I have absolutely no idea how to do it and my teacher teach hecking fast too...
Zinc reacts with hydrochloric acid and hydrogen gas.If 130g of zinc reacted completely, calculate the volume of gas formed.
Add in first line:Zinc reacts with hydrochloric acid to form zinc chloride and hydrogen gas...
What temperature of the gas? What pressure of the gas. I assume you want STP or 273 kelvin (0 degrees C) and 1 atm pressure (760 mm Hg).
Step 1. Write and balance the equation.
Zn + 2HCl ==> H2 + ZnCl2
Step 2. Convert grams Zn to moles.
moles Zn = grams/atomic mass = 130/65.4 = approx 2 but this is just a close estimate. You should repeat all of my estimates including all of the calculations that follow.
Step 3. Using the coefficients in the balanced equation,, convert mols of what you have (mols Zn) to mols of what you want (H2).
2 mols Zn x (1 mol H2 gas/1 mols Zn) = approx 2 mols H2.
Step 4. Convert mols of H2 to the desired unit. In this case you want volume H2 gas. You know 1 mol of a gas occupies 22.4 L at STP so
approx 2 mols H2 x 22.4 L/mol = ? L H2.
This procedure will work all of your stoichiometry problems.