Chemical Equations
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C HAPTER
Chapter 1. Chemical Equations
1
Chemical Equations
Worksheet Name _____________________ Class ______________________ Date ________________ Answer each of the questions below to show your achievement of the lesson objectives. Lesson Objective: Describe chemical reactions using word equations. 1. In a chemical equation, the arrow stands for a. b. c. d.
yields comes from equals is
2. Which of the following is not a word equation? a. b. c. d.
silver + sulfur → silver sulfide burning wood → carbon dioxide and water drive north → turn left at the light water forms hydrogen and oxygen
3. A reactant is a. b. c. d.
the material formed in the reaction produced in the reaction the material acted upon the process of reacting
4. True/False: Burning is a chemical reaction. 5. True/False: Tarnish is formed when silver sulfide reacts with air. 6. True/False: Some chemical equations use an equal sign to show products. 7. The generic chemical equation: ___________ → ______________ . 8. Methane + _________ → ________ + __________. Lesson Objective: Know the correct symbols to use in order to write skeleton equations for chemical reactions. 9. A skeleton equation shows a. b. c. d.
formulas of reactants formulas of products formulas of reactants and products the process of the reaction
10. One of the following is not used to describe the physical state of a material in a reaction 1
www.ck12.org a. b. c. d.
s l g w
11. Only one of the following is true: In a skeleton equation, all the formulas must a. b. c. d.
be written correctly have balanced structures use names of materials use arrows to show direction
12. True/False: A chemical equation is a presentation of a chemical reaction. 13. True/False: The abbreviation (s) stands for “solution”. 14. True/False: Skeleton equations show the relative amounts of materials to be used. 15. Comment on the following equations a. CH4 ← CO2 + H2 O b. H2 O(s) → H2(s) + O2 (l) 16. What symbols could be written above the arrow and what do they represent? Lesson Objective: Use coefficients to balance chemical equations so that the law of conservation of mass is followed. 17. A balanced equation assumes all of the following except a. b. c. d.
the law of conservation of mass is true amount of reactants does not equal amount of product matter can neither be created nor destroyed equal numbers of atoms of each kind exist on both sides of the arrow
18. One of the following is not used in balancing equations a. b. c. d.
change subscripts on formulas change coefficients double-check accuracy of formulas make sure correct products are produced in the reaction
19. If more than one reactant or product are present, they are separated with a. b. c. d.
dash comma plus bracket
20. Which of the following represents the correct way to balance the equation for the formation of methane from carbon and hydrogen? a. C + H2 → CH4 b. C + 2H2 → CH4 c. 2C + H2 → C2 H2 2
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Chapter 1. Chemical Equations
d. 2C + 4H2 → C2 H8 21. 22. 23. 24.
True/False: True/False: True/False: True/False:
Mass does not need to be conserved in a chemical reaction. A coefficient is used in front of a chemical to indicate number of atoms in balanced equation. Subscripts can be changed in order to balance an equation. If a polyatomic ion is unchanged, it can be treated as a unit.
25. What is the problem with each of the following equations? a. H2 O → H2 + O2 b. 1N2 + 3H2 → 2NH3 26. Balance the following equations: a. b. c. d. e.
KClO3 → KCl + O2 NaCl + F2 → NaF +Cl2 Pb(OH)2 + HCl → H2 O + PbCl2 AlBr3 + K2 SO4 → KBr + Al2 (SO4 )3 C3 H8 + O2 → CO2 + H2 O
27. Write balanced equations from the word equations below. a. b. c. d. e.
sodium + water → sodium hydroxide + hydrogen hydrochloric acid + calcium carbonate → calcium chloride + water + carbon dioxide iron(III) chloride + sodium hydroxide → iron(III) hydroxide + sodium chloride phosphorous + oxygen → phosphorus pentoxide silver oxide → silver + oxygen
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