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Chemistry Feedback

by Ron Kurtus

Readers have sent in a total of 544 comments and questions on Chemistry issues. They are listed according to date.

You can read them to further your understanding of the subject.



List of most recent 15 letters

Title

Topic

Country

Why does an apple change color when cut open? General India
 
Why is nitrogen used in tires? Uses of Nitrogen USA
 
Microwaves and polar molecules Polar Molecules India
 
Define Electronegativity matter Polar Molecules Ethiopia
 
About Nitrogen Uses of Nitrogen Philippines
 
Examples of liquid non-polar compounds Polar Molecules India
 
Why is oxygen classified as non-polar? Polar Molecules Namibia
 
Use of arrow sign in chemical reaction Chemical Equations India
 
Can I used compressed nitrogen to paint a boat? Uses of Nitrogen USA
 
Solids used to obtain oxygen gas Oxygen Kenya
 
How is CO2 non-polar? Polar Molecules Namibia
 
Questions for science project Uses of Nitrogen USA
 
Correction in formula Order of Elements in a Formula USA
 
Why do nonpolar solutes tend to adhere Polar Molecules China
 
Name the following compounds General Nigeria
 

Next 15 letters

 





General

Why does an apple change color when cut open?

June 9, 2017

Question

Why apple turns into red colour after cutting into slides?

Maddakam - India (28081)

Answer

Apples start to oxidize once they are cut open. That is the reason the colour changes.

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Uses of Nitrogen

Why is nitrogen used in tires?

May 28, 2017

Question

Why is it used in tires?

Allen - USA (28064)

Answer

Air is made up of 78% nitrogen, so it is already in inflated tires. Pure nitrogen has the advantage of keeping a more stable pressure in the tires over a long run. Race cars use pure nitrogen to avoid pressure changes when the tires heat up during a race.

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Polar Molecules

Microwaves and polar molecules

March 31, 2017

Question

Why polar molecule are microwave active

saurabh - India (27975)

Answer

Microwave ovens work by causing polar molecules to spin rapidly and thus heat up the material. The wavelength of the microwave is such that its frequency or change in direction works well in causing the polar molecules to rotate. Non-polar molecules are not really affected by the microwave radiation.

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Polar Molecules

Define Electronegativity matter

December 6, 2016

Question

Define Electron Negativity matter on polarity and non polarity

Fanuel - Ethiopia (27533)

Answer

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Using the Electronegativities we can predict whether a given bond will be non-polar, polar covalent, or ionic. The greater the difference in electronegativity the more polar the bond.

See Bond Polarity and Polar vs Non-Polar Molecules for more information.

I hope that helps

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Uses of Nitrogen

About Nitrogen

August 11, 2016

Question

Nitrogen physical properties,origin,characteristics and uses?

Noel - Philippines (27203)

Answer

Read Nitrogen and Uses for Nitrogen.

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Polar Molecules

Examples of liquid non-polar compounds

July 10, 2016

Question

Example of liquid non polar compounds.

Raman - India (27142)

Answer

Oils, including vegetable oil and related products like gasoline, are the most common examples of non-polar liquids.

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Polar Molecules

Why is oxygen classified as non-polar?

June 25, 2016

Question

why oxgyen is classfied as non polar and carbon dioxide polar ?

Johannes - Namibia (27105)

Answer

Whether a molecule is polar or non-polar depends on its geometry. Oxygen exists as a molecule of two oxygen atoms. The combination balances the distribution of their electrons.

Carbon dioxide is also a non-polar gas for the same reason.

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Chemical Equations

Use of arrow sign in chemical reaction

May 16, 2016

Question

Some of the chemical reactions are represented by arrow sign and some are by equal sign. What is the difference between this two types?

Kind Regards,

Mohammad - India (27008)

Answer

If the chemical reaction mainly goes in one direction, it is represented by an arrow to indication the direction. For example C + O2 --> CO2.

Some reactions can readily go in both directions and are represented by a double arrow ( <---> ) or an equals sign.

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Uses of Nitrogen

Can I used compressed nitrogen to paint a boat?

April 29, 2016

Question

Hey there, I am Nelson from Nautiques Boat Care. My question is can I use it nitrogen as a substitute to regular air pressure when I spray the paint or gel coat to avoid moisture?

Jose - USA (26971)

Answer

Since air is made up of 80% nitrogen, using compressed nitrogen to spray the paint. Besides nitrogen and oxygen, air also includes water vapor.

However, compressed nitrogen probably would be more expensive than compressed.

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Oxygen

Solids used to obtain oxygen gas

April 27, 2016

Question

Name two solids that can be heated to obtain oxygen gas.

Engneer - Kenya (26969)

Answer

Mercuric oxide (HgO), potassium chlorate (KClO3), and sodium peroxide (Na2O2)

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Polar Molecules

How is CO2 non-polar?

April 13, 2016

Question

Why do we say Carbondioxide gas is a non-polar in terms of charges on it. It seems like oxygen has more electrons than carbon in gas. I am confused help me please.

Mweneni - Namibia (26927)

Answer

The atoms in carbon dioxide (CO2) are arranged in a line, with the oxygen atoms on the outside. This makes the distribution of charges symmetrical, making the gas molecules non-polar.

See the illustration of CO2 in Polar and Non-Polar Molecules. I hope that helps you understand the concept.

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Uses of Nitrogen

Questions for science project

April 9, 2016

Question

Hi, my name is Jennifer. I am emailing you because this is for my science class project and my subject was on nitrogen. And just wondering if you could answer at least two questions for me. Q1: Is nitrogen good or bad for you? Q2: when was nitrogen discovered for these uses? Please answer ASAP, please and thank you. Thank you for your time to email this!

Jennifer - USA (26918)

Answer

Since nitrogen makes up about 78% of the air you breathe, it certainly is not bad for you. What makes it good for you is that it makes sure you don't get too much oxygen at once.

Nitrogen is a key component of biological molecules such as proteins (which are made from amino acids, and nucleic acids. The nitrogen cycle in nature is very important.

Nitrogen was discovered by Daniel Rutherford in 1772 at Scotland.

I hope that helps. Best wishes for success in your science project.

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Order of Elements in a Formula

Correction in formula

January 28, 2016

Question

On your page regarding the order of elements in a chemical formula, you made the following statement:

"Most oxides will end in multiples of O, no matter what the alphabetical order. A good example is silicon dioxide: SO2"

However, I would just like to point out this (referring to the EXAMPLE) is wrong - I don't know if you are trying to refer to sulfur dioxide or SiO2. Just wanted to let you know so you could fix it! By the way, your page is amazing, super-informative and really helps me - thank you so much!

Shada - USA (26727)

Answer

Thanks for letting me know about that typo. I corrected the formula to be SiO2 in the Order of Elements in a Chemical Formula page.

I'm also glad the material has been useful to you.

Best wishes in your studies.

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Polar Molecules

Why do nonpolar solutes tend to adhere

January 9, 2016

Question

I have a question
Explain why two nonpolar solutes (or nonpolar groups) tend to adhere to each other in aqueous solutions

qun - China (26673)

Answer

This is known as the hydrophobic effect, where nonpolar substances to aggregate in aqueous solution and exclude water molecules. This occurs because interactions between the hydrophobic molecules enable the displaced water molecules to make hydrogen bonds more freely with each other and increase the number of hydrogen bonds they are involved with, thereby decreasing the overall free energy.

I hope that answers your question.

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General

Name the following compounds

December 6, 2015

Question

what is the Iupac name of the following compounds
(NH4)2SO4.Fe2(SO4)3.24H2O,
(NH4)2SO4.Al2(SO4)3.24H2O,
K2SO4.Cr2(SO4)3.24H2O.

Musa - Nigeria (26591)

Answer

I am sorry, but I do not have that information.

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