What is the area that 1 litre of gasoline would spread above the sea? I am studying for a general chemistry test with Atkins and Jones "Principles of Chemistry" 5th edition.

In the Chapter 18, page 743, section 18.3, there is this funny question:


  How would you estimate the area that 1 litre of gasoline would spread
  above the water surface?


Observation: I translated it from the Brazilian Portuguese edition. The English version may have different units, but the idea should be the same.

Let's say that the water body is the sea. But it could be a big lagoon, too. It doesn't really matter.

It got me thinking and now I'm stuck. How can we do that?
The hint here assumes a layer thickness of (crude) oil of about 1 mm. If I remember the pictures in the News around Deepwater Horizon correctly, and compare what I saw with own eyes at the local petrol station, petrol has a lower viscosity; likely spreads out wider than crude oil.

From here we learn the layer thickness is much lesser than 1 mm (millimetre), namely 168 nm (nanometre); hence all these colourful interference patterns in visible light.

$$ 1 \text{ L} = 1 \text{ dm}^3 =  10^{24} \text{ nm}^3$$

Deviding by 168 nm provides with googles built-in calculator an area of about $$5.95 \times 10^{21} \text{ nm}^2 = 5952 \text{ m}^2$$

To set this into a context, UEFA and FIFA agreed on the size of European Football / Association (soccer) field ($ 105 \times 68 \text{ m}$) which equals $7140 \text{ m}^2$.

Addendum:  According to this, an American Football field measures "$120.0 \text{ yd } (109.73 \text{ m}) \times 53.3 \text{ yd } (48.74 \text{ m})$ or $6400 \text{ yd}^2 (5351.2 \text{ m}^2$)".