Seesaw

Wippe,/. balancing balancer, equalizer counterpoise rocker clipping (from coins) seesaw tilting table Elec.) tumbler switch, wir, pron, we. 

This shape (resembling a slightly bent seesaw) is the one found experimentally. 

Now we come to a very important point that will be the basis of much of the discussion in this chapter and the next. Because Kw is an equilibrium constant. the product of the concentrations ofHjO+ and OH ions is always equal to Kw. We can increase the concentration of H30+ ions by adding acid, and the concentration of OH ions will immediately respond by decreasing to preserve the value of Kk. Alternatively, we can increase the concentration of OH ions by adding base, and the concentration of H30 ions will decrease correspondingly. The autoprotolysis equilibrium links the concentrations of H30+ and OH" ions rather like a seesaw when one goes up, the other must go down (Fig. 10.10). 

Shape seesaw Hybridization dsp3 Bond angles > 90° and >120° Polar... 

Because equatorial and axial positions differ, two molecular geometries are possible for SF4. As Figure 9-22 shows, placing the lone pair in an axial position gives a trigonal pyramid, whereas placing the lone pair in an equatorial position gives a seesaw shape. 

Sulfur tetrafluoride has two possible molecular geometries. The stable isomer is the seesaw form. 

The trigonal bipyramid (PCI5) and the seesaw (SF4) are two of the four geometries for an atom with steric number 5. Example introduces the other two, T-shaped and linear. 

C09-0129. Tellurium compounds, which are toxic and have a hideous stench, must be handled with extreme care. Predict the formula of the tellurium-fluorine molecule or ion that has the following molecular geometry (a) bent (b) T-shaped (c) square pyramid (d) trigonal bipyramid (e) octahedron and (Q seesaw. 

C14-0080. Two children on opposite ends of a seesaw can be used as an analogy for a coupled reaction. Describe the coupling of spontaneous and nonspontaneous processes during the actions of a seesaw. 

The Lewis formula shows 5 electron groups around the central P atom and its electronic geometry is trigonal bipyramidal. The ionic geometry is a seesaw due to the presence of 1 lone pair of electrons on the central P atom (Section 8-11). 

SF4 seesaw shape and polar SiF4 tetrahedral shape and non-polar... 

The global opium trade of the last 30 or so years is best described as a seesaw, waxing and waning in the changing... 

Using these definitions, the pH and pOH of a neutral solution at 25 °C are both equal to 7. We can see from the expression for that [H+] and [OH ] are inversely related, and consequentially pH and pOH are inversely related. We can picture pH and pOH as sitting on opposite sides of a seesaw, as one goes up, the other always goes down. The product of the hydrogen and hydroxide concentrations will be equal to 1.0 X 10 ", while the sum of the pH and pOH will be equal to 14. In an acidic solution, the hydrogen ion concentration increases above 1.0 X 10 , the hydroxide concentration decreases, and the pH value gets smaller. The relationship between the type of solution, pH, pOH, and ion concentrations is shown in Table 13.6. The pHs of a number of common substances are presented in Table 13.7. 

The most common example of a lever is a playground seesaw. A force (a person s weight) is applied to... 

This brings us to the secret of the lever To lift an object that is heavier than the force you want to apply to the other side of the lever, you must locate the pivot point closer to the object you want to lift. If two 50-pound children sit close to the center of the seesaw, one 50-pound child close to the end of the board on the other side will be able to lift them both. 

Equation (7.52) is equivalent to the simple rule for balancing a schoolyard seesaw if the fulcrum divides the board into lengths L1 L2, then the masses mi, m2 at the two ends should satisfy m Li = m2L2 (i.e., the heavier weight should be at the shorter end) to balance the seesaw. The proof of (7.52) is presented in Sidebar 7.9. The lever rule makes it easy to determine the relative amounts of each phase present from the tie-line ratio, and thus to determine the final unknown composition variable Xg1 from (7.51). 

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