Chemical is the chemical reactions mechanical is the physical reactions.
I think g (sorry if it’s wrong)
Below are the choices:
Check all that apply
<span>( ) A(g) + B(g) ---> C(g) </span>
<span>( ) 2A(g) +2B(g) ---> 5C(g) </span>
<span>( ) A(s) + B(s) ---> C(g) </span>
<span>( ) 2A(g) + B(g) ---> C(g)
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When a gas is evolved during a chemical reaction, the gas can be imagined as displacing the atmosphere - pushing it back against the atmospheric pressure. The work done is therefore V*P where V is the volume of gas evolved, and P is the atmospheric pressure.
<span>A(g) + B(g) ---> C(g) In this reaction 2 volumes of reagent combine to form 1 vol of product. The total volume falls, so the work done is negative (the atmosphere does work on the gaseous system). </span>
<span>2A(g) +2B(g) ---> 5C(g) 4 vols of reagent combine to form 5 vols of product. The total volume increases and positive work is done. </span>
<span>A(s) + B(s) ---> C(g) we can assume that the volume of gas produced exceeds the volume of solid consumed, so again positive work is done. </span>
<span>2A(g) + B(g) ---> C(g) In this reaction 3 volumes of reagent combine to form 1 vol of product. The total volume falls, so the work done on the atmosphere is negative</span>
The answer is B. The earth's axis is tilted so that the Northern Hemisphere faces the sun. Hope this helps and good luck! :)