08 SEP 2006 Q. Mr. Sanford graduated from JMU. True or false? A. True. -- 11 SEP 2006 Q. All billiard balls are striped. True or false? If you ignored the cue ball, then would your answer be different? A. True. The stripes are wider on the "solid"-colored balls. -- 13-14 SEP 2006 (Per. 1,3 only) Q. What _observation(s)_ can you make that would lead you to _infer_ that we will use computers in class today? A. PC mobile lab; teacher's laptop + LCD projector Q. Which metric unit of _length_ is 10x >1 meter? A. 1 dekameter (dam) -- 15 SEP 2006 Q. A milliliter (mL) is what fraction of a liter (L)? A. 1/1000 Q. How many mL = 1 centiliter (cL)? A. 10 mL -- 19 SEP 2006 Q. What is the density of water? A. 1 g/cc Q. A cube measuring 2 cm on a side has a mass of 16 g. What is its density? A. V = 2cm x 2cm x 2cm; V = 8cc D = 16g / 8 cc = 2 g/cc -- 20 SEP 2006 (Honors) Q. 35.6 mL of H2O = ? kg A. 35.6 mL of HOH = 35.6 g of HOH, or .0356 kg Q. A _characteristic property_ is like a __?__. How are CPs useful? A. _fingerprint_. CPs may be used to infer the identity of unknown substances. [Note: A simile is a comparison using "as" or "like."] -- 21 SEP 2006 (Per. 1&3) Q. A _characteristic property_ is like a __?__. How are CPs useful? A. _fingerprint_. CPs may be used to infer the identity of unknown substances. Q. What is the _density_ of an unknown substance with a mass of 25g and a volume of 3 mL? Q. D = M/V; 3mL = 3cc; D = 25g/3cc; D = 8.3g/cc -- 22 SEP 2006 Q. 1 L = ? mL A. 1,000 mL Q. A cube 30mm on a side has a mass of 100g. What is its density? A. 30mm = 3.0cm; Volume = 27cc; D = 100g / 27cc = 3.704 g/cc -- 25 SEP 2006 Q. Three samples of the same substance have the following masses & volumes: Sample A) 5g, 2cc; Sample B) 20g, 8cc; Sample C) 30g, 12cc. What can you conclude about the density of the three samples? Support your answer with data. A. All three samples have the same density (2.5g/cc), regardless of their size and shape. Note: The ratio of mass and volume is always the same -- the mass is 2.5x bigger than the volume. -- 26 SEP 2006 Q. An object sinks in H2O. What can you infer about the density of the object relative to the density of water? A. The object is more dense than water. Q. In terms of density, explain the difference in the observed behavior of the two 12 oz. sodas. [Coke Classic & Diet Coke] A. Difference in density caused by ingredients: high fructose corn syrup vs. aspartame (NutraSweet) 12 oz. cans: 39 g of sugar; 100 mg of NutraSweet Google Search: how much sugar in a 12 oz. coke? http://www.middleschoolscience.com/dietcoke.htm http://www.nutrasweet.com/ -- 27-28 SEP 2006 [All classes (Per. 1-3)] Demo-P.O.D.s: Q. "Coke Classic" can immersed in H20 revisited. Explain why the can floats. A. The liquid in which the soda can is immersed must be more dense than water. The "aquarium" contains saltwater; D = ~1.03 g/cc. Q. "Rainbow" Column of Liquids - Assuming the graduated cylinder contains three different liquids, explain your observations in terms of density. Which layer is most dense? Least dense? A. The most dense liquid is the bottom layer in the graduated cylinder; the least dense liquid is the top layer. [Honors only] Q. A graph of mass versus density results in a straight-line graph. What does the linear relationship between mass and volume tell you about density? (I think this is a better wording of the question than '05-06.) A. For a given substance, the mathematical relationship (ratio) between mass & volume is constant, therefore, density IS a characteristic property! Q. Water spills out of a graduated cylinder when measuring the volume of an unknown sample. How will this affect both your measurement of volume and calculation of density? A. The measured volume would be lower; the calculated density would be higher. -- 20 OCT 2006 [Note: The following POD should be timed to precede the due date for the TAP foldable-poster, in order to ensure students have drawn the model correctly.] Q. Draw an "electron cloud model" of _your_ TAP element. A. (answers will vary) -- 23 OCT 2006 Q. Draw an electron cloud model for Argon (Ar). (Per. 1 & 3) -- 26 OCT 2006 Q. Draw an "electron cloud model" for Sulfur (S). (Per. 1 & 3) -- 27 OCT 2006 Q. Referring to the Periodic Table of the Elements, what is a "period?" "Group?" A. period = row; group = column Q. What is the meaning of the word "periodic?" A. recurring at regular intervals [a repeating pattern] -- 01-02 NOV 2006 IsotoPODs (Isotope PODs): Excerpt from SOL Review Booklet re: radiometric dating using carbon-14, including four (4) questions. http://www.wsanford.com/~wsanford/gr8ps/01_green/04_invisible_atom/extras/ carbon-dating/PODs_radiometric-dating.doc <-- enter URL on one line == [fill in gap] == -- 15-16 NOV 2006 Q. What is an exothermal reaction? Give an example of one. A. A chemical reaction in which thermal energy (heat) is released. -- 20 NOV 2006 Q. 250 g of CuSO4 is dissolved in one (1) liter of H2O. Is this an example of a physical change or a chemical change? A. Physical change. [Note: Add small amount of CuSO4 solution to a 250ml beaker; let the solution evaporate. Observe crystal formation.] -- 04 DEC 2006 Q. Are the following chemical equations balanced or unbalanced? If not, then try to balance the equation(s). (endothermic) ^ H3C6H5O7(aq) + 3NaHCO3(s) --> 3H2O(l) + Na3C6H5O7(aq) + 3CO2(g)| citric acid + sodium bicarbonate (baking soda) --> water + sodium citrate (salt solution) + carbon dioxide gas A. Yes, equation IS balanced. H 11 C 09 O 16 Na 03 (exothermic) Mg(s) + HCl(aq) --> MgCl2(aq) + H2(g) magnesium (solid metal) + hydrochloric acid --> magnesium chloride (salt solution) + hydrogen gas [Note: MgCl2 is commonly used as a deicer. Recover product (solution); allow water to evaporate. Test MgCl2(s) salt on water ice to see if it will melt ice.] A. No, equation IS NOT balanced. R | P Mg 1 | Mg 1 H 1 | H 2 Cl 1 | Cl 2 ^ Mg(s) + 2HCl(aq) --> MgCl2(aq) + H2(g)| R | P Mg 1 | Mg 1 H 2 | H 2 Cl 2 | Cl 2 ***Teacher's Note: Revisit the endothermic reaction [citric ACID + sodium bicarbonate (BASE) --> water + sodium citrate (salt solution), which is also a neutralization reaction (acid + base --> water + salt). Segue to "Colorful Chemical Clues" lab activity.*** mnemonic: solution = solute-ION -- 06-07 DEC 2006 Reacto-POD Q. Mr. Sanford buys a "hot pack" for his aching back. The pack is the kind you put in a microwave oven. What causes the pack to get to get hot -- a chemical- or physical change? A. Physical change -- 08 DEC 2006 Q. The pH scale, numbered from 0-14, is logarithmic. A pH of 2 is how many times stronger than 5? A. 10 x 10 x 10 = 1,000x stronger Q. What is the name of the following substance? H-I-J-K-L-M-N-O Hint: It is one of the products of a neutralization reaction. A. H-to-O -- 02 JAN 2007 Q. What is "hydrogen hydroxide?" A. Water! -- 16 JAN 2007 Q. All forms of energy can be classified as either potential- or kinetic energy; classify the six (6) forms of energy listed in PB-10-LR accordingly. A. Potential: mechanical; chemical; nuclear Kinetic: mechanical; electric; radiant; thermal -- 24 JAN 2007 Q. Draw (hah!) and label the essential parts of a lemon wet cell. A. container (lemon peel); electrolyte (lemon juice, citric acid); electrode pair (e.g., Mg/C); conducting pathway (copper wires). -- 29 JAN 2007 Q. [Use words & arrows to] Make an "energy chain" that shows the energy transformations that occurred when the lemon wet cell was connected to the following low-power electronic devices: LED; buzzer. A1. LED: chemical (potential) --> electrical --> radiant A2. buzzer: chemical (potential) --> electrical --> mechanical (kinetic) "Note: Sound is mechanical energy because of the vibrating (moving) molecules creating the sound." PB1LR -- 12 FEB 2007 Q. Why is there no such thing as a one-bulb parallel circuit? A. Because the only way to wire a one-bulb circuit is in series. -- 20 FEB 2007 Q. A string of 20 Christmas tree lights is plugged in to a 120 V 15 A AC electrical outlet. If the lights are wired in series, then what is the voltage and amperage (current) for each individual light bulb? A. Voltage = 120V/20 = 6V; Amperage = 15A AC -- 28 FEB 2007 Q. Otis Elevators (manufactured by United Technologies) regenerates electricity for the buildings they serve. Explain how the system could work. Use the words "motor" and "generator" in your answer. A. Answers will vary; should feature the words "motor" and "generator" -- 05 MAR 2006 Q. In the movie, "Star Wars," we hear sound effects when the "Death Star" explodes (near the end of the movie). Why is this unrealistic? A. "There is no sound in space because there are no molecules there to transmit the [longitudinal] sound waves." http://www.srh.noaa.gov/srh/jetstream/remote/remote_intro.htm -- 14 MAR 2006 (3.14, a.k.a., Pi Day) Q. What is Pi? Yeah, I know, it's 3.14, but what is Pi? A. The ratio between diameter and circumference: C is always a little more than 3x >D; D is always ~1/3 of C. Simmple, really! Q. A duck walked (waddled?) into a bakery and ordered a slice of pie. The sales associate asked, "Will that be cash or charge?" How did the duck reply? A. The duck replied, "Just put it on my bill." -- 09 APR 2007 Q. There is no such thing as "cold" -- it simply does not exist! Explain why the preceding statement is true. A. There is only thermal energy, more or less thermal energy. In everyday language, we call more thermal energy "hot"; less thermal energy "cold." -- 23 APR 2007 Q. [Show graph, "Tracking the Heat - Contact"] What happened at this point (~11 min)? A. The hot & "cold" water reached thermal equilibrium. -- 26 APR 2007 Q. Based upon what you know about density, explain how the Lava Lite(tm) works. A. Two liquids, similar densities, one of which appears to be a waxy substance (black goo). -- 30 MAY 2007 True or False: Heat rises. A. False. Less dense fluids rise, transferring thermal energy in the process. -- 01 MAY 2007 (Predicto-POD) Q. Predict what the "absorption of Radiant Energy" graph would look like if the 200-watt (200 W) lamp were left on for two (2) hours rather than 10 minutes. A. Eventually, the black & white "flower pots" come into "radiative balance" with the heat source: radiation absorbed equals radiation emitted. -- 04 MAY 2007 Q. A beaker of boiling water is allowed to cool until it reaches room temperature. Draw a graph that shows temperature versus time; label key temperatures. A. The graphs shows two plateaus separated by a steep negative slope: The first plateau represents the phase change from liquid to gas; the second plateau shows the water reached thermal equilibrium with the air temperature. -- 10 MAY 2007 Q. How can you tell whether an object has moved? A. By comparing the object to a frame of reference. Q. What is ultrasound? A. Beyond sound, meaning beyond the normal range of human hearing (20 - 20,000 Hz). -- 14 MAY 2007 Q. What is shown by a graph of distance versus time? A. Speed -- 16 MAY 2007 [Show "Speed Bump" comic re: average speed: extras/average-speed_comic; play song, http://en.wikipedia.org/wiki/I_Fought_the_Law] Q. How fast was Bob driving BEFORE "the law" stopped him? A. Exact speed cannot be determined, but we can assume it was 20 mph OVER the speed limit. -- 22 MAY 2007 Q. What is shown by a graph of velocity (speed) versus time? A. Acceleration -- 24 MAY 2007 Q1. How can we express Newton's 2nd Law of Motion as an equation? A1. F = ma Q2. Solve for acceleration (a). A2. a = F/m <-- Note: At a constant force (F), acceleration (a) is inversely proportional to mass (m). -- 25 MAY 2007 Show B.C. comic re: "feet belts.".] Q. Which one of Newton's Three Laws of Motion is illustrated by the comic (shown left)? A. Inertia (Newton's 1st Law of Motion) -- 29 MAY 2007 Q. What is indicated by the plateaus on the graphs (shown left)? [show graphs of speed (distance vs. time) and acceleration (velocity vs. time)] | / | ___/ | / |/ --------- A. speed graph = object is not moving (stopped); acceleration graph = object is moving at a constant velocity (not accelerating). Follow-up question: Q. How would an object that is not moving appear on a graph of acceleration? A. A plateau at the zero (0) mark on the y-axis. -- 01 JUN 2007 Q. Change only ONE word in the comic dialog "balloons" in order to make the punchline completely consistent with the definition of "work." A. Since W = F x d, "...Dad gets BUSY." should be changed to "...Dad gets MOVING." Mom is the force! -- 04 JUN 2007 Q. You may have noticed the door to the classroom has two handles: one located near the outer edge of the door; and one located near the inner edge of the door (closer to the hinges). Which one of the two door handles will require less effort force (F-sub-e) be exerted in order to close the door? Explain your answer. A. The handle near the outer edge; the force-distance trade-off explains... -- 05 JUN 2007 - Work & Power PODs [Work-P.O.D. re: amount of work equivalent to one (1) joule (1 J).] Now... Q. How much work is done to lift a 500-gram mass 20 cm? Express your answer in joules (J). A. 500g = 0.5kg; 0.5kg x 9.8 = 4.9N W = F x d W = 5N x .2m or 1 N-m or 1 J [Power-P.O.D. re: amount of power equivalent to one (1) watt (1 W).] ...and later. Q. How much power is used to lift a 500-gram mass one (1) meter in five (5) seconds? Express your answer in watts (W). A. Power (watts) = Work (joules) / time (sec) P = (5N x 1m) / 5 sec P = 1 J/sec or 1 watt [end school year]