Test Review 9900 Matter and Energy

1. What do we mean by the composition of matter? 2. What is the difference between mass and weight? 3. About how many different types of atoms are there? about how many types of elements? …molecules? …compounds? 4. Zinc oxide (ZnO) is 80.3% zinc (Zn) and 19.7% oxygen (O). How many grams of each of these elements are there in a 75 g sample of ZnO? 5. List 2 differences between a compound and a mixture. 6. Give 1 example of each of the following: alloy suspension colloid solution 7. By what means can we separate mixtures? What NEVER happens while a mixture is being separated? What about the different substances in a mixture allows us to separate these substances? 8. List 5 different methods of separating mixtures. 9. The density of salt is 2.164 g/cm3. If a cube of salt has a mass of 54 g, what is the length of one side of the cube (in cm)? 10. Is density an extensive or intensive property of matter? Is density a physical or chemical property of matter? 11. When ice melts, has a chemical or physical change occurred? 12. Classify the following as exothermic or endothermic changes. freezing melting boiling cold pack burning condensation 13. What do we call the minimum amount of energy needed to start a chemical reaction? 14. What does the Law of Conservation of Energy say? 15. Convert 2.35 miles into cm. (2.54 cm = 1 inch, 5280 feet = 1 mile, 12 inches = 1 foot) 16. How many atoms of lead (Pb) are in 78.5 g of lead? 1. what the matter is made of 2. mass = the amount of matter in an object weight = the pull of gravity on the matter in an object 3. ~100 ~100 millions millions 4. X g Zn = 0.803 (75 g sample) = 60.2 g Zn X g O = 0.197 (75 g sample) = 14.8 g O 5. COMPOUND MIXTURE chem. bonds between atoms NO chem. bonds between parts fixed composition variable composition 6. bronze muddy water milk soft drinks 7. physical; chemical reactions; substances have different properties 8. magnet, filter, decant, evaporate, distill, chromatography, centrifuge 9. V =

10. intensive; physical 11. physical 12. EXOthermic ENDOthermic ENDOthermic ENDOthermic EXOthermic EXOthermic 13. activation energy 14. In any change, the total amount of energy remains constant. (Energy can be transformed, but NOT created or destroyed.) 15. X cm = 2.35 miles 5280 ft 12 inches 2.54 cm = 378,200 cm 1 mile 1 ft 1 inch 16. X atoms Pb = 78.5 g Pb 1 mol Pb 6.022 x 1023 atoms Pb 207.2 g Pb 1 mol Pb = 2.28 x 1023 atoms Pb