What is the gradual change in the types of species that live in a community. This can include primary and secondary situations.

Explanation:

Primary succession involved the colonization of a new rock substrate by living things, usually for the first time while in secondary succession involved recolonization after the first ecosystem was decimated by some form of disaster.

Primary succession occurs in newly exposed rock substrate such as after a volcanic eruption. This rock will begin by being colonized by lower plants like lichen and moss. They break down the rock into shallow soil enabling higher plants with shallow roots to colonize. This further releases the nutrients in the soil and causes the soil to be deep. Eventually, trees, that form part of the climax community will be also to be supported in the new environment.

Secondary succession occurs when this climax community gets destroyed such as in a wildfire. The secondary succession does not begin from the lower plants - mosses and lichen - like in primary succession. This is because the soil in already well formed. Usually lower higher plants- like shrubs and perennial plants- recolonize the land before higher plants - like trees - succeed until another climax community is achieved.

succession

Explanation:

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answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.