( Equilibrium ( ( ( diagrams ( are ( obtained ( by ( theoretical calculations ) ) ) ) ) , ) ( ( Although ( they ( ( define clearly ) ( ( ( the conditions ) ( ( under which ) ( metal ( can ( be produced ) ) ) ) ) ( -LRB- ( ( the ( clear area ) ) -RRB- ) ) ) ) ) ) ( , ( ( in practice ) ( , ( ( ( the ( useful part ) ) ( of ( the ( clear area ) ) ) ) ( ( may ( be ( reduced ( by ( considerations ( of ( gas ( composition ( and ( reaction rates ) ) ) ) ) ) ) ) ) ) . ) ) ) ) ) ) ) )
(ROOT (S (ADVP (RB Equilibrium)) (PRN (S (NP (NNS diagrams)) (VP (VBP are) (VP (VBN obtained) (PP (IN by) (NP (JJ theoretical) (NNS calculations)))))) (, ,)) (SBAR (IN Although) (S (NP (PRP they)) (VP (VB define) (ADVP (RB clearly)) (NP (NP (NP (DT the) (NNS conditions)) (SBAR (WHPP (IN under) (WHNP (WDT which))) (S (NP (NN metal)) (VP (MD can) (VP (VB be) (VP (VBN produced))))))) (PRN (-LRB- -LRB-) (NP (DT the) (JJ clear) (NN area)) (-RRB- -RRB-)))))) (, ,) (PP (IN in) (NP (NN practice))) (, ,) (NP (NP (DT the) (JJ useful) (NN part)) (PP (IN of) (NP (DT the) (JJ clear) (NN area)))) (VP (MD may) (VP (VB be) (VP (VBN reduced) (PP (IN by) (NP (NP (NNS considerations)) (PP (IN of) (NP (NN gas) (NN composition) (CC and) (NN reaction) (NNS rates)))))))) (. .)))
Equilibrium diagrams are obtained by theoretical calculations, Although they define clearly the conditions under which metal can be produced (the clear area), in practice, the useful part of the clear area may be reduced by considerations of gas composition and reaction rates.
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN product)) (SBAR (WHNP (WDT that)) (S (VP (MD may) (VP (VB be) (VP (VBN produced) (PP (IN by) (NP (DT a) (NN reaction))) (PP (IN under) (NP (VBN specified) (NNS conditions))))))))))) (VP (VBZ is) (VP (VBN called) (NP (JJ theoretical) (NN yield)))) (. .)))
The amount of product that may be produced by a reaction under specified conditions is called theoretical yield.