Question

How many grams of solid sodium fluoride should be added to 0.500 L of a 0.248 M hydrofluoric acid solution to prepare a buffer with a pH of 3.988 ? grams sodium fluoride = g.

Answer #1

Ka = 3.5*10^-4

pKa = - log (Ka)

= - log(3.5*10^-4)

= 3.4559

use formula for buffer

pH = pKa + log ([NaF]/[HF])

3.988 = 3.4559 + log ([NaF]/[HF])

log ([NaF]/[HF]) = 0.5321

[NaF]/[HF] = 3.4046

[NaF] = 0.8443

volume , V = 0.5 L

we have below equation to be used:

number of mol,

n = Molarity * Volume

= 0.8443*0.5

= 0.4222 mol

Molar mass of NaF = 1*MM(Na) + 1*MM(F)

= 1*22.99 + 1*19.0

= 41.99 g/mol

we have below equation to be used:

mass of NaF,

m = number of mol * molar mass

= 0.4222 mol * 41.99 g/mol

= 17.7 g

Answer: 17.7 g

How many grams of solid sodium fluoride should be added to 0.500
L of a 0.241 M hydrofluoric acid solution to prepare a buffer with
a pH of 3.720 ?

PART A
How many grams of solid sodium
cyanide should be added to 0.500
L of a 0.135 M hydrocyanic acid
solution to prepare a buffer with a pH of 8.597
?
grams sodium cyanide = _________
g.
PART B
How many grams of solid potassium
fluoride should be added to 0.500
L of a 8.48×10-2M hydrofluoric
acid solution to prepare a buffer with a pH
of3.807 ?
grams potassium fluoride =
________ g.
PART C
How many grams of...

How many grams of solid ammonium
bromide should be added to 0.500
L of a 0.164 M ammonia solution
to prepare a buffer with a pH of 8.640
?
grams ammonium bromide
= g.

Part A: How many grams of solid ammonium
chloride should be added to 1.50
L of a 5.46×10-2 M
ammonia solution to prepare a buffer with a pH of
8.630?
Part B: How many grams of solid potassium
nitrite should be added to 2.00 L
of a 0.255 M nitrous acid
solution to prepare a buffer with a pH of
2.353?

How many grams of solid potassium cyanide should be added to
1.00 L of a 0.239 M hydrocyanic acid solution to prepare a buffer
with a pH of 10.174 ?
grams potassium cyanide=

How many grams of sodium fluoride (NaF) would need to be added
to 1.00 L of 0.19 M HF to yield a solution with pH = 4.93? (pKa of
HF = 3.17)

1. How many grams of sodium lactate, NaC3H5O3, should be
added to 1.00 L of 0.150 M lactic acid, HC3H5O3, to form a buffer
solution with a pH of 3.90? (Ka = 1.4*10^-4 for lactic acid)
How do you do this?

How many grams of dry NH4Cl need to be added to 2.20 L of a
0.500 M solution of ammonia, NH3, to prepare a buffer
solution that has a pH of 8.62? Kb for ammonia is
1.8×10−5.

How many grams of dry NH4Cl need to be added to 2.50 L of a
0.500 M solution of ammonia, NH3, to prepare a buffer solution that
has a pH of 8.69? Kb for ammonia is 1.8×10−5?

How many grams of sodium acetate
(NaC2H3O2) must be added to 2.0 L
of a 0.500M acetic acid solution to produce a buffer of
pH=5.00?
At what pH would this buffer have the highest capacity?

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