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What is [OH ] in a solution of 0.125 M CH 3 NH 2 and 0.130 M CH 3 NH 3 Cl?
CH 3 NH 2 ( a q ) + H 2 O ( l ) CH 3 NH 3 + ( a q ) + OH ( a q ) K b = 4.4 × 10 −4

[OH ] = 4.2 × 10 −4 M

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What is [OH ] in a solution of 1.25 M NH 3 and 0.78 M NH 4 NO 3 ?
NH 3 ( a q ) + H 2 O ( l ) NH 4 + ( a q ) + OH ( a q ) K b = 1.8 × 10 −5

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What concentration of NH 4 NO 3 is required to make [OH ] = 1.0 × 10 −5 in a 0.200- M solution of NH 3 ?

[NH 4 NO 3 ] = 0.36 M

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What concentration of NaF is required to make [H 3 O + ] = 2.3 × 10 −4 in a 0.300- M solution of HF?

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What is the effect on the concentration of acetic acid, hydronium ion, and acetate ion when the following are added to an acidic buffer solution of equal concentrations of acetic acid and sodium acetate:

(a) HCl

(b) KCH 3 CO 2

(c) NaCl

(d) KOH

(e) CH 3 CO 2 H

(a) The added HCl will increase the concentration of H 3 O + slightly, which will react with CH 3 CO 2 and produce CH 3 CO 2 H in the process. Thus, [ CH 3 CO 2 ] decreases and [CH 3 CO 2 H] increases.
(b) The added KCH 3 CO 2 will increase the concentration of [ CH 3 CO 2 ] which will react with H 3 O + and produce CH 3 CO 2 H in the process. Thus, [H 3 O + ] decreases slightly and [CH 3 CO 2 H] increases.
(c) The added NaCl will have no effect on the concentration of the ions.
(d) The added KOH will produce OH ions, which will react with the H 3 O + , thus reducing [H 3 O + ]. Some additional CH 3 CO 2 H will dissociate, producing [ CH 3 CO 2 ] ions in the process. Thus, [CH 3 CO 2 H] decreases slightly and [ CH 3 CO 2 ] increases.
(e) The added CH 3 CO 2 H will increase its concentration, causing more of it to dissociate and producing more [ CH 3 CO 2 ] and H 3 O + in the process. Thus, [H 3 O + ] increases slightly and [ CH 3 CO 2 ] increases.

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What is the effect on the concentration of ammonia, hydroxide ion, and ammonium ion when the following are added to a basic buffer solution of equal concentrations of ammonia and ammonium nitrate:

(a) KI

(b) NH 3

(c) HI

(d) NaOH

(e) NH 4 Cl

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What will be the pH of a buffer solution prepared from 0.20 mol NH 3 , 0.40 mol NH 4 NO 3 , and just enough water to give 1.00 L of solution?

pH = 8.95

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Calculate the pH of a buffer solution prepared from 0.155 mol of phosphoric acid, 0.250 mole of KH 2 PO 4 , and enough water to make 0.500 L of solution.

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How much solid NaCH 3 CO 2 •3H 2 O must be added to 0.300 L of a 0.50- M acetic acid solution to give a buffer with a pH of 5.00? (Hint: Assume a negligible change in volume as the solid is added.)

37 g (0.27 mol)

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What mass of NH 4 Cl must be added to 0.750 L of a 0.100- M solution of NH 3 to give a buffer solution with a pH of 9.26? (Hint: Assume a negligible change in volume as the solid is added.)

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A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate. Use 1.80 × 10 −5 as K a for acetic acid.

(a) What is the pH of the solution?

(b) Is the solution acidic or basic?

(c) What is the pH of a solution that results when 3.00 mL of 0.034 M HCl is added to 0.200 L of the original buffer?

(a) pH = 5.222;
(b) The solution is acidic.
(c) pH = 5.221

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A 5.36–g sample of NH 4 Cl was added to 25.0 mL of 1.00 M NaOH and the resulting solution

diluted to 0.100 L.

(a) What is the pH of this buffer solution?

(b) Is the solution acidic or basic?

(c) What is the pH of a solution that results when 3.00 mL of 0.034 M HCl is added to the solution?

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Which acid in [link] is most appropriate for preparation of a buffer solution with a pH of 3.1? Explain your choice.

To prepare the best buffer for a weak acid HA and its salt, the ratio [ H 3 O + ] K a should be as close to 1 as possible for effective buffer action. The [H 3 O + ] concentration in a buffer of pH 3.1 is [H 3 O + ] = 10 −3.1 = 7.94 × 10 −4 M
We can now solve for K a of the best acid as follows:
[ H 3 O + ] K a = 1 K a = [ H 3 O + ] 1 = 7.94 × 10 −4
In [link] , the acid with the closest K a to 7.94 × 10 −4 is HF, with a K a of 7.2 × 10 −4 .

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Which acid in [link] is most appropriate for preparation of a buffer solution with a pH of 3.7? Explain your choice.

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Which base in [link] is most appropriate for preparation of a buffer solution with a pH of 10.65? Explain your choice.

For buffers with pHs>7, you should use a weak base and its salt. The most effective buffer will have a ratio [ OH ] K b that is as close to 1 as possible. The pOH of the buffer is 14.00 − 10.65 = 3.35. Therefore, [OH ] is [OH ] = 10 −pOH = 10 −3.35 = 4.467 × 10 −4 M .
We can now solve for K b of the best base as follows:
[ OH ] K b = 1
K b = [OH ] = 4.47 × 10 −4
In [link] , the base with the closest K b to 4.47 × 10 −4 is CH 3 NH 2 , with a K b = 4.4 × 10 −4 .

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Which base in [link] is most appropriate for preparation of a buffer solution with a pH of 9.20? Explain your choice.

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What is the pH of 1.000 L of a solution of 100.0 g of glutamic acid (C 5 H 9 NO 4 , a diprotic acid; K 1 = 8.5 × 10 −5 , K 2 = 3.39 × 10 −10 ) to which has been added 20.0 g of NaOH during the preparation of monosodium glutamate, the flavoring agent? What is the pH when exactly 1 mol of NaOH per mole of acid has been added?

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Questions & Answers

who was the first nanotechnologist
Lizzy Reply
k
Veysel
technologist's thinker father is Richard Feynman but the literature first user scientist Nario Tagunichi.
Veysel
Norio Taniguchi
puvananathan
Interesting
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I need help
Richard
anyone have book of Abdel Salam Hamdy Makhlouf book in pdf Fundamentals of Nanoparticles: Classifications, Synthesis
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It could change the whole space science.
puvananathan
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sibaram
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sibaram
hydrothermal synthesis
ISHFAQ
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William
currently
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where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
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Google
da
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Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
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Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
STM - Scanning Tunneling Microscope.
puvananathan
From their positions in the periodic table, arrange the atoms in each of the following series in order of increasing electronegativity: As, H, N, P, Sb
Shylee Reply
how do you find theWhat are the wavelengths and energies per photon of two lines
caroline Reply
The eyes of some reptiles are sensitive to 850 nm light. If the minimum energy to trigger the receptor at this wavelength is 3.15 x 10-14 J, what is the minimum number of 850 nm photons that must hit the receptor in order for it to be triggered?
razzyd Reply
A teaspoon of the carbohydrate sucrose contains 16 calories, what is the mass of one teaspoo of sucrose if the average number of calories for carbohydrate is 4.1 calories/g?
ifunanya Reply
4. On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in the boiling points of acetone (56.2 °C) and 1-propanol (97.4 °C), which have similar molar masses
Kyndall Reply
Calculate the bond order for an ion with this configuration: (?2s)2(??2s)2(?2px)2(?2py,?2pz)4(??2py,??2pz)3
Gabe Reply
Which of the following will increase the percent of HF that is converted to the fluoride ion in water? (a) addition of NaOH (b) addition of HCl (c) addition of NaF
Tarun Reply
Practice Key Terms 3

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Source:  OpenStax, Ut austin - principles of chemistry. OpenStax CNX. Mar 31, 2016 Download for free at http://legacy.cnx.org/content/col11830/1.13
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