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24
votes
5answers
15k views

Why does radium have a higher first ionisation energy than barium?

I'm wondering why radium appears to buck the general trend that first ionisation energies decrease as you move down a group in the periodic table: barium (the group 2 element preceding it) has a first ...
18
votes
5answers
12k views

Where can I find a downloadable spreadsheet of element properties?

Sorry for the FAQ, but I really don't know where to find a full spreadsheet for element properties. I mean a table that has one row for each element, and the columns are its properties, such as name, ...
1
vote
1answer
325 views

How can you explain that the ratio of the densities of Ag and Au equals the ratio of their relative masses?

My book says that silver and gold both have the same face centered cubic structure and then asks to show and explain why the ratio of their densities equals the ratio of their relative masses. How can ...
17
votes
1answer
2k views

What are the g-block's predicted properties?

I have been researching for a Physics/Chemistry exam and thought; what will the future periods in the periodic table (periods 8 and above) would entail? Each block contains its own properties that ...
10
votes
1answer
14k views

Why is the relative atomic mass of carbon not exactly 12?

Relative atomic masses of atoms of all chemical elements are numbers without units, being the value of proportion compared to $\frac{1}{12}^\text{th}$ the mass of the carbon atom. But the relative ...
2
votes
1answer
152 views

Which plastic can be partially broken by pressure easily?

I need to create a container which hold ~150 to 500 ml water. My plan is to create something like a inverse cone. I will apply pressure (~20psi) on the top of the cone and I want to create a hole at ...
0
votes
2answers
536 views

What are the common names of this two types of plastic?

I need to do some plastic molding design. I want to know the names/types of plastic which are commonly/widely used in industries (please see the pictures below).
11
votes
1answer
2k views

Resonance in carbocation derived from allenes

During a reaction if addition on one of the $\pi$ bonds of an allene (containing even number of $\pi$ bonds like $\ce {H2C=C=CH2}$) takes place then a carbocation is formed. To decide the position of ...
11
votes
2answers
1k views

How does localized bonding theory and hybridisation work?

So I understand molecular orbitals and how to do VSEPR models, but I seem to be struggling with understanding localized bonding theory and how to do hybridizations. After drawing the initial lewis ...
15
votes
2answers
4k views

Why are there quantised energy levels in the vibrational energy of a molecule?

Why are the energy levels for vibrational energy in a molecule discrete as opposed to continuous? I don't understand how a vibration can't have continuous amounts of energy that depend on the ...
4
votes
4answers
9k views

Homemade Rocket Fuel and Engine

I want to put an action figure in orbit but I need to know how to make a secure yet not too expensive rocket fuel engine. The design of the engine must very primitive and not too complicated. I've ...
19
votes
4answers
66k views

Why is salt needed when using vinegar to clean pennies?

Let's say you have a solution that is vinegar and it has salt (NaCl) dissolved in it. Then you place old dull pennies in it. Then you look at it 5 minutes later and the pennies are clean and looking ...
10
votes
4answers
9k views

Synthesis of hydrazine with bleach and ammonia

I am trying to make rocket fuel using hydrazine, hydrogen peroxide and home products. I want to put an action figure in orbit. Is there any way to synthesize hydrazine with bleach and ammonia, using $...
1
vote
1answer
2k views

Oxidization of Copper In Electrolysis

So during school today, I am running an electrolysis experiment with water and sodium bicarbonate copper leads on both the anode and cathode. I am noticing the usual $\ce{NaO}$ on the anode, and $\ce{...
4
votes
2answers
921 views

How to derive partial gas equation?

If the following gasses are to mix, what is the partial pressure of neon? The correct answer is 0.1. I cannot figure out how my professor derived this equation. From the ideal gas law, all I ...
1
vote
1answer
2k views

Synthesis of nitrocellulose

I am trying to understand the synthesis of nitrocellulose. A mixture of sulfuric acid and nitric acid is used to nitrate cellulose. The sulfuric acid acts as a catalyst, producing $\ce{NO2^{+}}$ ions ...
6
votes
2answers
362 views

Classical reason for good heat conductance in diamond?

My teacher in my physics course attributed this effect to phonons, more here, but I am skeptical about this argument, it feels like he is overlooking the whole question -- what about with Silica that ...
2
votes
1answer
235 views

How does one synthesise 2-Monoglycerides from Triglycerides?

How does one synthesise 2-monoglycerides from triglycerides with additional ingredients if necessary? My first instinct would be to add a catalyst for the reaction of $triglyceride \rightarrow 3 FA + ...
5
votes
2answers
1k views

How do you Synthesise a Fatty Acid Amide?

How would you go about synthesising a fatty acid amide, preferably by means of a high-yield reaction. Please provide an explanation that I, as a grade 12 chemistry graduate, could understand. I am ...
7
votes
1answer
917 views

Does sublimation happen only on the surface or throughout the body?

Like evaporation happens only on the surface of a liquid, and boiling/vapourisation takes place throughout the body, how does sublimation occur? Why?
4
votes
2answers
5k views

Why water can't mix with oil or cooking oil?

Why water can't mix with oil or cooking oil (both saturated and unsaturated)?
-1
votes
0answers
745 views

Homework - Ideal gas law [closed]

I don't understand how to find the volume in this problem.. A flask containing 63.2 mL of neon gas was collected over water at 21C and 788 mm Hg. What is this volume of gas at STP? (WVP at 21C = 18.6 ...
6
votes
1answer
9k views

A thermoset or a thermoplastic?

How do you know if a polymer is a thermoset or a thermoplastic? For example: hydroxybutanoic acid 2-amino-3- hydroxybutanoic acid (I am not sure if these are correct in English) I know what ...
7
votes
3answers
265 views

Has the molecular diatomic oxygen trianion been observed or predicted?

Has diatomic oxygen ever been observed with a 3− charge, i.e. $\ce{O_2^{3-}}$? Have any ab intio calculations been done on this ion? Update: Just to summarize some of the answers below and add my ...
3
votes
1answer
5k views

Hypochlorous acid mechanism

When hypochlorous acid is dissolved in water, is it the chlorine atom or the oxygen that serves as the anti microbial agent?
10
votes
2answers
2k views

Why does Naphthalene turn into needle-shaped crystals by sublimation?

I wonder why crystals of Naphthalene are needle-shaped after sublimation. Googling the fact, I could only confirm that it is true but failed to find the reason. Could someone please shed some light as ...
2
votes
2answers
102 views

Is it possible to prevent methane combining with oxygen?

The output from an anerobic kitchen waste digester is mostly $\ce{CH4}$, and $\ce{CO2}$. If the methane is collected over water; algae/moss may use the $\ce{CO2}$ to grow. Yet oxygen is released ... ...
12
votes
2answers
460 views

Why do oxidation numbers work?

I understand that oxidation numbers are a method for keeping track of electrons in a reaction and how they are generally assigned (electrons in a bond are assigned to the more electronegative atom). ...
4
votes
2answers
443 views

What are the major environmental drawbacks with using methane as a combustable fuel?

What are the biggest environmental issues with using methane, $\ce{CH4}$, (which is found as the major energy source in natural gas, shale gas, biogas, and synthetic natural gas), as a combustible ...
28
votes
1answer
565 views

How does Palladium dissociate H₂ so easily?

If I understand correctly, $\ce{H2}$ in the presence of $\ce{Pd}$ readily dissociates as it dissolves into the metal. With the dissociation energy for the $\ce{H—H}$ bond being so large, how is this ...
9
votes
1answer
406 views

Forms of carbon in incomplete combustion

When hydrocarbons burn with little oxygen, carbon is produced. What form do these particulates of carbon come in? Is it a simple molecule like $\ce{S8}$, or a small fragment of a larger structure, ...
12
votes
4answers
7k views

Is it possible to synthesise ethers from carboxylic acids?

Is it possible to synthesise ethers from carboxylic acids, and if so, how? By ether I mean an ether in general ($\ce{R-O-R'}$), not just specific examples. I theorised one could perform Fischer ...
4
votes
2answers
177 views

Correct nomenclature for reaction types

What is the correct name for a reaction like this? $$ \ce{ 4MnO2 ->[500\ ^\circ \text{C}] 2Mn2O3 + O2 ^}$$ Is it a synthesis, or a Decomposition? I tried to find it out with http://en.wikipedia....
6
votes
2answers
72k views

Why does the hydroxide ion have a negative charge?

I've been studying the roles of hydroxide & hydronium in acids and bases, and it was mentioned that a hydroxide ion (OH-) has a negative charge. Can someone give me a layman's explanation of what ...
5
votes
1answer
870 views

Are different enclosing mark types in chemical names needed to differentiate between substances?

What is the significance of enclosing marks in chemical names in determining the uniqueness of a substance (organic and inorganic)? Can a simple change in the type of enclosing mark used indicate ...
1
vote
2answers
907 views

How does 1,3-dichloro-1,3,5-triazinane-2,4,6-trione (dichloroisocyanuric acid) generate hypochlorous acid when dissolved in water?

Can someone draw the reaction that leads to the generation of HOCl when dichloroisocyanuric acid (structure shown below) is dissolved in water?
4
votes
1answer
2k views

How can I find pKa from a titration curve?

I am fully aware that the pKa is the pH at half the equivalence point, but are there some programs or methods I could use to accurately estimate the pKa without manually drawing lines on the graph?
3
votes
3answers
1k views

What are physical properties and chemical properties?

As the question title says, I would like to know what the physical and chemical properties are. If possible, please include examples. Since it seems to be related, I would also like to know what ...
6
votes
1answer
2k views

If I have a chiral substrate, should I always assume that both enantiomers are present?

Considering the Sn1 reaction of (S)-2,3-dimethyl-3-pentanol, knowing that this molecule has a chiral carbon, should I always assume that both enantiomers are present, and therefore the products of a ...
0
votes
2answers
7k views

List in order of increasing radius

List in order of increasing radius: a) Rb, K, C5, Kr For this one I got C, Kr, K, Rb b) Ar, Cs, Si, Al This I got: Ar, Si, Al, Cs Does anyone know if this is correct? I don't have the solution ...
11
votes
2answers
13k views

Why does chocolate ice cream melt faster than others?

The other day I was dipping out Neapolitan(strawberry, vanilla, & chocolate) ice cream and noticed that the chocolate ice cream tended to melt faster than that of the vanilla and strawberry. I ...
8
votes
1answer
552 views

Thiosulphate acidic decomposition

I just came across this reaction $\ce{Na2S2O3 + 2HCl -> 2NaCl + SO2 + S + H2O}$ I was wondering if it was possible to predict the products of this reaction if I didn't know it (or any inorganic ...
8
votes
1answer
1k views

Preparation of alkyl halide from alcohols

$\ce{R-OH + HBr -> R-Br + H2O}$ An $\ce{R+}$ carbocation is formed during this reaction. If $\ce{R}$ is any alkyl group instead of methyl or ethyl, can the beta hydrogen to the hydroxy group be ...
1
vote
2answers
2k views

How should I identify my leaving group in SN1 reactions if there might be more than one option?

Before I can even begin to contemplate the products of a given SN1 reaction, I need to be able to determine what my leaving group will be, which should be a species with a strong conjugate acid, and ...
7
votes
1answer
7k views

What are the products in this SN1 reaction?

I am asked to identify the organic/inorganic products of an SN1 reaction between 3-iodopentane and ethanol. I have identified correctly that the substrate is the 3-iodopentane, the leaving group is ...
9
votes
3answers
2k views

Is electrochemically activated water a real technology?

In essence what I'm asking is if the applications of Electrochemically activated water (ECA water) as a bactericidal-disinfectant is real and profitable (especially this last part). The principle at ...
2
votes
1answer
12k views

Physical state of hydronium

I am doing my chemistry homework and I am supposed to write the products when strong acids react with water, but I am unsure of the physical state for hydronium ions. Should it be liquid (l) or ...
11
votes
1answer
26k views

What's that tangy smell on cheap plastic?

Most cheap items (from China mostly) have a strong tangy odor to the plastics (or some resin, but I can mostly smell it on plastics). The smell is always consistent over a broad range or products and ...
8
votes
1answer
2k views

Simultaneous equilibria

Rephrasing: The following reactions are a small example of my big system $$(1)\ \ce{A + B <=> AB}$$ $$(2)\ \ce{AB -> CB}$$ $$(3)\ \ce{A -> C}$$ $$(4)\ \ce{C + B <=> CB}$$ with $...
16
votes
3answers
57k views

Anomalous electronic configuration of platinum

Why is the electronic configuration of platinum $$\mathrm{[Xe] 4f^{14} 5d^9 6s^1}$$ and not $\mathrm{[Xe] 4f^{14} 5d^{10} 6s^0}$ or $\mathrm{[Xe] 4f^{14} 5d^8 6s^2}$?

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