# chem

1. According to estimates, 1.0L of seawater contains on the average 4.0x10^{-9} g of gold. If gold is worth $390 per troy ounce and a troy ounce weighs 31.103 g , how many cubic meters of seawater would have a million dollars worth of gold in it?

2. Gold is measured in troy ounces, one of the units of apothecaries’ weights. In this system of weights, 1 scruple is 20 grains (exactly), 1 ounce is 480 grains (exactly), 1 ounce is 31.103 g, and 12 ounces equals 1 (troy) pound. How many scruples of gold are needed to make a ring weighing 3.77g.

3. The LD50 for a substance in the dose that would be lethal for 50% of the population that receive that dose. The LD50 for aspirin in rats is 1.75 grams per kilogram of body weight. How many aspirin tablets, each of which contains 325mg of aspirin, would you have to feed to a rat weighing 290. g to give him this dose?

4. At sea level, sound travels at about 740 miles per hour.

How far will it travel in 5.75 seconds?

If a shot could be heard around the world, how long would it take the sound of a shot to go around the world at the equator? The circumference of the earth at the equator is about 4.01x10^{7}m.

5. If a person weighing 165 pounds contains 5.37 g of magnesium. How much magnesium will a person weigh 90kg contain? (1kg = 2.2 pounds)

6. Convert 65 miles per hour to meters per second. (1 mile = 5280ft; 1ft = 12in;1in =2.54cm)

7. A lead sphere has a diameter of 1.88cm. How many lead (Pb) atoms are in the sphere? The density of lead is 11.4g/mL. Volume of a sphere =(4/3)*πr^{3}

8. A student was given a bag of lead shot (small spheres of lead all the same size) and asked to find the volume of a single average pellet. The student first weighed a beaker and found it weighed 65.78g. He then counted 50 of the pellets into the beaker and found it now weighed 103.11g. The density of lead is 11.4g/mL. What is the volume of a single shot?

9. What is the mass of a single atom of gold in kilograms?

10. Concentrated sulfuric acid has a density of 1.84g/mL.

What is the volume of 50.0g of the acid?

What is the mass of 50.0mL of the acid?

11. How many atoms of gold are in a ring with a mass of 2.03g?

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