chapter 3

SINK

AND FLOAT

Put a large marshmallow in a bowl of water. Push down on it. Do you feel the water pushing the marshmallow back up? When you let go, the marshmallow will pop to the surface. Now drop a Jolly Rancher in a bowl of water. It sinks straight to the bottom.

The marshmallow weighs a little bit more than the Jolly Rancher. So why does the Jolly Rancher sink and the marshmallow float?

A marshmallow is full of air bubbles, which make it bigger. Because the marshmallow is so big, it pushes away a lot of water when it starts to sink. All that water pushes back. The marshmallow floats.

The Jolly Rancher weighs almost as much as the marshmallow, but it’s smaller. This means it is denser. It can’t push aside as much water as the marshmallow, so the water doesn’t push back as much. The Jolly Rancher sinks.

In this chapter, you’ll sink and float all kinds of candy. Then learn how to float the unfloatable and sink the unsinkable!

Time: 10 minutes

Skill Level: Advanced

Why does some candy sink, while some candy floats? To learn why a piece of candy sinks or floats, try this.

What you need:

Small cup or bowl, such as a ⅛-cup or ¼-cup measure, filled with water

Kitchen scale that measures grams

Pencil and paper

Tootsie Rolls, AirHeads, Laffy Taffy, taffy, or other soft candy you can squash

Large bowl of water

What to do:

1 Weigh the container of water and write down the weight.

2 Empty the container and dry it out.

3 Roll the candy between your palms to warm and soften it.

4 Squash the candy into the container until the container is full. Make sure there are no air pockets (empty spaces) between the candy and the container.

5 Weigh the container of candy and write down the weight.

6 Compare the weights. Does the candy weigh more than the water, or less? If it weighs more, it should sink in water.

7 Take the candy out of the container. (You may need to slide a table knife around the edge of the cup to unstick the candy.) Drop the candy into the large bowl of water. Did it sink? Were your calculations right?

Taffy weighs more than water. It is denser.

What’s happening:

To find out whether a piece of candy will float, you need to know how much it weighs, and you need to know how much space it takes up (its volume). This tells you how dense the candy is. If ⅛ cup of candy weighs more than ⅛ cup of water, the candy is denser than the water. It will sink. If ⅛ cup of candy weighs less than ⅛ cup of water, it will float.

more fun

If you want to test the density of your candy, find a clear 2-cup liquid measuring cup. Weigh the empty cup. Then add water to reach the 1-cup measuring line. Weigh it, and subtract the weight of the empty cup to find the weight of the water.

Now add candy to the cup until the water reaches the 2-cup measuring line. If your candy floats, you will need to push it in until it is just below the waterline. Weigh it again, and subtract the previous weight. This will tell you how much your candy weighs. Does the candy weigh more or less than the water?

If you don’t have enough candy to fill the cup, add enough candy to raise the water to the 1¼-cup line. Find the weight of the candy, and multiply that number by 4 to compare it with the weight of the water.

One cup of Warheads (340 g) is denser than one cup of water.

Time: 1 to 5 minutes

Skill Level: Easy

Advertisements for 3 Musketeers bars say they’re “light and fluffy.” How light are they?

What you need:

3 Musketeers bar

Bowl of water big enough to hold the 3 Musketeers bar

What to do:

1 Drop 3 Musketeers bar into the water. Does it sink or float?

2 Break the candy bar in half. Do you see air bubbles inside the fluffy filling?

3 Put the candy bar halves back in the water. After a little while, they should sink. Can you see air bubbles escaping?

What’s happening:

3 Musketeers bars are light because they’re full of air bubbles. The air bubbles make the 3 Musketeers bar less dense than regular chocolate, so the candy bar floats.

Air bubbles inside a 3 Musketeers bar help it float.

Floating 3 Musketeers bar.

more fun

Other kinds of candy, such as marshmallows, Twix bars, or Whoppers, also have air trapped inside. Can you find more candy that floats?

Time: 5 minutes

Skill Level: Medium

If you drop a piece of taffy in water, it sinks like a rock. Can you make taffy float?

What you need:

Several pieces of taffy or other chewy candy, such as Laffy Taffy, Starburst, or Tootsie Rolls

Small bowl of water

What to do:

1 Drop one piece of taffy into the water. Does it sink?

2 Flatten another piece of taffy. Try pressing it between your hands, pushing on it with the back of a spoon, or using a rolling pin.

3 Mold the candy into the shape of a bowl or boat. Don’t poke holes in it!

4 Gently place the candy in the water. Does it float?

What’s happening:

A piece of candy floats when it pushes aside more water than it weighs. A square or ball of taffy doesn’t push aside much water, so it sinks. But when you turn that taffy into a bowl, it can push aside enough water to float. You’ve made a taffy boat!

A large ship floats for this same reason. Even a ship made from metal, which is heavy, can push aside enough water to float.

These taffy boats float in water.

more fun

Having trouble floating your taffy? Try using foil, such as foil candy wrappers or aluminum foil, instead of candy. Crumple one piece of foil into a ball, and shape another piece into a bowl or boat. Which one floats? Which one sinks?

Time: 5 minutes

Skill Level: Easy

Most candy sinks in water. Is there a way to float the unfloatable?

What you need:

2 cups

Regular soda (not sugar-free)

Water

2 pieces Laffy Taffy, or 2 mini Snickers, Nestlé Crunch, or Milky Way bars

What to do:

1 Fill one cup with soda and the other cup with water.

2 Drop one piece of candy in the soda and another piece in the water. Does the candy float in the soda?

What’s happening:

Soda contains carbon dioxide gas. As bubbles form on the candy, they help lift it up, making the candy float in the soda. It’s like a bubble life jacket!

Soda also contains sugar, making it denser than water. This is why some candy floats better in regular soda than in diet soda or club soda.

Laffy Taffy floating in cherry soda.

Time: 5 minutes

Skill Level: Easy

Life Savers look like life preservers, the rings that help people float in the water. Can you float Life Savers candy?

What you need:

Molasses or corn syrup

Small bowl

1 mint Life Saver

What to do:

1 Pour the molasses or corn syrup into the bowl.

2 Place the Life Saver on the surface of the molasses. Does it float?

What’s happening:

When you pour molasses or corn syrup, you see that it’s thick and heavy. Molasses and corn syrup are both very dense. Since they’re denser than Life Savers, the Life Saver floats.

Life Saver floating in molasses.

Time: 5 minutes

Skill Level: Easy

Twix bars float in water. Can you make them sink?

What you need:

2 small cups or bowls water

Cooking oil, such as vegetable oil* 2 mini twix bars

What to do:

1 Half-fill one cup with water and the other cup with oil.

2 Place a Twix bar in your cup of water. Does it float? (Some Twix bars sink because they’ve been broken or squashed. If yours sinks, just try another one.)

3 Place the other Twix bar in your cup of oil. Does it sink?

What’s happ ening:

Twix bars float in water because they’re less dense than the water (think of all those trapped air bubbles). But oil weighs less than water, making it less dense. It’s also less dense than the Twix bar. So the Twix bar sinks in oil.

 

*NOTE: Don’t pour used oil down the drain. Once you’re finished with the oil, seal it in a container, and put it in the garbage, or save it for more experiments.

Twix bars in water and in oil.

Time: 5 minutes

Skill Level: Easy

A 3 Musketeers bar floats as well as a boat. Can you sink a 3 Musketeers bar in water?

What you need:

3 Musketeers bar

Bowl of water big enough to hold the 3 Musketeers bar

What to do:

1 Drop the 3 Musketeers bar into the bowl of water. Does it float?

2 Take the candy bar out of the water.

3 Squash it into a ball.

4 Put it back in the water. Does it sink?

What’s happening:

3 Musketeers bars float because the trapped air bubbles in the filling make the candy bar big and light. It pushes aside more water than it weighs.

When you squash it, you make the candy bar smaller. Since it can’t push aside as much water, it sinks.

A squashed 3 Musketeers bar sinks in water.

Time: 5 to 10 minutes

Skill Level: Medium

Marshmallows are filled with air, which makes them float. Can you sink them?

What you need:

Mini marshmallows

Large clear bowl of water

Cornstarch

Flat surface, such as a cutting board, tabletop, or counter

Spoon (optional)

What to do:

1 Drop a marshmallow into the water. Does it sink or float?

2 Sprinkle cornstarch over your flat surface.

3 Put the marshmallow on the cornstarch and squash it. Try rolling it, smashing it down, or smashing it between your hands. The cornstarch will keep it from getting too sticky.

4 Put it in water to see if it floats. (If it sticks to your hands, scrape it off with the spoon.)

5 The more you squash the marshmallow, the lower it will float in the water. If you squash it small enough, it will sink.

6 If your marshmallow didn’t sink, grab another one and try again!

A squashed marshmallow sinks in water.

What’s happening:

When you squash the marshmallow, you make it smaller and denser. The smaller it is, the less water it can push aside, and the lower it floats. If you squash the marshmallow so small that it’s denser than water, it will sink.

more fun

Can’t sink your marshmallow? Pour a cup of cooking oil, such as vegetable oil, into a bowl, and drop in your marshmallow. Since the oil is less dense than water, the marshmallow is more likely to sink. 

If you’re a champion at sinking mini marshmallows, try sinking large marshmallows. Can you beat the challenge?

Time: 5 minutes

Skill Level: Easy

Marshmallows float in water. Can you make a marshmallow submarine that sinks?

What you need:

M&M’s

Mini marshmallows

Large clear bowl of water

What to do:

1 Push one of the M&M’s into the side of a marshmallow until it sticks. Add one more on the opposite side.

2 Drop your marshmallow submarine into the bowl of water. Does it sink?

What’s happening:

To sink a marshmallow, you have to make it denser than water. This means you either need to make the marshmallow smaller or you need to add more weight to it.

When you add M&M’s to the marshmallow, you make a submarine that’s heavy enough to sink.

This marshmallow submarine sinks in water.

more fun

Can you add enough candy to a big marshmallow to make a sinking submarine? What about a chocolate-covered marshmallow, like a pumpkin or Santa?

Time: 5 minutes

Skill Level: Easy

M&M’s, Skittles, and Jelly Belly beans sink in water—mostly. To see what floats, try this.

What you need:

M&M’s, Skittles, or Jelly Belly beans

Bowl of warm water

What to do:

1 Drop the candy into the bowl of water, logo side up.

2 Wait a few minutes. Do not stir the water.

3 After a few minutes, look for floating letters. (Some break up as they rise, but a few should survive intact.)

What’s happening:

The white letters on M&M’s, Skittles, and Jelly Belly beans are printed with an edible ink that doesn’t dissolve in water. When the rest of the candy shell dissolves, the letters peel off and float.

Floating Skittles.

Time: 1 to 2 hours

Skill Level: Easy

Conversation hearts sink. Can you make them rise?

What you need:

Conversation hearts

Small clear bowl of water

What to do:

1 Put the conversation hearts into the bowl of water.

2 Wait about 2 hours. Do the hearts start to float?

What’s happening:

The conversation hearts sink because they’re denser than water. But as they sit in the water, air in the water forms bubbles on the hearts. The bubbles help the hearts float up to the surface.

Floating conversation heart.

more fun

How do you know that it’s really the air in the water that makes the hearts float? Ask a grown-up to boil some water for you. Boiling the water will remove most of the air.

After the boiled water cools, pour some into a small bowl, pour water from the tap into a second cup, and put some hearts in each one. The hearts in the tap water will float sooner, because the tap water has more air in it.

Time: 5 minutes

Skill Level: Easy

Hearts sink, and hearts float. Can you make them do both?

What you need:

Clear drinking glass

Club soda or clear soda

Conversation hearts or Necco wafers

What to do:

1 Fill the drinking glass with soda.

2 Put the candies in the glass. Do some of them float? Do they sink again? (If they don’t sink by themselves, tap them with a spoon to knock off the bubbles.)

What’s happening:

Club soda contains carbon dioxide gas. When the carbon dioxide forms bubbles on the candies, the candies start floating. It’s as if they were wearing life jackets. But as the candies rise, the bubbles pop or get knocked off. Without the bubbles, the candies sink back to the bottom. Then bubbles start to form again, and the cycle starts over.

Brach’s conversation hearts in 7UP.

more fun

Try this experiment with raisins.