Write the reaction rate expressions for the reaction below in terms of the disappearance of the reactants and the appearance of products. give the expressions for the disappearance of the reactants first, in the order written in the chemical equation. then write the expressions for the appearance of the products in the order written in the chemical equation. write the expressions in order of appearance in the equation in the form. ± 1 x × δ[α] δt where ± is either a plus or a minus sign, not both, x is an integer, and a is a chemical species. do not include the state of matter. 2h2(g) + o2(g) → 2h2o(g)