PhET Activity for MS-PS1-5: Balancing Chemical equations

DIRECTIONS:
1. You are on the initial screen. Click on the 'Intro' button to begin.
2. You will see the 'Make Ammonia' reaction: N₂ + H₂ → NH₃.
3. Notice the coefficient steppers (up/down arrows) below each chemical formula. Click the arrows for N₂ and observe how the number of molecules changes in the box above.
4. At the bottom, notice the three reaction options: 'Make Ammonia', 'Separate Water', and 'Combust Methane'.
5. At the top, find the 'Tools' dropdown menu currently set to 'None'.
Spend 2-3 minutes exploring the 'Intro' screen. Try changing the coefficients for all reactants and products. Switch between the three different reactions to see how the molecules change. Do not try to balance anything yet, just get familiar with the controls.

QUESTION: Are you acquainted with the tools in this simulation?

DIRECTIONS:
1. Ensure you are on the 'Intro' tab with the 'Make Ammonia' reaction selected.
2. Click the 'Tools' dropdown menu at the top and select 'Balance Scales'.
3. Do not change any coefficients yet. They should all be 0.

QUESTION: With all coefficients at 0, what do the balance scales show?

DIRECTIONS:
1. Starting with the 'Make Ammonia' reaction and the 'Balance Scales' tool, set the coefficient for N₂ to 1.
2. Set the coefficient for H₂ to 1.
3. Set the coefficient for NH₃ to 1.

QUESTION: With one molecule of each substance, the reactant side has ___ Nitrogen atoms and ___ Hydrogen atoms, while the product side has ___ Nitrogen atom and ___ Hydrogen atoms.

(a)  

DIRECTIONS:
1. Continue with the 'Make Ammonia' reaction and 'Balance Scales' tool.
2. Click the orange 'Reset' button to set all coefficients to 0.
3. Your goal is to make the scales for both Nitrogen and Hydrogen level.

QUESTION: Describe the steps you took to balance the equation. Which element did you balance first, and what challenges did you encounter?

DIRECTIONS:
1. Ensure the 'Make Ammonia' reaction is balanced. You should see a smiley face appear.
2. If you are stuck, the correct coefficients are 1 for N₂, 3 for H₂, and 2 for NH₃.

QUESTION: The balanced chemical equation for making ammonia is ___ N₂ + ___ H₂ → ___ NH₃.

(a)  

DIRECTIONS:
1. At the bottom of the screen, select the 'Separate Water' reaction.
2. The equation H₂O → H₂ + O₂ will appear. The scales for Hydrogen and Oxygen will also appear.

QUESTION: In the reaction to separate water, the reactant is (a)   .

DIRECTIONS:
1. With the 'Separate Water' reaction selected, use the steppers to balance the equation.
2. Tip: You will need 2 H₂O molecules to start.

QUESTION: In the balanced equation 2 H₂O → 2 H₂ + O₂, what does the '2' in front of H₂O mean?

DIRECTIONS:
1. Keep the 'Separate Water' reaction balanced (2 H₂O → 2 H₂ + 1 O₂).
2. Click the 'Tools' dropdown menu at the top and select 'Bar Charts'.

QUESTION: How do the bar charts show that the equation is balanced?

DIRECTIONS:
1. At the bottom of the screen, select the 'Combust Methane' reaction.
2. The equation is CH₄ + O₂ → CO₂ + H₂O.
3. The tool should still be set to 'Bar Charts'.

QUESTION: The elements involved in the combustion of methane are ___, ___, and ___.

(a)  

DIRECTIONS:
1. Ensure you are on the 'Combust Methane' reaction.
2. Use the steppers and the Bar Charts (or switch to Balance Scales) to balance the equation.

QUESTION: Arrange the steps in a logical order for balancing the equation CH₄ + O₂ → CO₂ + H₂O.