# All Questions

28,650 questions
21 views

### Half life of A in the first order reaction 2A+B-> Products [closed]

In the reaction 2A+B->Products, if Rate=k[A] and k=0.0693 then what is the time taken to consume half of A? Can someone please provide a solution to this question? Regards, Apoorv
25 views

### What metal is this???Brass patina, turned grey!

I have this piece for a long time. It has always been a brass like color. It was very dirty so I decided to clean it up. To my surprise after sanding it became grey, almost silver like color. I ...
11 views

### Correlation energy in quantum chemistry

In DFT there is classic Coulomb energy and non-classic correlation energy. But what is difference between them? In books these energies are explained very similarly. Both contributions are explained ...
43 views

### Why enthalpy is defined at a constant pressure?

How absolute enthalpy and enthalpy change are defined? What is the clear difference between enthalpy and heat? Is it the constancy of pressure what makes the enthalpy a state function? My teacher ...
25 views

### adiabatic expansion vs Joule-Thomson Effect

Source: The1stLawofThermodynamicsLesson4 I am looking for difference between adiabatic expansion and Joule-Thomson effect. Looking at the setup demonstrating Joule-Thomson effect, I find no essential ...
22 views

### Aqua complex scarcity for transition metal ions of second and third row

I've read that for the second and third row of the transition metal ions, almost no [M(OH$_2$)$_6$]$^{2+}$ or [M(OH$_2$)$_6$]$^{3+}$ complexes are known, while they're very common for the first row. ...
20 views

### Why concentration of water is not taken 1 for the equilibrium constant of esterification reaction? [on hold]

For pure liquids and pure gases, we approximate the concentrations equal to 1. In case of the esterification reaction, why do we write $\ce{H2O(l)}$ in the $K_\mathrm{c}$ formula since we have ...
20 views

### Precipitating an aqueous solution of ions

If you are provided with the aqueous solutions of the following: $\ce{NH3}$, $\ce{NaOH}$, $\ce{Na2CO3}$, dilute $\ce{HCl}$, dilute $\ce{H2SO4}$, dilute $\ce{HNO3}$ And you are required to separate ...
54 views

### Does sodium borohydride reduce C=N group?

Q.15 the major product of the following reaction is: I have read that $\ce{NaBH4}$ reduces only aldehyde, ketone and acid chlorides. In some cases it may reduce double bonds conjugated with ...
21 views

### How to find the molarity of Fe(NO3)3 in a stock solution made from multiple solutions [closed]

A stock solution will be prepared by mixing the following chemicals together: 3.0 mL of 0.00200 M KSCN 10.0 mL of 0.200 M Fe(NO3)3 17.0 mL of 0.5 M HNO3 Determine the molar concentration of Fe(NO3)3 ...
6 views

### Is Dilition formula can be used to make given solution more concentrated? [closed]

Removing the 2nd volume obtained by evaporation or adding more moles of solute,dilution furmula will be apllicable...
3k views

### Why does graphite have a high melting point even though its intermolecular forces are weak?

From what I've read online, when a substance undergoes a state change, the intermolecular forces are broken. The covalent bonds are not broken (http://www.bbc.co.uk/schools/gcsebitesize/science/...
17 views

### Some questions about electrochemistry [closed]

1) Which of the following electrodes is used as pickup electrode for measuring redox potential of the system Cr3+/Cr2+? a) glass. b) zinc. c) copper. d) platinum e) silver chloride 2)...
23 views

### Binding aqueous solution and oil solution without an emulsion

I am trying to solve this mystery...There is this company called 100% pure who makes lipsticks using fruit extracts as their pigments in their formulations. Fruits pigments are water soluble - so, the ...
31 views

### Apparent contradiction in the name of group 2 elements

From my understanding (I might be very wrong), the "earth" in alkaline earth metals means non-metallic, insolube in water and resistant to heating, therefore the oxides and hydroxides of group 2 ...
8 views

### KINETIC MOLECULAR THEORY [closed]

Part 1. A chemist reacted 18.0 liters of F2 gas with NaCl in the laboratory to form Cl2 gas and NaF. Use the ideal gas law equation to determine the mass of NaCl that reacted with F2 at 290. K and 1.5 ...
18 views

### Cheaper ionic membranes

I am trying to make sodium hydroxide by electrolyzing table salt. I learned that I need cation exchange membrane (CEM) to prevent Cl- from crossing over to the cathode. The only example of CEM that I ...
10 views

### Equilibrium Acids, Bases and salts [closed]

If the equilibrium in this equation lies far to the left, which is stronger of the two bases? explain why: CH3NH2 + NH4 = CH3NH3 + NH3
20 views

### PHASES OF MATTER : KINETIC MOLECULAR THEORY [closed]

Part 1. A glass bottle, which is half-filled with water, has a balloon attached to its opening. The bottle is placed in a hot water bath for some time. Explain the change to the size of the balloon ...
20 views

### How do you use the Nernst equation on lithium ion batteries [closed]

Anode: LiC6<=> C6 + Li+ + 1e- Cathode: Li+ + 1e- + CoO2 <=> LiCoO2 Overall: LiC6+CoO2<=>C6+LiCoO2 How do you apply the Nernst equation to this reaction? The concentration of solids is ...
15 views

### Which bond is more polar without a table of electronegativities? [closed]

In my AP chemistry book it says that you can determine which of two bonds is more polar without knowing the electronegativity if they have one atom in common. The more polar bond will be the one where ...
16 views

### Schrodinger Equation : TDSE and TISE [closed]

How can one particular Schrodinger equation be both time-dependent and time-independent at the same time? I mean its wrong by the very notion to say both simultaneously. We encounter many instances ...
23 views

### Finding magnesium aluminosilicate mineral with a sandwich structure [closed]

It is a mineral material with a sandwich structure, which contains $\ce{Mg^2+}$, $\ce{Al^3+}$ and many $\ce{Si-O}$ bonds.
14 views

### pH calculation and concentrations of all species present in a solution [closed]

When $\ce{NO2}$ is bubbled into water, it is completely converted to $\ce{HNO3}$ and $\ce{HNO2}$: $$\ce{NO2 + H2O -> HNO3 + HNO2}.$$ Calculate the $\mathrm{pH}$ and the concentrations of ...
16 views

### Can you please tell me the process? [closed]

The value of Kc=4.24 at 800K for the reaction, CO(g)+ H20(g) >CO2(g) + H2(g) Calculate the equilibrium concentrations of CO2, H2, CO and H2O at 800K, if only CO and H2O are present initially at ...
16 views

### will two weak acids lower their degree of dissociation when put together in solution compared to when put separately

When two weak acids are put in aqueous solutions separately they will have some value of degree of dissociation, now when both are put together will there be a decrease in their dissociations, I ...
26 views

### Pls help confusing [closed]

Its a chemical kinetics quedtion from jee main 2019 i got answer 10 but many places answer is 5 i thought that as reaction is first order it must be equal to half life
16 views

### How much Sodium Bicarbonate (NaHCO3) do I need to add to specific volume of water to increase the pH by specific amount? [closed]

I'm trying to increase the pH of a nutrient solution for algae I'm attempting to grow. I suspect that my algae will grow at a higher pH than contaminants. I want to raise the pH of a container of ...
38 views

### Why does this region fit NMR spectroscopy technique?

I was reading a paper and came across a sentence (highlighted one) about NMR spectroscopy. Several Leishmania Rabs, like Rab1, Rab5a, Rab5b, and Rab7, have been functionally characterized. LdRab5a ...
92 views

### How does the pH of solutions of salts in which the cation is acidic and anion basic, depend only on the relation of their constants?

My book is not very explanative about it, I'm trying to get the equation: $$[\ce{H^+}]=\sqrt{K_\mathrm{w}\times\frac{K_\mathrm{a}}{K_\mathrm{b}}}$$ but I didn't succeed, can someone explain the ...
12 views

### To find out how much urea will separate out? [closed]

I know how to solve the above question I will let water used be 'w' gm and then will apply the formula of decrease in free zing point and then calculate 'w' then it would be subtracted from 250 gm . ...
35 views

### What is the refractive index of poly(methacrylamide)?

I've been looking for the index of refraction for poly(methacrylamide). I searched several vendors and in https://polymerdatabase.com/ with no success. Is there any database where I can find this ...
106 views

### Reaction of orthocresol with butyrolactone in presence of AlCl3 and heat

What will be the major product of the following reaction? Please also help me with the mechanism. I'm not sure whether C- acylation or O- acylation will occur here. And if O- acylation does occur, I ...
55 views

### Why does d/l-2,3-dibromobutane on reaction with NaI/acetone give cis-2-butene?

This is what I have read/know about the dehalogenation of vicinal dihalides by NaI/acetone: The two halides which are leaving must be on opposite sides (from the mechanism). In case they are present ...
32 views

### How Can I Induce Corrosion Electrochemically?

I'm very interested in measuring corrosion in metal alloys, particularly in salt solutions. I understand metals corrode over time, however, I was wondering if it's possible to electrochemically "speed ...
7 views

### Determining the number of ion of a radical [closed]

In 500 g white vitriol(ZnSO4.7H2O), what will be the exact number of ion of SO4^2- ? Any kind of clue or help will be appreciated. Thank you.
14 views

### what is the difference between oxidation state, charge and valency? [duplicate]

Is there any specific atom or compound or molecule possessing oxidation state different from charge and valency, so that we can clearly understand the difference between the three.
16 views

### Why is a solution of salt used instead of the salt in test for sulphate ion?

I noticed that in some anion tests like carbonates, the salt is used and in some like sulphate ion the salt solution is used. Why is this so? When do you require a solution of the salt instead of the ...
20 views

### What are Technetium's physical stress characteristics?

I've looked at periodic and data tables from several sources, but none give mechanical / engineering property data on Technetium. Why is this?
15 views

### In dS≥dQ/T, material equilibrium means that there is not material changes at all or that a material change can be reversible and at equilibrium?

I am reading Levine's Physical Chemistry, I know how to arrive to that equation, but I have questions. First, $\mathrm{d}S=\mathrm{d}Q/T$ for material equilibrium, but if there is a heat flow I ...
16 views

### Why does heating glucose in the excess of HI produce n-hexane? [duplicate]

Alcohols react with acid halides such as $\ce{HI}$ to create alkyl halides, as such: $$\ce{C2H5OH + HX → C2H5X}$$ However, this doesn't seem to be the case with glucose, as the entire chain is ...
14 views

### How do I make a 0.5 M citrate buffer at pH 4.5?

I need to make a citrate-sodium citrate buffer at 0.5 M concentration and pH 4.5. I calculated the molarities of the citrate and disodium citrate based on the Henderson Hasselbalch equation, using a ...
53 views

### How To Scan “improper dihedrals” in Gaussian 09?

I am trying to parameterize Amber force field for a novel molecule, but I couldn't obtain improper dihedrals. Because if I scan impropers like dihedrals; later or sooner the molecule is overlapping ...
43 views

### Friedel-Craft reaction with amide substituent

In this question, I know that aniline will not undergo FC reaction as it forms a complex with $\ce {AlCl3}$ and precipitates out. The answer given is (c) and I agree with it. However, the benzene ring ...