Mississippi Science CHE.6.5
The Standard
- CHE.6
- Students will demonstrate an understanding of the types, causes, and effects of chemical reactions.
Plan and conduct a controlled scientific investigation to produce mathematical evidence that mass is conserved. Use percent error to analyze the accuracy of results.
2026 Mississippi College- and Career-Readiness Standards for Science · Chemical Reactions
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students plan a reaction in a sealed container and decide what to keep the same across trials. They weigh the whole setup before and after mixing. They use percent error to compare the measurements.
What Mastery Looks Like
- A student can weigh the entire sealed setup before and after the reaction. They divide the absolute mass difference by the starting mass and multiply by 100. If the readings differ, they check for leaks, spills, or scale error.
Common Misconceptions
- Students may weigh only the liquid and leave the gas out of their total. They may think bubbles mean matter disappeared. Some divide by the final mass when calculating percent error.
How to Assess It
- Exit ticket: A sealed bag weighs 42.8 g before mixing and 42.7 g after. Calculate percent error using the starting mass, then name one thing you would check to explain the difference.
Lesson moves
Ways to Teach It
Give pairs a zip bag with 5 mL vinegar in a cup and 1 g baking soda outside it; seal, weigh, tip, reweigh.
Ask, 'If one bag is open and one is sealed, what must stay the same to make the comparison fair?'
Hand out three before-and-after mass pairs; students calculate percent error and sort them from most to least accurate.
Weigh a sealed soda bottle, open it briefly to release gas, recap it, then weigh it again and discuss the change.
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Printable CHE.6.5 Worksheet
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Related Standards
- PHS.4.4
Use mathematical and computational analysis to examine evidence that mass is conserved in chemical reactions using simple stoichiometry problems (1:1 mole ratio...
- CHE.7.7
Plan and conduct controlled scientific investigations to produce mathematical evidence that confirms that reactions involving gases conform to the law of conser...
- 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...
- 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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