Activity A:
Get the Gizmo ready:
Water reaction
Make sure H2 + O2 becomes H2O is selected.
Click Reset (2).
Goal: Identify a limiting reactant.
1. Count: HO is the chemical formula for water. In order to produce a single molecule of
water, how many hydrogen atoms are needed? atoms Oxygen atoms? I oxygen atom
2 hydrogen
2. Predict: Set the number of O2 molecules to five and the number of H2 molecules to eight.
A. How many oxygen atoms are present? 10 atoms Hydrogen atoms? 16 atoms
7
B. How many water molecules could form from these reactants? 8
C. After the molecules react, which reactant will be left over?
8
D. Which reactant will be the limiting reactant?
Oxygen
E. Click Play and wait until Reaction complete is shown. What happened? There
are 8 water molecules
3. Test: Click Reset. Set the number of O2 molecules to 10.
A. How many hydrogen molecules (H2) will be needed for there to be no excess
20 hydrogen
reactants? molecures Use the slider to set the number of H2 molecules to this value.
B. How many water molecules will be formed? 20
C. Click Play. What happened? 20 water molecules were formured
4. Challenge yourself: Run the Gizmo with five O2 molecules and nine H2 molecules.
A. How many of each molecule do you think will be produced by this reaction?
4 used
8 used
O2: lieft
H2: 1 left
HO: 8
4 used . 0 used
B. Click Play. How many were actually produced? O2:
1
H2:
I
H2O:
8
C. How do you explain this result?
