2:1.  

21. 1. Ammonia, NH 3 , is a leading industrial chemical used in the production of agricultural fertilizers and synthetic fibers. It is produced by the reaction of nitrogen and hydrogen gases: 3 H 2 + N 2 → 2 NH 3 The balanced equation says that 3 moles H 2 are stoichiometrically equivalent to 1 mole N 2 and to 2 moles NH 3 . The ratio of moles H 2 to moles NH 3 is 3:2; the ratio of moles N 2 to moles NH 3 is 1:2.

22. a. How many moles of NH 3 will be produced if 10.4 moles H 2 react completely with N 2 ? (moles H 2 → moles NH 3 )   3 H 2 + N 2 → 2 NH 3

23. b. How many moles of N 2 are needed to produce 42.4 moles NH 3 ? (moles NH 3 → moles N 2 ) 3 H 2 + N 2 → 2 NH 3  

24. c. How many grams of NH 3 will be produced from 25.7 moles N 2 ? (moles N 2 → moles NH 3 → g NH 3 ) 3 H 2 + N 2 → 2 NH 3  

25. d. How many grams of NH 3 will be produced if 122 g N 2 reacts completely with H 2 ? (g N 2 → moles N 2 → moles NH 3 → g NH 3 ) 3 H 2 + N 2 → 2 NH 3  

26. 2. Solid lithium hydroxide is used to remove carbon dioxide and is called a CO 2 scrubber. This technique has been used for space vehicles. 2 LiOH + CO 2 → Li 2 CO 3 + H 2 O

27. How many grams of CO2 can be absorbed by 785.0 g LiOH ? (grams LiOH → moles LiOH → moles CO 2 → grams CO 2 ) 2 LiOH + CO 2 → Li 2 CO 3 + H 2 O  

28. Next Lesson: Mass Relationships in Chemical Reactions ( Limiting and Excess Reagent, Theoretical Yield, Actual Yield, Percent Yield )

29. THANK YOU!!