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Chem2

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Chem2

1. 1. Ratios and dimensional analysis<br />
2. 2. Do now<br />1. A classroom is 7.0 m wide, 10 m long, and holds 25 people. What is the population density of the classroom?<br />2. Scientifically notate: 84.029 ; 0.000541 ; and 623.000<br />
3. 3. Ratios<br />speed = distance/time<br />density = mass/volume. <br />d = m/v<br />(mnemonic: DMV)<br />
4. 4. Ratios<br />e.g. If a metal block has a mass of 75 grams and a volume of 22 cubic centimeters, what is its density?<br />75 g/22 cm3= 3.4 g/cm3<br />
5. 5. Density of some common substances<br />
6. 6. Ratios<br />
7. 7. Ratios<br />The density of air is .0013 g/cm3. <br />Find the mass of 200 cm3 of air.<br />d=m/v<br />m/v = d<br />m=dv<br />m= .0013 g/cm3 x 200 cm3<br />
8. 8. Ratios<br />Tonya goes swimming. When she takes a deep breath and holds it, she is able to float on water. When she exhales, she sinks. Why?<br />
9. 9. Q: How do you not sink in quicksand?<br />(video)<br />
10. 10. Dimensional analysis<br />One of the most useful things! Ever!<br />Q. How many seconds are there in 1 hour?<br />1 hr x 60 min/1hr x 60 sec/1min = ?<br />
11. 11. Dimensional analysis<br />1 in = 3.54 cm<br />1 ft = 12 in<br />Q. How many feet are in 86 cm?<br />
12. 12. Practice<br />1 m = 100 cm; 1 cm = 10 mm<br />1 in = 2.54 cm<br />1. Convert 75 mm to inches.<br />75 mm x 1 cm/10 mm x 1 in/2.54 cm = <br />
13. 13. Quiz<br />