Author: pcbpedia

Can Mass Be Negative?

Mass is defined as the amount of matter in a substance. What we measure on a weighing scale is our mass. But, can we have negative mass?

Before I dive deeper into this topic, let me explain why mass theoretically can’t be negative. This is because mass is a scalar quantity.

A scalar quantity is a quantity which has only magnitude and no direction. For example, temperature, time, area, density etc. Imagine someone saying, ” The temperature is 38°C North today!” It wouldn’t really make sense! So, scalars don’t have direction and are either positive or zero.

On the other hand, vector quantities like force, momentum, pressure etc. have both magnitude and direction. They can be positive, negative and zero.

So, you might have concluded that mass cannot be negative. But that is not true. Proving the impossible is what science does and it has done just that. Presenting- Negative mass!!

Negative mass has properties exactly opposite to that of positive mass. For example, when it is pushed in one direction, it moves in the other! So, what would happen if we used negative mass in building stuff? (Disclaimer: From here, my thoughts have been presented.)

It would probably float in the air!! We can’t really tell what will happen because negative mass is still something very weird. Imagine this scenario: A friend of yours has a mass of 50kg. If you (somehow) remove the 50kg mass from him, he would be mass-less (It is a different thing that he would cease to exist!!)! Now, if you remove something more from ‘him’, he would have negative mass. But, how can you remove something from him when there is nothing left?! Tricky questions right?

Scientist have managed to create negative mass in the form of a black fluid with the help of Rubidium (Rb) atoms. So, the concept is not entirely wacky!!

So, how was it? Did it make you rush to the weighing scale to check your mass? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati

What’s Next…?

Hello readers. If you have kept up with my posts, you might have noticed that my posts are in the order- Physics, Chemistry, Biology.

Next up is Physics. You’re going to see a very interesting topic. It would be more of my theory than proved facts as I wanted to share what I feel.

Stay tuned for this next post… This Children’s Day…

Author: Venkata Bhamidipati

How Do We Sense Light With Closed Eyes?

Even while asleep, we are somehow able to sense the presence and absence of light. But, we are taught that eyes help us to sense light. So, how do we sense light without using our eyes?

Firstly, let us understand how the eye works in the normal situation i.e. when our eyes are open. Light enters through our cornea and is refracted (bent) so that it passes through the pupil. The amount of light which passes is adjusted by the iris (scientifically called “accommodation of eye”) to create a clear picture. Light then passes through the lens, which focuses the light on the retina. The nerve cells present in the ten layers of retina interpret the message, convert the light into electric impulses, send it to the optic nerve and ultimately to the brain.

Our eye is covered by our eyelid. However, our eyelid is not totally opaque. It has slight perforations (pores) which allow light to pass through even though we close our eyes.

So, how was it? Did it “open your eyes”? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati

Source of picture: Medical News Today

Why Do Substances Sublime?

Dry Ice ( Solid CO2 ) subliming

Almost everyone of us must have experienced the phenomenon of sublimation, be it the disappearing case of naphthalene balls without a trace or the magical effects of dry ice in a theatrical performance. Sublimation is defined as the conversion of a substance from its solid state to its gaseous state without passing through the liquid phase. But, why do substances sublime?

Before I answer this, let me give you a brief background. To convert any substance from one state to another, two factors play a pivotal role: temperature and pressure. If temperature is increased, state change happens from solid to liquid to gas but if pressure is increased, state change happens from gas to liquid to solid.

For this discussion, let us consider dry ice (solid CO2 ). Carbon dioxide exists in its solid state at -78.5°C, which is way below that of water (0°C). At STP (Standard Temperature and Pressure), carbon dioxide exists as a gas.

I would like to clear one thing here- Liquid CO2 DOES exist. The only factor that makes it impossible to naturally obtain liquid CO2 is pressure. CO2 exists as a liquid at a pressure condition of 5.1 atm (atmospheric pressure) and temperature between –56.6 and +31.1°C. Though the temperature can be naturally obtained on Earth, the pressure of 5.1 atm is impossible to obtain naturally. The Earth’s atmospheric pressure is 1 atm. So, to obtain liquid carbon dioxide, we need to quintuple the atmospheric pressure! That wouldn’t be the best thing to do as it would affect all organisms adversely.

Similarly, any sublimable substance (ammonium chloride, naphthalene, camphor, iodine) would not be able to exist in liquid form due to unfavourable pressure conditions (naturally, that is).

So, how was it? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati

Source Of Picture: Wikipedia

 

Why Black Absorbs Light And White Reflects Light?

How many of you have wondered why black absorbs light and white reflects light? Actually, that isn’t how it works.

Black doesn’t absorb light. In reality, what absorbs all the wavelengths of light (abbreviated as VIBGYOR) appears black (I suppose you got what I meant). Also, black is not a colour. Black is the absence of colour.

Similarly, white doesn’t reflect light. What reflects light is white in colour and the reflection of all wavelengths of light makes an object appear white.

Consider this fact. If you take a black object and subject it to a certain wavelength of light except visible light, it would appear white! So, an important conclusion here is that an object appears black only if it absorbs “visible light” [light between the wavelengths 4 x 10 -7 m (violet) to 7 x 10-7 (red)] and appears white if it reflects visible light.

Now, we come to the other topic of discussion- How can something absorb or reflect light? Whenever light falls on any object, the object only absorbs the light if it possesses energy equal to the difference of the energies in two successive shells of an atom (ΔE). If it is more or less, the light will either be reflected or transmitted through the object.

In absorption, the light energy is converted to heat energy (That is why a black object heats up when exposed to light) and in reflection, light is bounced back from the object when the atoms in it vibrate.

However, there is one more case. Light can be transmitted through the substance.The atoms absorb the light energy for a very short duration of time and then release it to the neighbouring atom. I have already talked about this in my article “How Light Passes Through Glass?”.

So, how was it? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati

Source Of Picture: https://www.photovideoedu.com/Learn/Articles/the-color-of-light.aspx

Why Do We Get Goosebumps?

(Source of Picture: Wikipedia)

When was the last time you saw something that scared the life out of you? You must have also observed that your skin hair stands up during such a moment. This phenomenon is generally referred to as goosebumps or, in more scientific terms, piloerection. So, why does this happen?

Goosebumps are caused due to a hormone in our body known as adrenaline, which is secreted by a gland (a specialized group of cells) called the adrenal gland, located on our kidneys. A hormone is basically a chemical substance which brings about certain changes in our body. So, what exactly does adrenaline do?

Adrenaline is secreted only when we experience emotions like fear, surprise etc. or when the temperature of our surroundings or body is less. So, when one experiences such emotions, the kidneys secrete adrenaline into our bloodstream. The hormone then shows its effects.

Adrenaline causes increased heart rate, profuse sweating, and rapid breathing to name a few. But, one important function of this hormone, which is of relevance to this article, is that it reduces blood flow to our skin and digestive system. So, how does that cause goosebumps?

One of the many functions of blood is to maintain our body’s temperature. When blood flow is reduced to our skin, our skin becomes cold. This, inturn, makes our skin hair stand up and give us goosebumps. Additionally, our muscles contract due to lower temperatures, giving our skin a bumpy look.

So, how was it? Did it give you a “hairy” insight about goosebumps? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati

Can Two Elements Be Equally Reactive?

(Source of Picture: PubChem)

It is a known fact that every element on the periodic table is reactive (only excluding some of the noble gases and noble metals). But, can two metals be equally reactive?

Instead of going all theory, let us consider an example. Suppose there are two elements X and Y. X is in its free state while Y is in the form of a sulphate, say YSO4. Let us assume both X and Y to be equally reactive. So, what would happen to the reaction?

Let me brush up some chemistry facts right now. Firstly, let us depict the reaction as follows:

If X is more reactive than Y, the products of the reaction would be XSO4 + Y. But, if Y is more reactive than X, no reaction will take place.

Now, to the main point. In reality, it is not possible for two elements to be equally reactive. This fact is explained below.

We all know that all atoms of elements have electrons revolving around the nucleus. The fact of the matter is that all atoms have different amount of electrons i.e. no two atoms have the same number of electrons (We exclude isoelectronic species). But, one might also say that only the valence electrons (Electrons which revolve in the last shell of the atom) take part in the reaction. This is true. Furthermore, there are more than one elements having equal number of valence electrons. So, how do we resolve this dilemma?

For this, let us consider another example. Carbon and Silicon both have 4 valence electrons. So, they should be equally reactive. No! Not at all. Firstly, let us consider their atomic structures.

From this, we see that in carbon, there is only one shell before the valence shell (the shell which carries valence electrons). However, in silicon, there are two shells before the valence shells. Thus, there is a stronger force of electrostatic attraction between protons and electrons in silicon compared to carbon, making it more difficult to remove electrons in the former than the latter.

There is one more explanation to this question. We know that elements in the periodic table are arranged according to their reactivity (Reactivity reduces as one moves from left to right in the table). So, if two elements had to be equally reactive, they would have to coincide on the periodic table, which is not possible.

So, in conclusion, it is not possible for two elements to be equally reactive. However, what if an element was made to react with its own kind, like Iron (Fe) reacting with Iron (II) sulphate (FeSO4)? That’s a question for another article!!

So, how did you feel? Did you get the sudden itch to study the periodic table even more? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati