Bell work 1/31/17 True or False: In a chemical equation, everything to the right of the arrow is the reactant. Justify your answer

Success Criteria: I can IDENTIFY the common outcome of all chemical changes. I can CLASSIFY common substances as elements or compounds based on their symbols or formulas. I can INTERPRET the results of an investigation to determine whether a physical or chemical change has occurred. I can IDENTIFY the reactants and products of a chemical equation. I can RECOGNIZE that in a chemical reaction the mass of the reactants is EQUAL to the mass of the products (LAW OF CONSERVATION OF MASS).

Study guide answers What is an element? A substance that can not be separated or broken down into simpler substances by chemical means. What is a chemical symbol? a shorter way to write an element’s name. What is a chemical formula? an easier way to write a molecule or compound What is a chemical equation? an easier and shorter way to write a chemical reaction. What is a reactant? what you start with in a reaction What is a product? what you end with in a reaction

Study guide answers Identify the following for each reaction: 2 H2 + 1 O2 --> 2 H2O CH4 + 2 O2 --> CO2 + 2 H2O 2 H2O --> 2 H2 + 1 O2 Reactants Products 2 H2 + 1 O2 2 H2O CH4 + 2 O2 CO2 + 2 H2O 2 H2O 2 H2 + 1 O2

Study guide answers 8. What is the law of conservation of mass? Mass can not be created or destroyed. 9. Why is the law of conservation of mass important to chemical equations? Because mass can not be created or destroyed, we have to balance a chemical equation. 10. What are the four clues that a chemical reaction may have taken place? 1. color change 3. solid formation 2. gas formation 4. energy change

Study guide answers 11. What is a subscript? The small number behind the element's symbol; the subscript tells how many atoms of an element in a chemical reaction. Ex: H2 = 2 atoms of Hydrogen 12. What is a coefficient? The large number in front of a molecule; the coeffient tells how many molecules you have & applies to everything in the molecule. Ex. 3 O2 is three molecules of Oxygen

Study guide answers 13. Balance Equations: 2 Ag2O → 4 Ag + 1 O2 2_ NaBr + 1 CaF2 → 2 NaF + 1 CaBr2 14. Be sure you know how to tell the number of atoms of each element in a molecule. Ex. NH3 has 1 nitrogen atom and 3 hydrogen atoms for a total of 4 atoms.

Study guide answers 15. What does it mean if a chemical symbol does not have a subscript? That there is only 1 of that atom in the formula. 16. For a chemical reaction to occur, what must happen (to the bonds)? Old chemical bonds break apart, atoms rearrange, and new bonds are formed. 17. You balance an equation by changing the coefficients, not the subscript!

Balancing Equations Race Teacher will set up partners Each person will have a balancing equations sheet (You may want a separate piece of paper to work out the inventory) After you and your partner have balanced 5 equations, bring them to me to check. Each partner must have the correct answers on their sheet to move on to the next set. The team with all the correct answers first wins The second team wins The third team wins

Exit Ticket When balancing an equation, I can only change the ____________. A. Reactant B. Product C. Coefficient D. Subscript