Mix vinegar and baking soda in an open or closed container, watch the weight on the scale, and figure out whether the total mass stays the same when the gas is trapped or allowed to escape.
How do I explore?
- Move the sliders to set how much vinegar and baking soda to use.
- Turn on Collect Gas to trap the gas in the syringe. Turn it off to let the gas escape.
- Click Start Reaction to pour the vinegar in.
- Turn on the Magnifier to zoom in and read the marks.
What should I do/notice?
- Watch the bubbles and the weight on the scale.
- When the gas is trapped, does the weight change?
- When the gas escapes, does the weight change?
- Where do you think the gas came from?
What about the data?
- The sim records a row at the start, every 5 seconds, and at the end.
- Each row shows the time, the weight on the scale, and how much gas was collected.
- Graph Total Mass against Time to see if the weight stays the same.
Accessibility
- Press Tab to move between the sliders, the toggles, and the Start Reaction button.
- Use the arrow keys to change a slider.
- Press Enter or Space to press a button or flip a toggle.
- Press Escape to close this window.
Mix vinegar and baking soda in an open or closed container, watch the weight on the scale, and figure out whether the total mass stays the same when the gas is trapped or allowed to escape.
Standards
5-PS1-2 Measure and graph quantities to provide evidence that regardless of the type of change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved.
Design intent
- Students mix vinegar and baking soda, then read a weighing scale and a gas syringe as the reaction runs.
- The Collect Gas toggle switches between a closed system that traps the gas and an open system that lets it escape, so students can compare the total weight of the two setups.
- Students measure and graph the mass over time, providing evidence that weight is conserved when the escaping gas is captured.
Discussion prompts
- Why does the scale reading drop when the gas is not collected but stay the same when it is?
- If matter cannot be created or destroyed, where did the missing weight go?
- How could you show that the gas has weight?
- How does changing the amount of vinegar or baking soda change the reaction?
Data format
A row is recorded automatically at the start, every 5 seconds during the reaction, and at completion. Each row holds Trial, Time (s), Solution in Flask (g), Total Mass (g), Mass of Gas Collected (g), and Gas Volume (mL). Graph Total Mass (g) against Time (s), with one line for a closed run and one for an open run.
Model details
The reaction is acetic acid plus sodium bicarbonate producing carbon dioxide. In the open system the CO2 escapes, so the scale reading drops by the mass of gas lost. In the closed system the gas is trapped in the syringe, so the total weight stays the same.
- The reaction uses 1:1 mole ratios with first-order exponential kinetics.
- Vinegar is modeled as 5% acetic acid by mass with a density of 1.01 g/mL.
- Gas volume assumes ideal-gas behavior at room temperature (24,500 mL/mol).
- Scale readings include a small random noise (well under a gram) to mimic a real balance.
- The rate depends on the amount of reactants: more material takes longer to react, and an excess of one reagent mildly speeds the reaction.