Which of the following reactions represents an exothermic reaction? nh3(g) + 12.0 kcal ½n2(g) + 3/2 h2(g) ch4 + 2o2 co2 + 2h2o + 212,800 cal c + 2s cs2, h = 27,550 cal c(graphite) c(diamond), h = 0.45 kcal 2h2o 2h2 + o2, h = +58 kcal

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2

explanation:

0.07 g/cm³

1.37 g/cm³