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Dimensional Analysis and Significant Figures Review 1. Solve the following problems and express the results with the correct number of significant figures and units. a. 3.894m x 2.16m = 8.41m2 b. 2.96g + 8.1g + 5.0214g = 16.1g c. 485g ÷ 9.231mL= 52.5g/mL d. 2.46cm x 2.0cm = 4.9cm2 e. 9.146s - 9.137s = 0.009s f. (5.12 x 104L) x (6.8726 x 10-9L) = 3.52 x 10-4L2 2. The mass of the sun is 1.989x1030 kg and the radius is 696000 km. What is the average density of the sun in kg/km3? In g/cm3? (Assume the sun is spherical so V= 4/3πr3.) 1.41 x 1012 kg/km3 1.41 x 104 g/cm3 3. Conversions: Express the following quantities in the units asked for: a. Speed of light, 2.998 x 108 m/s, in miles per hour and feet/min. 6.746 x 108 mph 5.880 x 1010 ft/min b. Speed of sound, 740 mph, in i. km/ hr 1200 km/hr ii. m/s 330 m/s c. Length of a C-C bond in diamond, 1.54452 Å, in cm, m, and inches. (1 m = 1010 Å) 1.54452 x 10-10 m ; 1.54452 x 10-8 cm ; 6.08079 x 10-9 in d. Temperature i. Liquid nitrogen, -195 oC, in F and K -324oF ; 78K ii. Body Temp, 98.6 oF, in oC and K 37.0oC ; 310.2K 4. What is the number of atoms present in 2.0 moles of helium gas? 1.2 x 1024 atoms 5. Convert 3.770X1027 atoms of gold to moles of gold. 6.262 x 103 moles 6. How many significant figures are in each of the following? a. 1.92 mm 3 b. 0.030100 kJ 5 c. 6.022 x10 atoms 4 h. 0.001g 5 3 e. 0.00036 cm 3 g. 1001 seconds 23 d. 460.00 L f. 100 people i. 0.01 m 4 1 1 2 7. Record the following in correct scientific notation: a. 350,000,000 cal 3.5 x 108 b. 0.0000721 mol c. 0.0000000809 Ǻ d. 765,400,000,000 atoms 7.21 x 10-5 8.09 x 10-8 7.654 x 1011 Don’t forget to study about matter and the changes it undergoes (including properties and classification), as well as accuracy, precision and percent error.