Mississippi Science CHE.7.7
The Standard
- CHE.7
- Students will demonstrate an understanding of the structure and behavior of gases.
Plan and conduct controlled scientific investigations to produce mathematical evidence that confirms that reactions involving gases conform to the law of conservation of mass.
2026 Mississippi College- and Career-Readiness Standards for Science · Gas Laws
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students plan a vinegar and baking soda reaction that traps the gas in a sealed bag. They keep ingredient amounts the same across trials. They weigh the whole bag before and after mixing, then calculate the mass change.
What Mastery Looks Like
- Students record starting and ending masses for repeated trials and calculate each difference. They explain why the bag can inflate without gaining mass and why an open setup may lose mass.
Common Misconceptions
- Students may weigh only the liquid left behind and conclude that mass was destroyed. They may think an inflated bag has gained mass because it looks bigger. They may also treat a small scale difference as proof that mass changed.
How to Assess It
- Exit ticket: A sealed bag weighs 84.6 g before mixing and 84.5 g afterward. Calculate the difference, say whether the result supports mass conservation, and name one possible source of the difference.
Lesson moves
Ways to Teach It
Put 1 g baking soda and 15 mL vinegar in separate cups inside a gallon zip bag; seal, weigh, tip the cups, and reweigh.
Show mass readings from an open-cup reaction and ask students to explain where the missing mass went.
Hand pairs trial cards with before and after masses; have them calculate each change and match the cards to sealed or open setups.
Set a capped seltzer bottle beside an uncapped one and ask which can lose mass as bubbles escape, and why.
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Related Standards
- CHE.4.8
Plan and conduct controlled scientific investigations to produce mathematical evidence of the empirical composition of a compound.
- CHE.6.7
Plan and conduct a controlled scientific investigation to produce mathematical evidence to predict and confirm the limiting reagent and percent yield in the rea...
- CHE.6.5
Plan and conduct a controlled scientific investigation to produce mathematical evidence that mass is conserved. Use percent error to analyze the accuracy of res...
- PHS.4.2
Design and conduct investigations to produce evidence that mass is conserved in chemical reactions (e.g., vinegar and baking soda in a Ziploc© bag).
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