Answer:
[tex]r_{H_2}=-2r_{CH_3OH}[/tex]
Explanation:
Hello!
In this case, for the reaction:
[tex]CO(g)+ 2 H_2(g) \rightarrow CH_3OH(g)[/tex]
In such a way, via the rate proportions, that is written considering the stoichiometric coefficients, we obtain:
[tex]\frac{1}{-1} r_{CO}=\frac{1}{-2} r_{H_2}=\frac{1}{1} r_{CH_3OH}[/tex]
Whereas the reactants, CO and H2 have negative stoichiometric coefficients; therefore the rate of disappearance of hydrogen gas is related to the rate of appearance of methanol as shown below:
[tex]\frac{1}{-2} r_{H_2}=\frac{1}{1} r_{CH_3OH}\\\\r_{H_2}=\frac{-2}{1} r_{CH_3OH}\\\\r_{H_2}=-2r_{CH_3OH}[/tex]
Which means that the rate of disappearance of hydrogen gas is negative and the rate of appearance of methanol is positive.
Regards!