I have these questions on a chemistry test and I have no clue how to solve them or what the answers could be. I'm stressing because I need this test in TODAY. Questions will be in the description.

Question

For the reaction 4H2O + 3Fe → Fe3O4 + 4H2 how many grams of iron oxide (Fe3O4) will be produced if 112 g of iron (Fe) reacts completely with water?

For the reaction Zn + 2HCl → ZnCl2 + H2 what volume of hydrogen gas (H2) at STP will be produced if 130 g of Zn reacts completely with hydrochloric acid (HCl)?

for the reaction H2 + Br2 → 2HBr how many moles of hydrogen bromide (HBr) will be formed if 5.6 dm^3 of hydrogen gas (H2) reacts completely with bromine (Br2)?

Answer 1

Zn + 2HCl → ZnCl2 + H2

from 130 g Zn what volume of hydrogen gas (H2) at STP

Use these conversion factors:

1. molar mass Zn
2. 65.38 g Zn = 1 mol Zn
3. mole ratio (coefficients in balanced equation)
4. 1 mol Zn = 1 mol H2
5. standard molar volume (gas at STP)
6. 1 mol H2(g) = 22.4 L H2

The calculation:

1. (130gZn / 1) (1molZn / 65.38gZn) (1molH2 / 1molZn) (22.4L H2 / 1molH2)
2. =130÷65.38×22.4
3. =44.54 L H₂

Hope this helps. All of these questions are basically the same.

Note that a cubic decimeter is the same thing as a liter.

1 dm³=1 L