Solve the following problems either individually or in small groups. Submit pers

Question

Solve the following problems either individually or in small groups. Submit personal solutions to the TA. ASK the TA for help if you need assistance solving the problems. The German chemistFritz Haber proposed paying off the reparations imposed against Germany after World War 1 by extracting gold from seawater. Given that: (a) the amount of the reparations was $28.8 billion dollars, (b) the value of gold at the time was about $21.25 per troy ounce (12 troy ounces = 1 1b), and (c) gold occurs in seawater to the extent of 4.67 times 1017 atoms per ton of seawater (1 ton = 2000 1b), how many cubic kilometers of seawater would have to be processed to obtain the required amount of gold? Assume that the density of seawater is 1.30 g/cm3. (Habers scheme proved not to be commercially feasible, and the reparations were never fully repaid.) Data: you can find the molar mass of gold (symbol Au) on the periodic table. At 100 K, the thermal conductivity of gaseous helium is 0.730 mW/cm K (Note: the mW represents miiliWatts). What is the thermal concuctivity expressed in the units of Btu (hr ft2(degree F/ft))? Note: the thermal conductivity of a material is the heat transfer rate (Btu/hr) by conduction through a unit area (per ft2) for a unit temperature gradient (per degree F/ft). Thermal conductivities are material-specific and similar for similar materials. A protein is known to contain two atoms of copper per molecule of protein. The combustion of 100 g of the protein gave 120 mg of CuO. Estimate the molar mass of the protein. Assume that all of the copper atoms initially present in the protein molecule reacted to from CuO. The soil on an industrial site is contaminated with mercuric oxide (HgO). One gram of dry contaminated soil is heated in H2 and produces 8.1 mg of H2O. Assume no other soil component decomposes upon heating to produce H2O, what is the wt-% HgO in the contaminated soil? Numeric Answers 2.95 times 105 km3 of seewater 0.0422 Btu/(h.ft2(degree F/ft)) 1.325 times 105 g/mol 9.747 wt.-%

Explanation / Answer

120 mg CuO = 0.12 gm = 0.12/79.545 = 0.00151 moles

CuO moles = Cu moles,

Protein moles = Cu moles/2 = 0.000755 ,

Molar mass = mass/moles = 100/0.000755 = 132450 gm/mol

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