How can you figure out how many atoms thick the coating of zinc is on a steel washer?????

Question

you are given 2 galvinized steel washers, 3m HCl, and appropriate meausuring devices. so what do you do????

Answer 1

You will find it difficult but possible to find a measuring tool that reads in very small dimension. It is easier to get an analytical balance to weigh the specimen and your results would be more precise.
1. Weigh the zinc coated washer.
2. Strip the zinc coating using the hydrochloric acid solution. Do not overdo this process or the acid will remove some of the steel. An inhibited acid solution is the preferred media.
3. Wash with water and dry the stripped washer.
4. Weigh the washer.
5. With a micrometer, measure the thickness of the washer.
6. Calculate the area of the washer. A=W/(densityx thickness). Density of steel is 7.85 gm/cc.
7. The area of the steel is also the area of the zinc coating.
8. Calculate the thickness of the coating. T=W/(density x Area). The density of zinc is 7.14 gm/cc.
9. Divide thickness by the atomic diameter of zinc.

Answer 2

First you measure the thickness of the steel with the zinc coating, then remove the zinc with the HCl and measure the bare steel. Then you know the thickness of the zinc. After that is is easy, dividing the coating thickness by the stacking density of zinc, to figure out how many atoms thick the coating was.

Answer 3

1. let HCl react with one of the steel washers
2. Measure the thickness in cm, of the Zn layer (comparing the thickness of the steel washer before and after inmersing it into HCl.
3. Density of Zn is 7.14 g/cm3. Molar density would be 0.1098 moles of Zn/cm3 and atom density would be 0.1098 * 6.023*10^23 atoms/cm3. That would theoretically mean that if we were to obtain 1 cm line by adding Zn atoms one to another, we would need (0.1098*6.023*10^3)^3 Zn atoms (cubic root) = 40439434 atoms.
4. Now all that is left to do is calculate how many atoms thick the coating is. We do that by multiplying 40439434 with the thickness we measured at step 2.