Gizmo Answer Key: Balancing Chemical Equations

Name: Amya Lucero Date: 04-01-2022 Student Exploration: Balancing Chemical Equations Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts inthe orange boxes. Vocabulary: coefficient, combustion, compound, decomposition, double replacement, element, molecule, product, reactant, single replacement, subscript, synthesis Prior Knowledge Questions (Do these BEFORE using the Gizmo .) The scouts are making s’mores out of toasted marshmallows, chocolate, and graham crackers. 1. What is wrong with the image below? In the end, the ingredients don't match the s'mores. For instance,the final image shows that a total of 8 graham crackers, 4marshmallows, and 4 chocolate bars were utilized, as opposed tothe one side's 5 marshmallows, 3 chocolate bars, and 5 grahamcrackers. 2. Assuming a s’more requires two graham crackers, one marshmallow, and one piece of chocolate, how many s’mores could you make with the ingredients shown? Only 2 total s’mores, with 3 marshmallows, 1 chocolate bar, and 1 graham cracker left over. Gizmo Warm-up In a chemical reaction, reactants interact to form products . This process is summarized by a chemical equation. In the Balancing Chemical Equations Gizmo, look at the floating molecules below the initial reaction: H 2 + O 2 H 2 O. 1. How many atoms are in a hydrogen molecule (H 2 )? 2 2. How many atoms are in an oxygen molecule (O 2 )? 2 3. How many hydrogen and oxygen atoms are in a watermolecule (H 2 O)? 2H 10 4. In general, what does a subscript (such as the “2” in H 2 ) tell you about the molecule? Amolecule's atomiccomposition Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

5. A chemical equation is balanced if the number of each type of atom on the left side is equal to the number of each type on the right side. Is this reaction balanced? Not at all, no. There is only one oxygen atom on the right side and two on the left. Activity A: Balancingequations Get the Gizmo ready: ● Check that the Synthesis reaction is selected and that all coefficients are set to one. (The coefficients are the numbers in the boxes.) Introduction: The equation H 2 + O 2 H 2 O is unbalanced because there are two oxygen atoms on the reactants side of the equation, and only one on the products side of the equation. To balance the equation, youcannot change the structure of any of the molecules, but you can change the number of molecules that areused. Question: How are chemical equations balanced? 1. Balance: Turn on Show histograms . The equation is balanced when there are equal numbers of each type of atom represented on each side of the equation. In the Gizmo, use the up and down arrows to adjust thenumbers of hydrogen, oxygen, and water molecules until the equation is balanced. When you are done, turnon Show summary to check your answer. Write the balanced equation here: 2 H 2 + 1 O 2 2 H 2 O 2. Solve: Turn off Show summary . Use the Choose reaction drop down menu to see other equations, and balance them. Check your answers and then write the balanced equations. 2 Al + 6 HCl 2 AlCl 3 + 3 H 2 2 NaCl 2 Na + 1 Cl 2 1 Na 2 S + 2 HCl 2 NaCl + 1 H 2 S 1 CH 4 + 2 O 2 1 CO 2 + 2 H 2 O 3. Practice: Balance the following chemical equations. (These equations are not in the Gizmo.) A. 2 Na + 1 Cl 2 2 NaCl B. 2 Na + 2 H 2 O 2 NaOH + 1 H 2 C. 2 Mg + 1 O 2 2 MgO Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

D. 2 KClO 3 2 KCl + 3 O 2 E. 2 Al + 3 CuO 1 Al 2 O 3 + 3 Cu F. 1 I 2 + 2 Na 2 S 2 O 3 2 NaI + 1 Na 2 S 4 O 6 G. 6 Mg + 1 P 4 2 Mg 3 P 2 Activity B: Classifyingreactions Get the Gizmo ready: ● Turn off Show summary and Show histograms . Introduction: Chemical equations show how compounds and elements react with one another. An element is a substance consisting of one kind of atom, such as aluminum (Al) or oxygen gas (O 2 ). A compound is a substance made of more than one kind of atom, such as water (H 2 O) or table salt (NaCl). Question: How are chemical reactions classified? 1. Match: Most chemical reactions can be classified as one of four types. Using the chemical equations in the Gizmo as a guide, match the following definitions to the type of reaction. B One reactant is broken down into two or more products. A. Synthesis E A fuel combines with oxygen to produce carbon dioxide (CO 2 ) and water (H 2 O). B. Decomposition A Two or more reactants combine to form one product. C. Single replacement D Two compounds react to form two different compounds. D. Double replacement C A compound reacts with an element to form a new compound and adifferent element. E. Combustion 2. Practice : Balance each of the chemical equations below. (Some equations may already be in balance.) In the space to the right, classify the reaction as a synthesis , decomposition , single replacement , double replacement , or combustion . A. 1 AgNO 3 + 1 KCl 1 AgCl + 1 KNO 3 Two replacements B. 1 H 2 O + 1 SO 3 1 H 2 SO 4 Synthesis C. 2 KI + 1 Cl 2 2 KCl + 1 I 2 Single replacement D. 2 NaHCO 3 1 Na 2 CO 3 + 1 H 2 O + 1 CO 2 Decomposition E. 1 Zn + 2 HCl 1 ZnCl 2 + 1 H 2 Single replacement Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

F. 1 BaCl 2 + 1 Na 2 SO 4 1 BaSO 4 + 2 NaCl Two replacements G. 1 C 3 H 8 + 5 O 2 3 CO 2 + 4 H 2 O Combustion H. 2 Al + 3 CuCl 2 2 AlCl 3 + 3 Cu Single replacement Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved