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Feedback Q&A on Chemistry

by Ron Kurtus

Readers have sent in a total of 546 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 10 letters




Uses of Nitrogen Biological importance of nitrogen Algeria
Order of Elements in a Formula Azeotropic Mixture Nigeria
General Why does an apple change color when cut open? India
Uses of Nitrogen Why is nitrogen used in tires? USA
Polar Molecules Microwaves and polar molecules India
Polar Molecules Define Electronegativity matter Ethiopia
Uses of Nitrogen About Nitrogen Philippines
Polar Molecules Examples of liquid non-polar compounds India
Polar Molecules Why is oxygen classified as non-polar? Namibia
Chemical Equations Use of arrow sign in chemical reaction India

Next 10


Biological importance of nitrogen

Topic: Uses of Nitrogen


March 17, 2018

i've project under title :"Elements of the nitrogen group."
can you plaese give me the Biological importance of this elements please .
please send the answer to my email address
and thank you

sarra - Algeria



Nitrogen is a component of amino acids and urea. Amino acids are the building blocks of all proteins. Proteins comprise not only structural components such as muscle, tissue and organs, but also enzymes and hormones essential for the functioning of all living things. Urea is a byproduct of protein digestion.

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Azeotropic Mixture

Topic: Order of Elements in a Formula


October 27, 2017

Whats Azeotropic Mixture

Saviour - Nigeria



An Azeotropic Mixture is known as a constant boiling point mixture. That means the mixture cannot be separated by boiling or distillation. An example of such a mixture is 5% water and 95% ethanol.

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Why does an apple change color when cut open?

Topic: General


June 9, 2017

Why apple turns into red colour after cutting into slides?

Maddakam - India



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

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Why is nitrogen used in tires?

Topic: Uses of Nitrogen


May 28, 2017

Why is it used in tires?

Allen - USA



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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Microwaves and polar molecules

Topic: Polar Molecules


March 31, 2017

Why polar molecule are microwave active

saurabh - India



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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Define Electronegativity matter

Topic: Polar Molecules


December 6, 2016

Define Electron Negativity matter on polarity and non polarity

Fanuel - Ethiopia



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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About Nitrogen

Topic: Uses of Nitrogen


August 11, 2016

Nitrogen physical properties,origin,characteristics and uses?

Noel - Philippines



Read Nitrogen and Uses for Nitrogen.

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Examples of liquid non-polar compounds

Topic: Polar Molecules


July 10, 2016

Example of liquid non polar compounds.

Raman - India



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

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Why is oxygen classified as non-polar?

Topic: Polar Molecules


June 25, 2016

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

Johannes - Namibia



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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Use of arrow sign in chemical reaction

Topic: Chemical Equations


May 16, 2016

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



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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