S’More Lab
chemical and physical changes in everyday activities
Purpose
When food is prepared and cooked, it often causes substances to change. For
example, butter melts to a liquid when it is heated. Water changes to steam
when it boils in a kettle. Bread dough rises and becomes a crusty loaf when it is
baked. In some of these changes, new substances are formed or some substances
seem to disappear completely. These changes are called chemical changes.
Other changes to substances are physical changes.
Question: How are chemical and physical changes
important during every day activities like cooking.
Background Information
Some examples of ways that food is physically changed during cooking are
chopping things like carrots, dissolving substances like salt and sugar into the
water, melting substances like butter, and flattening substances like when dough
is rolled.
In each of these situations, the appearance, phase, or size of the substance
changes, but the composition of it remained unchanged.
When ingredients are mixed together and heat is applied, the chemical
composition of the ingredients often changes. Some examples of this are
caramelizing onions, baking bread, fermenting sauerkraut, toasting bread, and
cooking meat.
Predict Results
You will be making a S’more, by roasting a marshmallow, and placing it on a
graham cracker with a piece of chocolate.
Hypothesis: If heat is applied to a marshmallow,
then ________________________________________
____________________________________________.
(think about how the heat affects both the marshmallow and the chocolate.)
Experiment
Procedures:
1.
Break your graham cracker in half. Place
the two halves on a paper towel.
2.
Place the chocolate on one half of the
graham cracker.
3.
Place your marshmallow on the sharpened
end of a wooden skewer that has been
soaking in water.
4.
Roast your marshmallow over the butane
burner. Be careful not to set the skewer
on fire.
5.
When you are happy with your
marshmallow, place it on top of the
chocolate. Place the other half of the
graham cracker on top of it, and use it to
hold the marshmallow in place while you
remove the skewer.
Record & Analyze Data
Ingredient
Change that occurs
Graham Cracker
Broken in half
Placed on skewer
Got warmer and puffed up
Marshmallow
Turned brown
“Black Stuff” formed
Chocolate
Melted
Crushed with teeth
Entire S’more
Digested
Type of reaction
Draw a conclusion
Conclusion:
1.
2.
3.
4.
5.
List three indications that a chemical change has
taken place while roasting the marshmallow.
What “new substance” was formed on your
marshmallow when you roasted it?
What happened to the chocolate when you put
your roasted marshmallow on it? Explain.
Why did the marshmallow puff up when you
heated it?
Is roasting a marshmallow an endothermic or
exothermic reaction? Explain your reasoning.
Errors & Extensions
Errors & New Questions:
Systemic Errors:
Random Errors:
New Questions: