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by Ron Kurtus

A total of 250 comments and questions have been sent in. They are listed according to date.

## List of most recent 10 letters

### Country

Kinetic Theory of Matter What is a solid, liquid and gas? India

Atom as Solar System Why isn't the solar system a giant atom? USA

Density Factors How physical conditions affect density USA

Evaporation How are water molecules able to escape gravity? USA

Changing States of Matter What if matter did not change its state? Pakistan

Pressure and States of Matter Permission to use images USA

Dry Ice Using CO2 for supercritical extraction USA

Dry Ice Info on dry ice USA

Density What is the calculation of density? South Africa

Pressure and States of Matter Explain pressure in gases and liquids Nigeria

Next 10

## What is a solid, liquid and gas?

Topic: Kinetic Theory of Matter

### Question

November 7, 2017

Q1. What is solid, liquids, gas

MD - India

28313

See States of Matter for an explanation.

## Why isn't the solar system a giant atom?

Topic: Atom as Solar System

### Question

October 5, 2017

I had a question about the article you wrote regarding Bohr's Model of an atom. Why do you disagree with the fact that our solar system can't be just one "giant" atom. I was hoping to get in touch with you to discuss this?

Tristan - USA

28273

Although our solar system looks like it could be a giant atom, there are a number of problems in the analogy. One it that electrons in an atom have an electrical charge, while there is nothing similar in the solar system. Also, the nucleus of an atom is made up of protons and neutrons, while the Sun is a mass of hot gases.

On the quantum scale, atomic particles are not tiny spheres but are wave packets.

Still, the similarity between the solar systems and atoms is intriguing.

## How physical conditions affect density

Topic: Density Factors

### Question

September 30, 2017

Describe how physical conditions affect density

kiprotich - USA

28267

Density is mass divided by volume. Compressing an object decreases its volume and thus increases its density.

## How are water molecules able to escape gravity?

Topic: Evaporation

### Question

September 22, 2017

How are water molecules able to escape gravity? In other words, gravity withholds H2O from leaving the surface of the earth, but that same body of water evaporates and those molecules are unaffected by gravity.

Travis - USA

28256

With water, the velocity of the molecules is not great enough to overcome their molecular attraction, and thus the material is a liquid that is kept toward the surface of the Earth. However, when H20 becomes a gas, the velocities of the molecules is much greater, such that they move about freely.

Most of those molecules velocities that are low enough to be constrained to the Earth's atmosphere. But some of the molecules of the gas or steam become accelerated due to radiation from the Sn, such that they have enough kinetic energy or velocity to escape the Earth's gravity.

Fortunately, the loss of water vapor molecules into space it very small.

## What if matter did not change its state?

Topic: Changing States of Matter

### Question

August 25, 2017

Explain that what happened if there would be no change in states of matter?

Thanks

Aamish - Pakistan

28197

If all matter stayed in its existing state or phase, ice would not melt to become water, and water could not boil into steam. Also, there would be no evaporation of water. Just these factors alone would affect living beings in a short time.

## Permission to use images

Topic: Pressure and States of Matter

### Question

August 14, 2017

I would like to use the phase diagram figures that you have on this page: http://www.school-for-champions.com/science/matter_states_pressure.htm

in an article that I am writing for the Health Physics Society. I understand that I need permission to use the figures. Is that possible that I could have permission to use your figures?

Thanks so much,

Linda - USA

28181

Yes, you have permission to use the diagrams provided you cite the source.

Best wished for success in your article. Let me know when it is published.

## Using CO2 for supercritical extraction

Topic: Dry Ice

### Question

January 29, 2017

I would like to discuss some commercial uses for Dry Ice and it's conversion to Co2 for supercritical extraction.
Please let me know if you are available to discuss.

Gary - USA

27838

Dry ice is a convenient source of CO2. Allowing the gas from the dry ice to heat to about 31 degree C should help in the supercritical extraction process.

I hope that helps. Unfortunately, I am not an expert in this field.

Best wishes for success in your work.

## Info on dry ice

Topic: Dry Ice

### Question

March 11, 2016

To whom this may concern,

I am a sixth grader at Kennedy Middle School. Our school is participating in something called Genius Hour which allows us to research a topic that interests us. We are required to interview a professional who is knowledgeable about our topic. My topic is dry ice.
If you could please answer the questions below as soon as you get the chance, it would be greatly appreciated. Thank you for taking time out of your day to respond to this email.

Gianna G.

My questions are:

Where was dry ice first found?

How long does dry ice last in water?

What gas is given off of dry ice?

How is dry ice created?

What is inside dry ice?

How long can you touch dry ice with bare hands?

Can you make dry ice?

Gianna - USA

26856

Dry ice was first observed in 1835 in France. It is frozen carbon dioxide (CO2). When it melts, it turns to CO2 gas. You should only hold dry ice a fraction of a second. Special equipment is used to make dry ice.

See our lesson on Dry Ice is the Solid State of Carbon Dioxide for more information. Also see Dry Ice Wiki for detailed info.

Best wishes for success in your report.

## What is the calculation of density?

Topic: Density

### Question

February 23, 2016

calculation of density

sello - South Africa

26803

The density of an object is its mass divided by its volume.

Since the density of water is 1.0, you can find an object's density relative to water by comparing its weight to the weight of an equal volume of water.

## Explain pressure in gases and liquids

Topic: Pressure and States of Matter

### Question

February 16, 2016

explain vapour
pressure and explain the principles of pressure
measurement in liquid and in gases

okpu - Nigeria

26784

Vapour is the gaseous state of matter. It is like steam.

Meters can compare water or air pressure with some standard. A barometer is an example of a meter that measures air pressure.

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## Resources and references

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