World Journal of Chemical Education, 2017, Vol. 5, No. 1, 12-19 Available online at http://pubs.sciepub.com/wjce/5/1/3 ©Science and Education Publishing DOI:10.12691/wjce-5-1-3 Training Skills to Solve Some Inorganic Chemistry Exercises by Using the Graphic Method of Calculation for Teaching Chemistry in High School C.C. Giac 1,* , N.T.P. Lien 2 , P.N. Tuan 3 1 Faculty of Chemistry, Vinh University, Vinh, Vietnam 2 Faculty of Environmental Science, Saigon University, Ho Chi Minh City, Vietnam 3 Nguyen Thi Minh Khai High School, Ho Chi Minh City, Vietnam *Corresponding author: giaccc@vinhuni.edu.vn Abstract This paper introduces the way to solve some inorganic chemistry exercises by using the graphic method of calculation for teaching chemistry in high school. We have divided them into 7 types of exercise involving in the use of graphs to find the solution methods. Based on these ways, the authors have built 9 Sample Problems. On that basis, the authors compiled 15 drilling exercises for Test Yourself which are used for teaching and self-studying inorganic chemistry in High School. Keywords: inorganic chemistry, graphic method, acids / bases, gases, aqueous solution chemistry, precipitation Cite This Article: C.C. Giac, N.T.P. Lien, and P.N. Tuan, “Training Skills to Solve Some Inorganic Chemistry Exercises by Using the Graphic Method of Calculation for Teaching Chemistry in High School.” World Journal of Chemical Education, vol. 5, no. 1 (2017): 12-19. doi: 10.12691/wjce-5-1-3. 1. Introduction Chemistry exercises play an important role, including content and chemistry teaching methods in high school. Training skills to solve problems is indispensable in chemistry teaching activities. Within the scope of this paper, we will introduce some types of inorganic chemistry exercises that use graphs to infer solution methods. Thereby, training and enhancing skills to solve chemistry exercises in general and inorganic chemistry in particular is very important for students [1,2,3]. 2. Content 2.1. General Problem In inorganic chemistry, a common problem is ( ) ( ) , . . + → ↓ A a gas solid or soln B soln P (The symbol P↓ stands for “precipitate” in solution). The precipitate P can be soluble in an excess reactant of A or B. At that time the same amount of precipitate can have two different values of A or B. To solve this problems, teacher can guide students to use the graph of the relationship between the number of moles of precipitate P ( n ↓ ) and the number of moles of A or B [4,5]. 2.2. Some Common Types 2.2.1. Type 1: Bubble Slowly the Gas of CO 2 or SO 2 through Solution of Ca(OH) 2 or Ba(OH) 2 → P↓ ex ess 2 CO c → Soluble In this case CO 2 will perform 2 tasks below. Task 1: Increase gradually the mass of precipitate up to a maximum, according to the reaction ( ) ( )( ) () () 2 3 2 2 CO g Ca OH aq CaCO s HO . l + → + (1) Task 2: Dissolve the precipitate, according to the reaction () ( ) () ( ) ( ) 3 2 2 3 2 CaCO s CO g HO Ca HCO aq . l + + → (2) The relationship between the number of moles of CO 2 and the number of moles of precipitate is represented as the graph in Figure 1. a a CO 2 n 0 n Task 1 Task 2 Figure 1.