Multivariable functions

When mixing $x$ gram molecules of sulfuric acid together with $y$ gram molecules of water, the released heat can be determined by the formula:

$C(x,y) = \frac{1.786xy}{1.798x+y}$

If initially there are 5 gram molecules of acid and 4 gram molecules of water and we increase them to 5.01 and 4.04, respectively, how much additional heat is generated? Write your answer as a number rounded to three decimal places.