AP Chem help please?

Question

1. A 200.0 mg piece of gold can be hammered into a sheet that is 2.4ft by 10 ft. What is the thickness of the sheet in m, using the SI prefix? Explain.

2.At 1.00atm and 25.0 degrees celcius, air has a density of 1.19g/L. What is the mass, in kg, of air in a classroom that measures 26 ft by 41 ft by 8.0 ft? Show work.

3. A copper refinery produces a copper ingot weighing 150 lb. If the copper is drawn into wire whose diameter is 1.25mm, how many meters of copper can be obtained from the ingot? Show work.

Answer 1

This is not chemistry. It is fiddly conversion between units made as difficult and boring as possible. Hate, Hate! (I have researched and taught chemistry all my working life; it is the FASCINATING study of how things react, and how properties depend on structure)

1) Divide 0.200g by density of gold to find volume (mL or cc) of gold.

Area (2.4 ft x 12 in/ft x 2.54 cm/in x 10 ft x 12 in/ft x 2.54 cm/in) x thickness of sheet (cm) = the volume you just found. Convert the thickness to mm or mum, whichever fits best.

2) 15500 mi^2 x (1609.344 m/mile)^2 = area (m^2)

3) Again, turn feet into cm. Multiply L x B x H to get volume in cm^3. Divide by 1,000 to get volume in L. Then multiply by 1.19 g/L

4) Use 1 lb = 453.592 g to convert lb to g. Divide by density of copper (g/cm^3) to get volume (cm^3) of copper. Cross-section of wire = pi x (0.125 cm x 1/2)^2. (Why the 1/2?) Divide volume by cross-section to get length.

Good luck!