## Search found 149 matches

Wed Mar 24, 2021 11:54 pm
Forum: Chemistry forum
Topic: Copper(II) sulfide react with Nitric acid
Replies: 1
Views: 112

### Copper(II) sulfide react with Nitric acid

Given the reaction between copper (II) sulfide and nitric acid, how many grams of nitric acid will react with 2.00 g of copper(II) sulfide?
3 CuS(s) + 8 HNO3(aq) → 3 Cu(NO3)2(aq) + 2 NO(g) + 4 H2O(l) + 3 S(s)

Answer provided is 2.79 g of HNO3.

My answer is 3.52 g of HNO3

Which is correct?
Wed Mar 24, 2021 11:43 pm
Forum: Chemistry forum
Topic: stoichiometry
Replies: 4
Views: 202

### Re: stoichiometry

The mass of carbon dioxide (CO2) formed if 38.9 g of acetylene(C2H2) reacted completely with oxygen(O2) is 65.74g.
Wed Mar 24, 2021 9:02 am
Forum: Chemistry forum
Topic: Stoichiometry question
Replies: 1
Views: 149

### Stoichiometry question

For the given balanced reaction: Ca3(PO4)2 + 3 SiO2 + 5 C → 3 CaSiO3 + 5 CO + 2 P 1) How many moles of silicon dioxide are required to react with 0.35 mol of carbon? 2) How many moles of calcium phosphate are required to produce 0.45 mol of calcium silicate? How to answer both these questions? Answe...
Tue Mar 23, 2021 4:23 am
Forum: Chemistry forum
Topic: Example of pKa and pH problem.
Replies: 7
Views: 208

### Re: Example of pKa and pH problem.

Whatever is given on https://www.thoughtco.com/the-ph-and-pka-relationship-603643#:~:text=The%20lower%20the%20pH%2C%20the,than%20a%20diluted%20strong%20acid. , I reproduced here. Consider the reaction HNO2 + NaOH → NaNO2 + H2O , Now we have 1.0 M of HNO2 and 0.225 M of NO2⁻. So, pH= 3.13 + log (0.22...
Mon Mar 22, 2021 8:54 am
Forum: Chemistry forum
Topic: Example of pKa and pH problem.
Replies: 7
Views: 208

### Re: Example of pKa and pH problem.

I don't understand how does Log(NO2⁻ / HNO2) = Log(1/0.225 )? Henderson- Hasselbalch equation states pH= pKa + log([conjugate Base ]/[ weak acid]) In this case, NO2⁻ ia a conjugate base and its concentration is unknown. How to find out that? The concentration of HNO2 is 1.0 M. But in ths solution it...
Mon Mar 22, 2021 6:28 am
Forum: Chemistry forum
Topic: Example of pKa and pH problem.
Replies: 7
Views: 208

### Re: Example of pKa and pH problem.

In the question, the concentration of NaNO2 is 0.225 M and that of HNO2 is 1.0 M.

But in the handerson-Hasselbalch equation, concentration of HNO2 is 0.225 and of NO2⁻ , it is 1.0 M. How is that?

I think the reaction is NaNO2 + HNO2 → NaOH + NO + NO2
Mon Mar 22, 2021 6:19 am
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Re: Ortho-fluoro aniline and pH reactions

If pKa is 3.204, then ka= 0.000625, this means 0.000625* 0.01= x * x , → x= 0.0025 Now is this hydroxide ion concentration? If it is so, then poH=-log(0.0025)=2.602, this means pH= 14.000 -2.602=11.398 Is this computation correct?
Mon Mar 22, 2021 5:39 am
Forum: Chemistry forum
Topic: Example of pKa and pH problem.
Replies: 7
Views: 208

### Example of pKa and pH problem.

Example pKa and pH Problem Find [H⁺] for a solution of 0.225 M NaNO2 and 1.0 M HNO2. The Ka value (from a table) of HNO2 is 5.6 e-4. (In table, It is 7.4e-4) pKa = −log Ka = −log(7.4e−4) = 3.14 pH = pka + log ([A⁻]/[HA]) pH = pKa + log([NO2-]/[HNO2]) pH = 3.14 + log(1/0.225) pH = 3.14 + 0.648 = 3.78...
Mon Mar 22, 2021 4:55 am
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Re: Ortho-fluoro aniline and pH reactions

Sun Mar 21, 2021 11:24 pm
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Re: Ortho-fluoro aniline and pH reactions

Conjugate acid of o-FC6H4NH2 is o-FC6H4NH3
Reaction equation is FC6H4NH2 + H2O → FC6H4NH3⁺ + OH⁻

So, 1.6E-11=x*x/0.01M → x= 4.0e-7, Hence pOH=-log(4.0e-7)= 6.4. so, pH=14.0-6.4=7.6 Is this computaion correct?
Sun Mar 21, 2021 8:24 am
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Re: Ortho-fluoro aniline and pH reactions

Fluorine atom will accept proton from water in ortho-fluoro aniline.

You said pKa of the o-fluoro aniline is 3.2, so its pH is 3.2 as well.

Now, how to answer part d and e?
Sun Mar 21, 2021 3:41 am
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Re: Ortho-fluoro aniline and pH reactions

Are Yoy talking about mesomeric effect and inductive effect of Fluorine?

Is this correct chemical structure drawing for ortho-fluoro aniline?
Sat Mar 20, 2021 11:22 pm
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Re: Ortho-fluoro aniline and pH reactions

Chemical structure of ortho-fluoro aniline is as follows:

Nitrogen atom can accept proton from water.

o-FC6H4NH2 is stronger base than C6H5NH2 because F can act as base (electron pairs donor)
Sat Mar 20, 2021 3:22 am
Forum: Chemistry forum
Topic: Ortho-fluoro aniline and pH reactions
Replies: 14
Views: 385

### Ortho-fluoro aniline and pH reactions

Consider ortho-fluoro aniline (o-FC6H4NH2). a.Give an electron-dot formula for this compound and indicate with an arrow which atoms can accept a proton. Circle the atom that actually does accept a proton from water. b.Determine whether o-FC6H4NH2 is a stronger or weaker base than aniline itself (C6H...
Sat Mar 20, 2021 3:14 am
Forum: Chemistry forum
Topic: Acid-Base Titrations
Replies: 20
Views: 769

### Re: Acid-Base Titrations

Oh, yes, Thank you.