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Intro. to Chemistry (Paper II)
Part 1 Chemical Compounds
1. What is a compound? Explain
2. What is a chemical formula, and what does it show? Give examples.
3. What is a subscript? Give examples
4. What is a molecule? Give examples
Part 2: Chemical and Physical Properties
1. What are physical properties? Give examples
2. What are Chemical properties? Give examples
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ACTIVITY: You are provided with samples of the elements Zinc and Sulfur. Perform the tests below, describe the results, and say whether you are giving a physical or chemical property. Talk to your teacher if you are not sure.
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1..Describe the appearance of the Zinc and Sulfur.
Zinc
Sulfur
2. Are these Physical or Chemical Properties?
3. Test to see if the zinc and sulfur conduct electricity.
Result. Zinc Sulfur.
4. Do these tests show Physical or Chemical Properties?
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5. React the zinc and sulfur separately with a little dilute Hydrochloric acid (HCl) in a test tube.
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Results
Zinc
Sulfur.
6. Do these tests show Physical or Chemical Properties?
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7. Heat tiny bit of each element, Zinc and Sulfur, separately on the end of a microspatula, in the fume hood.
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Result-Zinc.
Result Sulfur.
1. D
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Place a little zinc and sulfur together in a small dry test tube, note their appearance, and then heat them strongly In the fume hood
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escribe the initial appearance of the mixture.
2. Result of heating.
3. What evidence is there that a chemical change occurred?
4. You have made a chemical compound. You cannot get the elements back by physical means. Can you name the compound?
Part 3. Summary of terminology.
Here you will get to practice some simple chemical formulas. Use the terms molecule, compound, mixture, atoms, pure substance, etc. to fill the blanks.
Sodium is an that reacts with the ________ water to form Hydrogen, whose __________
have the formula _____, and the ___________ sodium hydroxide whose formula is NaOH. The sodium
hydroxide produced dissolves in water to form a solution which is a ____________ One physical property
of Hydrogen is:_______________
Word equation: (Most metallic elements are monatomic, some gaseous elements are diatomic, ask
what this means)
Sodium ______ + water ________ form ___________of sodium hydroxide and ___________of hydrogen.
Equation. (E.C. Can you balance the atoms?)
Part 4. Obtaining the formula of the compound black copper oxide.
Here the oxygen in the black copper oxide will be taken away chemically using the element hydrogen.
1. Test for conductivity of the black copper oxide
Result:
Diagram.
Results.
Mass of Copper Oxide used..........................................................................
Mass of Copper Remaining............................................................................
Mass of Oxygen atoms chemically combined in the copper oxide.................
Questions.
1. How could you show that the red product was the METAL copper? Perform the test.
2. What product other than copper do you think was made In this reaction?
3. Do you think matter was destroyed in this reaction- Give a reason.
YOU CAN NOW TRY TO WORK OUT the FORMULA OF the BLACK COPPER OXIDE. ATOMS OF COPPER WEIGH 64 UNITS AND ATOMS OF OXYGEN WEIGH 16 UNITS.
a) What is the % by mass of Copper and Oxygen in the compound? Does this tell you the ratio of atoms in the compound?
b) Can you deduce or work out the correct formula of black copper oxide?
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