A gas is confined to a cylinder under constant atmospheric pressure, as illustrated in the following figure. When the gas undergoes a particular chemical reaction, it absorbs 829 J of heat from its surroundings and has 0.69 kJ of P−V work done on it by its surroundings.

What is the value of ΔH for this process?

What is the value of ΔE for this process?

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

points

explanation:

yes the answer is total mass in unchanged   : )