Take a look at a simple reaction like the one below:
In this reaction some reactant A is turned into some product B. The rate of reaction can be represented by a decrease in concentration of A over time or as the increase of B over time. This is written:
Answer:
0.139 rad
Explanation:
We use Snell's law 
, where if 
is the <em>refractive index</em> of the medium containing the <em>incident ray</em>, 
would be the <em>incident angle</em>, and if 
is the <em>refractive index</em> of the medium containing the <em>refracted ray</em>, 
would be the <em>refraction angle</em>, which we want, so we do:
And finally:
We then insert our values:
