How many moles of water are produced if 5.43 mol PbO2 are consumed?

10.86 moles of water are produced

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

Reaction

Pb + PbO₂ + 2H₂SO₄ ⇒ 2PbSO₄ + 2H₂O ( a car battery reaction)

From the equation :

mol ratio PbO₂ : H₂O = 1 : 2⇒ 1 mol PbO₂ produces 2 mol H₂O

so for 5.43 mol PbO₂ consumed,  mol H₂O :

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

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