UnitAnalysis - 2 cross-sectional area can hold up to 3.5 x...

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1) In the early 20 th century, thin metal foils were used to study atomic structure. (a) How many in. 2 of gold foil with a thickness of 1.6 x 10 -5 in. could have been made from 2.0 troy oz? (b) If gold cost $20.00/troy oz at that time (~$1650 now), how many cm 2 of gold foil could have been made from $75.00 worth of gold. (1 troy oz = 31.1 g, d Au = 19.3 g/cm 3 )? 2) Copper is ductile. How many meters of 34-gauge wire (diameter = 6.304 x 10 -3 in) can be produced from copper in 5.01 lb of covellite, an ore of copper that is 66% copper by mass. 3) An Olympic-size swimming pool is 50.0 m x 25.0 m. (a) How many gallons of water (d = 1.0 g/mL) are needed to fill the pool to an average depth of 4.8 ft? (b) What is the mass (in kg) of water in the pool? 4) Asbestos is a fibrous silicate mineral with remarkably high tensile strength. Grunerite, a type of asbestos, has a tensile strength of 3.5 x 10 4 kg/cm 2 , meaning a bar of grunerite with a 1 cm
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Unformatted text preview: 2 cross-sectional area can hold up to 3.5 x 10 4 kg. The tensile strengths of aluminum and Steel No. 5137 are 2.5 x 10 4 lb/in 2 and 35.0 x 10 4 lb/in 2 , respectively. Calculate the cross-sectional area (in cm 2 ) of bars of aluminum and Steel No.5137 that have the same tensile strength as a bar of grunerite with a cross-sectional area of 25 mm 2 . 5) Earths oceans have an average depth of 3800 m, a total area of 3.63 x 10 8 km 2 , and and average concentration of dissolved gold of 5.8 x 10-9 g/L. (a) How many grams of gold are in the oceans? (b) How many m 3 of gold are in the oceans? (c) Given the current price of gold at $892.00/troy oz, what is the value of gold in the oceans? 6) If a raindrop weighs 65 mg on average and 5.1 x 10 5 raindrops fall on a lawn every minute, what mass (in lbs) of rain falls on the lawn in 1.5 hours? From Silberberg, Principles of General Chemistry 1 st Ed....
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