If 7.0 moles of HCl is added to enough iron that the HCl is completely used up, how many moles of hydrogen gas will be produced?

3.5 mol

Explanation:

Step 1: Given data

Moles of HCl: 7.0 mol

Step 2: Write the balanced equation

Fe(s) + 2 HCl(aq) ⇒ FeCl₂(aq) + H₂(g)

Step 3: Calculate the moles of H₂ gas produced from 7.0 moles of HCl

According to the balanced equation, the molar ratio of HCl to H₂ is 2:1.

7.0 mol HCl × 1 mol H₂/2 mol HCl = 3.5 mol H₂

heat or electricity in the atmosphere- c.