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1、Chemistry Concepts sodium bicarbonate (a base) and citric acid (an acid) - for the bubbling to produce carbon dioxide18. Why does bubbling occur when you drop Alka-seltzer into water?The Citric Acid (an acid) combines with Sodium Bicarbonate (baking soda - a base) to make bubbles - carbon dioxide .
2、and fool you into thinking that something important is going on and that the bubbling will make you feel better. Actually, it is the aspirin that makes you feel better.19. How many electrons are LOST by elements in the Alkali Earth Metal family when they combine with another element in a chemical re
3、action?220. How many electrons are LOST by elements in the Alkali Metal family when they combine with another element in a chemical reaction?121. How many electrons are GAINED by elements in the Halogen family when they combine with another element in a chemical reaction?122. How many electrons are
4、LOST by elements in the Noble Gas NONE - they have a full outer shell and do not combine easily family when they combine with another element in a chemical reaction?with other elements. They are found in the pure form in nature.23. What is the role of “universal indicator“ in chemical reactions?Univ
5、ersal indicator is not a catalyst. It is not an inhibitor. It does not “interact“ with the reactants. It only reveals to the pH of the liquid.24. How can you PROVE that sugar, colored dye, or salt when added to water are NOT examples of chemical changes?You can evaporate the water and then allow it
6、to cool through condensation. The condensed water is pure H2O that does not contain any of the original sugar, colored dye, or salt. All of the sugar, salt, or dye is left behind when water evaporates.25. When alka-seltzer is dropped into ammonia & universal indicator a color change occurs. What doe
7、s this mean?The color change (a change in pH) means that the alka seltzer has reacted with the ammonia. The change in color shows a change in pH and therefore is an indication that a chemical change DID take place.26. What term is used to describe the process in which a solid changes into a liquid?m
8、elting27. What term is used to describe the processin which a solid changes directly into a gas?sublimation28. What term is used to describe the process in which a liquid changes into a solid?freezing29. What term is used to describe the process in which a liquid changes into a gas?evaporation30. Wh
9、at term is used to describe the process in which a gas changes into a liquid?condensation31. What term is used to describe the process in which a gas changes directly into a solid (as in water vapor turning into snow)?sublimation32. What charge do electrons have?Negative charge33. What charge do pro
10、tons have?Positive charge34. What charge do neutrons have?NO charge!35. Where are electrons located?Electrons swarm around the nucleus. They are not part of the central mass of the atom, but move freely in a “swarm“ in energy shells a distance away from the nucleus.36. Where are protons located?In t
11、he nucleus of the atom37. Where are neutrons located?In the nucleus of the atom38. What do we call electrons that are used in the bonding of atoms into new compounds?Valence electrons39. When looking at the periodic table, what piece of information tells us the number of electrons and protons that a
12、n element has?The atomic number40. What does energy have to do with a chemical reaction?Energy is either given off (exothermic) or absorbed (endothermic) in all chemical reactions.41. Is the appearance of bubbling a totally reliable indicator that a chemical reaction has taken place?NO!42. Is the ap
13、pearance of a color change a totally reliable indicator that a chemical reaction has taken place?NO!43. Is the appearance of a precipitate a totally reliable indicator that a chemical reaction has taken place? Give an example from our lab/demonstration series.Probably - the creation of Calcium carbo
14、nate (CaCO3) in the lime water demonstration.44. Is a change in pH a totally reliable indicator that a chemical reaction has taken place?Not really. After all, you could dilute acetic acid (vinegar) even more than its store-bought strength of 5 per cent and you would get a weaker solution that would
15、 yield a change in pH. However, this would NOT mean that a chemical reaction had taken place.45. What is the only totally reliable clue that a chemical reaction has taken place?The creation of a new substance with different properties than the reactants.46. What type of chemical reaction starts with
16、 two or more reactants and ends up with one totally new product?Synthesis47. What type of chemical reaction starts with one complex compound and ends up with two or more simpler compounds?Decomposition48. What type of chemical reaction starts with two or more reactants and ends up with two or more quite different products? When you look at the atoms involved it appears that the compounds on the products side have changed “partners“ fr
