Grade 10 English Unit 5 Science and Experiment || Yes, You Can Boil Water at Room Temperature

 

Grade 10 English Unit 5 Science and Experiment || Yes, You Can Boil Water at Room Temperature

Yes, You Can Boil Water at Room Temperature

 

Sometimes it's right on the box of rice mix-the high altitude version of cooking instructions. Usually this means that your rice will have to cook a little bit longer if you are in Denver or at the top of Mount Everest. Of course that's just a joke. No one cooks rice at the top of Everest. But why are the instructions even different? Why does it matter where you cook? The answer has to do with boiling water.

 

You ask some people on the street about the boiling temperature of water. Some might say 212°F or even better 100°C-but that's not always true. As you increase your altitude above sea level, the boiling point of water decreases by about 1°F for every 500 feet increase. That means your water in Denver is going to be 203°F and this will have an impact on your cooking. But why?

 

Water Vapour Pressure

 

There are many awesome things about water-one interesting factoid is that on the surface of the Earth you can find water in all three phases: solid. liquid, and as a gas. We call the gas phase of wa- ter 'water vapour'.

 

You might think that you need to boil liquid water to create water vapour-but you do not. You just need some liquid water at room temperature. Picture a glass of water. If you could zoom in with super vision (not actually possible), you would see that this water is made of a bunch of molecules-water molecules. Although these molecules are themselves made of three atoms: two hydrogens and one oxygen. Let's just think of them as tiny balls.

 

These tiny water balls are moving around in the water but stay fairly close to their ball neighbours. This motion isn't due to currents in the water, instead this is thermal motion. Imagine these tiny balls jiggling around in a giant collection of balls: The hotter the water. the greater the motion of these water balls. But wait! The speeds of the water particles are not all the same. Although there is an average ball speed, some are going faster and some are going slower. It's just like the height of a group of adult humans. There is an average height, but everyone is not the same. Some people are very tall, but that's just a small fraction of the total group.

 

If you have a glass of water sitting out on a table, the water balls don't just stay as a liquid. Some of these balls have enough thermal energy to break away and become free. Free from the liquid stage means the water ball is now a gas-water vapour. Boiling is not needed to get this water vapour. But wait! It works the other way too. Some of the water balls in the gas stage can interact with the liquid water and join the liquid water balls.

Water in a closed container will eventually reach an equilibrium state between water vapour and liquid water. At this equilibrium state the rate that water balls are freed from the liquid state are the same as the rate of water balls entering the liquid state. The pressure of this water gas in equi- librium is called the vapour pressure. You can see evidence of this water vapour in a closed container by looking at the water that condenses on the walls.

 

Boiling Water

Here is what water looks like when you get it to 100°C in slow motion. Yes, I know you have seen this before. But it's still cool.

What are the bubbles in the boiling water made of?

Are the bubbles made of air? What about some hydrogen and some oxygen? No. The bubbles are water vapour-they are small pockets of water in the gas phase. I mean, they could not be air. Where would this air come from? The only option is that the bubbles are made of water vapour. So, what is happening to make these boiling bubbles of water vapour? It's all about temperature and vapour pressure. As the temperature of the water increases, the average speed of the water particles also increases. At some point, water molecules have enough energy to push back other water molecules in the liquid phase to form a bubble. But you have to have the water hot enough so that the particles are moving fast enough.

 

But wait! It is also about the vapour pressure. In order to keep the bubble from collapsing, the pressure inside the bubble must be equal to the pressure outside the bubble. Inside the bubble is the vapour pressure and outside is the water pressure. This means that for water to boil, the temperature must increase until the vapour pressure is equal to the outside pressure and a bubble can form.

 

What about that external pressure? That depends on two things. First, the water itself. In order for the water not to collapse, the deeper water must have a higher pressure. So, the water pressure depends on the depth, the density of water and the gravitational field. For a typical glass of water, the pressure at two centimetres below the surface is only a 0.2 percent increase over the atmospheric pressure. And that is the second thing that contributes to the total pressure the atmosphere. The atmosphere also pushes down on the surface of the liquid to increase the pressure in the liquid.

 

Lower Pressure

 

What if I decreased the atmospheric pressure pushing on some liquid water? This would reduce the pressure in the liquid also. If I reduce this pressure enough, I can bring it down to the same level as the vapour pressure. Boom. Now the water particles have enough energy to form their tiny little boiling bubbles-without the need to increase the temperature.

 

I can even get water to boil at room temperature. Yes, you need a vacuum pump and a strong container to get this to work-but you can do it.

Notice that I hold onto the boiling water flask just to prove that it's not hot. Trust me. Oh wait. You don't have to trust me. You can do this on your own. You just need one of these large plastic syringes. Get the syringe and put some water in it with very little air. Now seal up the end and heat up the water just a little bit. Here you can see my version.

I used hot glue and a rubber stopper (along with a Lego piece) to seal the hole. The syringe was then heated to about 42°C (a little over 100°F).

 

Now I can pull the plunger out to decrease the pressure in the liquid and induce boiling.

 

It is pretty tough to pull the plunger back to decrease the pressure- but you can do it. Oh, why heat the water up? Well. I can not get a perfect vacuum by pulling the plunger, so I need a little boiling help by starting the water at a higher temperature.

This is exactly what's going on when you cook your rice at high altitude. Well, not exactly the same-there is not a human pull- ing back on a giant plunger that holds the air on Earth. The Earth's gravitational field does that for you.

-Rhett Allain

 

 

 

 

 

 

 

 

Glossary:

altitude: the height of an object or point in relation to sea level or ground level.

Denver: a city in the state of Colorado in the United States, located at an altitude of about 1600 meters above sea level.

temperature: a measure of the degree of hotness or coldness of a body or environment.

factoid: a piece of unreliable information that is repeated so often that it is accepted as the fact.

vapour: a substance in the gas phase at a temperature lower than its critical temperature.

molecules: the smallest particle of a substance that has all the properties of that substance, consisting of one or more atoms held together by chemical bonds.

fairly: to a moderate degree; moderately; tolerably.

thermal: relating to heat or temperature.

jiggling: the rapid and irregular movement of small particles, such as molecules, caused by thermal agitation.

equilibrium: a state in which opposing forces or influences are balanced.

vacuum: a space or container from which the air or other gas has been entirely or partially removed.

plunger: a device that is used to remove blockages from the drain of a basin or tub.

induce: to bring about or give rise to.

 

A. Find the words from the text that have the following meanings.

a. the height of an object or point in relation to sea level or ground level- altitude

b. a group of atoms bonded together- molecule

c. a state in which opposing forces are balanced - equilibrium

d. to change from a gas or vapour to a liquid - condense

e. a piece of unreliable information that is repeated so often that it is accepted as the fact- factiod

f. a space or container from which the air has been removed - vacuum

g. a device that is used to remove blockages from the drain of a basin or tub - plunger

 

 

B. Complete the sentences with the correct words or phrases from the text.

a. Water bubbles breakdown if vapour pressure inside and outside the bubbles is equal.

b. As the altitude goes up, the boiling point of water decreases

c. Random motion of molecules or particles is called thermal motion

d. If the door does not open, try jiggling the key in the lock.

e. Certain chemicals can induce undesirable changes in the nervous system.

 

C. Answer these questions.

a. What is the speed of the water particles compared with?

The speed of water particles is compared with the temperature of the water.

 

b. How are bubbles formed in the boiling water?

Bubbles are formed in the boiling water due to the vaporization of water particles that become trapped in small pockets of air.

 

c. Mention two things on which external pressure depends.

External pressure depends on the mass of the atmosphere and  depth, density and the gravitational field.

 

d. How is the atmosphere related to the pressure of water?

The atmospheric pressure affects the pressure of water by applying a force on the surface of the water.

 

e. What would happen if the atmospheric pressure on the liquid water was decreased?

If the atmospheric pressure on the liquid water was decreased, the boiling point of water would decrease, causing it to boil at a lower temperature.

 

f. What would the experimenter gain if s/he pulled the plunger out?

If the experimenter pulled the plunger out, it would create a vacuum in the container, causing the water to boil at a lower temperature due to the decrease in pressure.

 

D. What would happen on the Earth if there were no gravity? Discuss possibilites with your friends.

If there were no gravity on Earth, everything that is currently held down by gravity would float off into space. This would include all living things, buildings, vehicles, and even the oceans. The Earth would essentially be a massive floating ball of matter in space, with nothing holding it together.

 

The lack of gravity would have a significant impact on the human body. Without gravity, bones and muscles would not need to work as hard to support the body's weight, leading to loss of bone density and muscle atrophy. In addition, blood would not be able to flow properly without gravity, which could lead to cardiovascular problems.

 

The lack of gravity would also affect the Earth's atmosphere. Without gravity to hold it in place, the atmosphere would gradually escape into space. This would make it impossible for humans and other living things to survive without artificial means of generating air and other resources.

 

Finally, without gravity, the Earth's orbit around the Sun would be affected, potentially leading to a catastrophic collision with another planet or celestial body.

 

If there were no gravity on Earth, the consequences would be severe and wide-ranging. The lack of gravity would affect all aspects of life on Earth, from human health to the environment and beyond.