84.9 g of solid iron reacts with oxygen gas forming iron(III) oxide. How many moles of oxygen will react

1.14 moles of oxygen will react

Explanation:

The balanced equation of reaction between iron and oxygen is  

4 Fe + 3 O₂  → 2 Fe₂O₃

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of each compound participate in the reaction:

The molar mass of iron being Fe 55.85 g/mole, then the following amount of mass reacts by stoichiometry: 4 moles* 55.85 g/mole=223.4 g

You can apply the following rule of three: if by stoichiometry 223.4 grams of Fe react with 3 moles of O₂, 84.9 grams of Fe react with how many moles of O₂?

moles of O₂= 1.14 moles

1.14 moles of oxygen will react

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