How Fast?

Kitchen Chemistry · Page 1 of 5

Name Date
DIRECTIONS: For each run, pour a splash of vinegar on a spoon of baking soda and time the fizzing.
Safety first.
  1. A grown-up is in the room.
  2. Never mix cleaning products. Bleach and vinegar make a gas that hurts people.
  3. Nothing goes in your mouth, not even food.
  4. Only use what is on the list. Ask before trying anything else.
RunWaterStirred?SodaVinegarHow long it fizzed
A — the controlcoldnolumpsplain
B — warm water insteadwarmnolumpsplain
C — stirredcoldyeslumpsplain
D — crushed to powdercoldnopowderplain
E — twice as much vinegarcoldnolumpsdouble
  1. Put the five runs in order, fastest first.
    Show your work
  2. Every run except A changed one thing. Say why it had to be one — what would go wrong if run B were warm AND stirred?

Four Handles, One Idea

Kitchen Chemistry · Page 2 of 5

DIRECTIONS: Fill in the table. What do all four changes do to the pieces?
  1. Run A is called the control and nothing was changed in it. What is it for?
What you changedWhat is different about the pieces now?Faster or slower?
heat
stirring
crushing
strength
A reaction happens when pieces meet. All four handles make them meet more often: faster pieces, stirring, more outside, or more pieces in the same space.
How often do the pieces meet?

Using It On Something Else

Kitchen Chemistry · Page 3 of 5

DIRECTIONS: Name the handle for each.
  1. Bread goes stale faster on a hot day. Which handle is that, and what is happening to the pieces?
  2. A whole potato takes 45 minutes to cook and chips take 8. Which handle? Say what is different about the pieces.
  3. Here is one nobody showed you: a fire burns much better when you blow on it. Which handle is that, and what is being brought to what?
  4. Predict one of your own. Write down something in your house that would go faster if you used one of the four handles — and say which.

Running It Backwards

Kitchen Chemistry · Page 4 of 5

DIRECTIONS: Food going off is a reaction. Each trick below turns a handle backwards. Which one, and why does it work?
What people doWhich handle, backwards?Why it works
Put it in the fridge
Put it in the freezer
Keep it in a sealed jar
Keep the fruit whole instead of cut up
Pack fish in salt (people did this for centuries)
  1. The freezer does not stop food going off for ever. Using rate, say why "for ever" is the wrong word.
  2. Cut an apple in half. Leave one half out and put the other in a sealed box. Predict which goes brown first, then try it and write what happened.

Two That Explain Themselves

Kitchen Chemistry · Page 5 of 5

DIRECTIONS: Two more from your kitchen.
  1. Squeezing lemon juice on cut apple slows the browning right down. From sheet 10, what is lemon juice? Say what that tells you about this reaction.
  2. Somebody says "the fridge kills the germs". What is wrong with that, and what is it really doing?