r/AskChemistry

Hi everyone,

I am currently working on synthesizing polyacrylamide (PAM) in our lab via semi-batch solution polymerization (monomer dropping method) and ran into an issue with an amphoteric formulation.

We successfully synthesized individual anionic and cationic PAMs previously:

• Anionic: Acrylamide (AM) + Methacrylic Acid (MAA) -> Success
• Cationic: Acrylamide (AM) + Acryloyloxyethyltrimethyl ammonium chloride (DAC) -> Success

However, when we tried to synthesize an amphoteric PAM using a premix of all three monomers, we failed.

Our Method:

We prepared a monomer premix of AM, MAA, and DAC, and dropped it into water containing the initiator.

Approximate Formulation (by weight):

• Water: 64%
• Acrylamide (50% aq. soln): 32%
• MAA: 1%
• DAC: 3%

The Problem:

Upon analyzing the final polymer, the anionic functionality (MAA) was practically undetectable, and the cationic charge density (DAC) was much lower than our theoretical estimates.

Question 1: Why is the amphoteric synthesis failing like this? Could it be due to the drastically different reactivity ratios between MAA and DAC when mixed together, or perhaps the formation of an ionic monomer complex (monomer pair) in the premix that alters the polymerization kinetics? What should I adjust (e.g., pH, dropping sequence, or alternative monomers) to fix this?

Additional Observation & Question 2 (Blending vs. Co-polymerization):

When we physically blended our pure cationic PAM and anionic PAM together in solution to check the charge, the solution turned highly turbid/opaque (white haze), though both charges were detected. We assume this turbidity is due to the formation of a polyelectrolyte complex (PEC).

Interestingly, we have a commercial amphoteric PAM benchmark sample from a supplier. It is not clear/transparent; it is a turbid, viscous liquid (suspension/emulsion-like appearance).

Question 2: Given that our pure copolymer blend turned turbid, is it possible that this commercial "amphoteric" sample is actually just a physical blend of anionic and cationic PAMs rather than a true copolymer? Or is it normal for a true amphoteric PAM copolymer to be turbid in solution due to intra/inter-molecular salt-and-pepper interactions?

Would love to hear insights from polymer engineers or anyone experienced with water-soluble polymers/flocculants. Thanks in advance!

Background: Grade 11 student who recently got introduced to s, p, d, f orbitals (so simplicity would be appreciated)

So according to my understanding, any orbital can only contain a maximum of 2 electrons of opposite spins due to the Pauli exclusion principle. However, when one pi-bond is formed, the y or z p-orbitals in two atoms overlap in the space above and below the previously-formed sigma bond.

My question: if one pi bond only contains two electrons and two p-orbitals were used to create the bond, there seems to be a deficit of two electrons since we started with four electrons and ended with two. Where do those two electrons that are not involved in the pi bond go, and how do they behave? Surely, they can't be in the same space as the new pi-bond orbital due to electron repulsion.

I learned that I will be required to take an ACS-style multiple choice exam for each of the five major subfields of chemistry. I only need to pass 3/5, with the cutoff being defined only as the 25th percentile, or roughly 50-60% correct answers. I know I’m not particularly unprepared for these, but as I type this I can feel my good old friend imposter syndrome budding again.

Does anyone have any recommendations for preparing for diagnostic exams of this sort? Does the feeling that you don’t really know anything ever go away, or can I expect to become more enlightened to how much I don’t know as I learn more?

Nothing crazy here but traditionally, phosphorus for turf grass comes in phosphates and phosphite, both doing drastically different things, phosphate being the one that has value nutritionally and represented as the middle number in fertilizer. Phosphite is used as a way to stimulate the plants stress responses.

I'm looking at a fertilizer label with a 0-30-30 analysis, 30% phosphate, and 30% potassium.

My question stems from this, the product is derived from only potassium phosphite, (phosphoric acid nutralized with potassium hydroxide). How can it contain any phosphate, if it's only derived from source is potassium phosphite.

Additionally I have a separate product, labeled 0-0-26 that also is derived from potassium phosphite.

Since phosphite is not metabolized by the plant, it is not used in labeling for any P content.

Is it possible the label I'm looking at is wrong and it should be a 0-0-30 instead of a 0-30-30?

Or can they partially react phosphoric acid to get some phosphite and some phosphate.

Thanks for taking the time to read my wall of text, I grow grass, not sit in a chemistry lab, but this one stuck out at me

Carbonated mineral water that has been shaken and vented to make it flat.

"No, electrons do not decay over time. [1]

Because the electron is a fundamental particle with no known internal structure, it cannot "fall apart" or split into smaller pieces. Under the laws of physics, particularly the conservation of electric charge, an electron is a completely stable particle."

"In physics, a completely stable particle is a subatomic particle that never spontaneously decays into other particles. Because it is in the lowest possible energy state, it has an infinite lifespan and persists indefinitely unless destroyed by an external force (such as encountering its antiparticle)."

Whats the take on this? Bismuth 209 has a half life older than the universe. I am wondering about the nature of the electron though. Thanks for your feedback. Cheers

I want to pursue a career in material science/nanotechnology but i am not sure about what major to choose for my ug studies. I have heard that chemistry graduates can opt for material science in their masters course. So, should i choose chemistry as my major or material science and engineering as extremely few unis offer material science and engineering as an ug major?

Also, will i need a phd or is a masters enough for a good job?

If i do choose to get a phd, what are its perks over just a masters degree

I am a graduate student in a new lab. Our lab is attempting to grow an anaerobic bacterial species, and I've had nothing but issues. I do not believe the seal between the top and bottom portions of the box is being maintained properly. The box is a Plas Labs basic glove box and has the two components mentioned above. Both the professor and I attempted to open the box and break the seal at one point to clean the inside prior to use but thought we failed. I am unable to find any information on ordering additional sealant, or what material can be used to seal the pieces of the glove box. Any assistance or experience would be helpful.

Abit of a philosophical question here but my favorite natural science so far are chemistry and physics so I want it addressed here. How do we account for change? Parmenides the Eleatic asserted that "Change Is An Illusion". Chemically speaking is that true?

Lavoisier - The famous quote, "Nothing is lost, nothing is created, everything is transformed," summarizes French chemist Antoine Lavoisier's Law of Conservation of Mass, first definitively formulated in his 1789 work, Traité élémentaire de chimie (Elementary Treatise of Chemistry)

Leucippus - Leucippus apparently formulated this position in response to the Eleatic claim that ‘what is’ must be one and unchanging, because any assertion of differentiation or change within ‘what is’ involves the assertion of ‘what is not,’ an unintelligible concept. While Parmenides' argument is difficult to interpret, he was understood in antiquity to have forced philosophers after him to explain how change is possible without supposing that something comes from ‘what is not,’ i.e. nothing. Aristotle tells us that Leucippus tried to formulate a theory that is consistent with the evidence of the senses that change and motion and a multiplicity of things exists in the world (DK 67A7). In the atomist system, change only occurs at the level of appearances: the real constituents of being persist unchanged, merely rearranging themselves into new combinations that form the world of appearance. Like Parmenidean Being, the atoms cannot change or disintegrate into ‘what is not’ and each is a solid unit; nonetheless, the combinations of atoms that form the world of appearance continually alter. Aristotle cites an analogy to the letters of the alphabet, which can produce a multitude of different words from a few elements in combinations; the differences all stem from the shape (schêma) of the letters, as A differs from N; by their arrangement (taxis), as AN differs from NA; and by their positional orientation (thesis), as N differs from Z (DK 67A6).

So chemically speaking are Lavoisier and Leucippus both correct? Change is an illusion and in reality it is just re-arrangement of atoms? However this introduces a funny if not outright false notion. If change is an illusion then energy is also an illusion. Energy being defined as the capacity to do work or produce change. If energy and change are intertwined how do we account for the atomist / chemical view of atomic combination and re-arrangement as the ultimate reality?

You know you have one. We all sniff solvents in the chemical store room.

My favorite is toluene. It smells kind of floral to me.

What about everyone else?

Why can substances/compounds like wood/gasoline act as fuel to a fire, while others like plastic/bulk iron can't?

It's job is to help stuff NOT stick.

I'm in highschool chemistry and I know how to convert it to Kelvin but I don't understand what purpose it serves.

According to Etymology it seems to be the case

Source - https://en.wikipedia.org/wiki/Etymology_of_chemistry

"The word chemistry derives from the word alchemy, which is found in various forms in European languages.

The word alchemy itself derives from the Arabic word al-kīmiyāʾ (الكيمياء), wherein al- is the definite article 'the'. The ultimate origin of the word is uncertain,^([1]) but the Arabic term kīmiyāʾ (كيمياء) is likely derived from either the Ancient Greek word khēmeia (χημεία) or the similar khēmia (χημία).^([2])^([3])

The Greek term khēmeia, meaning 'cast together',^([4]) may refer to the art of alloying metals, from root words χύμα (khúma, 'fluid') and χέω (khéō, 'I pour').^([5]) Alternatively, khēmia may be derived from the ancient Egyptian name of Egypt, khem, khm, khame, or khmi, meaning 'blackness', likely in reference to the rich dark soil of the Nile river valley."

So what is the consensus amongst chemists on this?