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Chemistry II Test Review

Chemistry II Test Review. 1). What are the five “evidences of a chemical reaction? Give an example of each. color change : fire burns wood to black ashes temperature change : a chemical ice pack cools down when “cracked.” gas released : smoke from a fire

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Chemistry II Test Review

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  1. Chemistry II Test Review

  2. 1) What are the five “evidences of a chemical reaction? Give an example of each. color change: fire burns wood to black ashes temperature change: a chemical ice pack cools down when “cracked.” gas released: smoke from a fire precipitate: two clear liquids are combined to and a white solid appears new properties: poisonous chlorine gas when mixed with sodium, becomes edible salt.

  3. 2) What is a precipitate? a precipitate is a solid formed when two liquids are reacted together.

  4. 3) What is the Law of Conservation of Mass? Explain what it means in a chemical reaction. Law of Conservation of Mass: Matter is neither created or destroyed in a chemical reaction, it means the total mass of the products will be the same as the total mass of the reactants.

  5. Use the following compounds to answer #4-6 a) FePO4 b) NH4NO3 c) Mn(NO3) 3 d) 3H2O 4) How many molecules are of each one is shown? A) 1 B) 1 C) 1 D) 3

  6. Use the following compounds to answer #4-6 a) FePO4 b) NH4NO3 c) Mn(NO3) 3 d) 3H2O 5) How many elements in each one is shown? A) 3 B) 3 C) 3 D) 2

  7. Use the following compounds to answer #4-6 a) FePO4 b) NH4NO3 c) Mn(NO3) 3 d) 3H2O 6) How many atoms in each one is shown? A) 6 B) 9 C) 13 D) 9

  8. 7) Which of the equations below are balanced? H2 (gas) + O2(gas)  H20 (liquid) 2H2 (gas) + O2(gas)  H20 (liquid) 2H2 (gas) + O2(gas) 2H20 (liquid) 2H2 (gas) + 2O2(gas)  H20 (liquid)

  9. 8)Write the balanced equation for number 7 in words. 2H2 (gas) + O2(gas) 2H20 (liquid) two hydrogen molecules plus one oxygen molecule yields (or produces) two water molecules

  10. Copy the balanced equation from #7 and label the products, coefficients, and reactants. 9) coefficients 2H2 (gas) + O2(gas) 2H20 (liquid) products reactants

  11. 2H2 (gas) + O2(gas) 2H20 (liquid)Extra discussion:A) How many molecules of each one is shown.2 H2molecules and 2 H2O moleculesB) How many elements in each one is shownreactant = two elements -Hydrogen and oxygenproduct = two elements -Hydrogen and oxygen C) How many atoms in each one is shown?reactant = 4 Hydrogen and 2 oxygenproduct = 4 Hydrogen and 2 oxygen Copy the balanced equation from #7 and label the products, coefficients, and reactants. 9)

  12. Draw a dot diagram of Sodium. Use the dot diagramto explain why it loses electrons. 10) Na Sodium is a metal and likes to lose an electron. It is easier to lose one electron to become more stable than gain 7 electrons.

  13. Draw a dot diagram of chlorine. Use the dot diagram to explain why it gains electrons. 11) Cl Chlorine is a nonmetal and likes to gain an electron. It is easier to gain one electron to become more stable than lose 7 electrons.

  14. Based on #10 & 11, what type of elements gain electrons? Which ones lose electrons? 12) • Metals (on the left) have fewer electrons in their outer ring, so they are electron losers (donors). • Non-Metals (on the right) have nearly full outer rings, so they tend to grab or gain electrons.

  15. 12) continued electron gainers electron losers

  16. Give the number of protons, neutrons and electrons for the element boron. (hint: APE MAN). 13) • A tomic # - 5 Boron • P rotons - 5 • E lectrons - 5 • Mass - 11 • A tomic # - 5 • N eutrons - 6 P 5 N 6

  17. Draw a Bohr Model of Boron. Be sure to show the protons, neutrons and electrons. 14) P 5 N 6 A tomic # - 5 Boron P rotons - 5 E lectrons - 5 Mass - 11 A tomic # - 5 N eutrons - 6

  18. Sketch a periodic table. Draw an arrow to show how you would find elements with similar properties. 15) Elements with similar properties are found in the same group or family They are the columns on the periodic table Groups / families

  19. What is “APE MAN” and what does it mean? 16) • A • P • E • M • A • N tomic number rotons lectrons ass number tomic number eutrons All equal A subtraction problem

  20. Compare a chemical change to a physical change (be sure and define them) and give an example of each. 17) • Chemical Change: a change that produces a new substance (it can not be changed back without a chemical reaction. Example: burning a stick. • Physical Change: a change that changes the physical properties of the substance, but doesn’t change what it is. Example: tearing paper

  21. What is a subscript 18) • Subscript: A subscript is the “small number” that shows how many of a particular element is in a compound. 3H20 The little two in H20 tells us there are two hydrogen atoms in each water molecule

  22. What is a coefficient 19) • Coefficient: A coefficient is the “big number” that shows how many of the compound is being used. 3H20 The big three in front of the H20 tells us there are three water molecules (compounds).

  23. Describe phase changes. Is it a chemical or physical change? 20) phase change: A TYPE OF PHYSICAL CHANGE - moving from one state of matter to another: Examples melting: solid  liquid boiling: liquid  gas condensing: gas  liquid freezing: liquid  solid

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