MS-PS1-2: Spotting a Chemical Reaction from Property Data
Also called NGSS MS-PS1-2 · Topic: Chemical Reactions · Physical Science
The Official Wording
Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
Clarification statement: Examples of reactions could include burning sugar or steel wool, fat reacting with sodium hydroxide, and mixing zinc with hydrogen chloride.
Assessment boundary: Assessment is limited to analysis of the following properties: density, melting point, boiling point, solubility, flammability, and odor.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-PS1-2 Means in Plain English
Middle schoolers record properties of the starting substances and of what is left afterward, then use that data to decide whether a chemical reaction took place. If the products have new properties, like a different melting point or smell, a new substance formed.
The evidence comes from six properties only: odor, density, solubility, flammability, and melting and boiling points. It builds on 5-PS1-4, where mixing can form a new substance, and leads to MS-PS1-5, which uses atom models to show why mass stays the same.
MS-PS1-2 I Can Statements
- I can record properties of substances before and after they interact.
- I can use property data to decide if a new substance formed.
- I can tell a chemical change from a change of state.
MS-PS1-2 Worked Example
A teacher demonstration that heats two solids side by side: table sugar and candle wax.
When sugar and candle wax are heated, which one turns into a new substance?
Set It Up: Table sugar and candle wax in separate foil cups, a hot plate run by the teacher, cups of water for a solubility test and a data table.
- Before heating, drop a pinch of each into water and note the odor.Sugar dissolves, wax floats, both nearly odorless
- Heat both foil cups until the wax is liquid and the sugar turns dark.Wax clear, sugar bubbling brown then black
- Let both cool, then test each solid in water again.Wax still floats, the black solid will not dissolve
- Compare odors and try to melt each solid a second time.Wax melts again, the black solid does not, burnt smell
The wax kept its properties after melting and cooling, but the sugar became a black solid that neither dissolves nor melts, so only the sugar reacted.
Why it works: Strong heat breaks sugar down into new substances, including carbon and water vapor, while melting wax only changes its state.
Common Mistakes with MS-PS1-2
Calling every change a reaction
“The wax melted, so it reacted.”
Try this: Melting changes only the state. Test the cooled wax again: if its properties match the start, no new substance formed.
Using color alone as proof
“It turned brown, so it is a new substance.”
Try this: A color change is a clue, not proof. Check a measured property, like solubility or melting point, before and after.
Testing only the after sample
A data table with no starting row
Try this: Record every property for the starting substances first, because a reaction is only clear when you compare before and after.
Where MS-PS1-2 Fits
Practice MS-PS1-2
Quick Check
- Ice melts into water. Is that a chemical reaction?
- Burned steel wool leaves a crumbly dark solid that will not burn again. What does that show?
- Why test properties before mixing as well as after?