Question

Find the pH for the following solutions:

a) A solution that is 0.115 M in HBr and 0.130 M in HCHO2

b) A 0.25 M CH3NH3I solution? (K_{b} = 4.4 x
10^{-4} M for CH_{3}NH_{2})

c) A 0.0180 M solution of HClO_{2}? (K_{a} = 1.1
x 10^{-2} M)

d) A 0.0180 M solution of Sr(OH)_{2}

e) A 0.170 M solution
of KOCl? (For HOCl, K_{a} = 3.5 x 10^{-8} M)

f) A solution that is 3.00×10−2M in HI and 9.00×10−3M in HF.
(For HF, pK_{a} = 3.14)

g) A solution that is 0.105 M in KF and 0.105 M in KCl? (for HF,
pK_{a} = 3.14)

I'm having a hard time in chem class, please help understand how to know if it's an acid or base, and what the steps are to find pH. Thanks!

Answer #1

solution:

a)

b)

0.25 M CH3NH3I

it is a salt oe weakamine,strongacid.So that it is acidic.

pH = 7-1/2(pkb+logC)

pkb of CH3CH2NH2 = 3.19

= 7 - 1/2 (3.19+Log(0.25))

= 5.7

c)

HClO2 + H2O ---> H3O+ + ClO2-

ka = [H3O+] [ClO2-] /[HClO2]

1.1*10^{-2}= [x][x]/[0.15]

1.1*10^{-2}*0.15= x^{2}

0.00165 = x^{2}

taking square rrot of boht the sides we get x= 0.0406 M

x = [H3O+] = [H+]

so, p^{H} = - log[H+]

p^{H} = - log[0.0406] = 1.34

d)

Sr(OH)_{2}--------> Sr^{2+} + 2OH-

so, [OH^{-}] =2*0.018

[OH^{-}] = 0.036 M

so pOH = -log[OH] = - log[0.036]

pOH = 1.44

so, Ph = 14 - pOH = 14 - 1.44

pH = 12.6

=13.7

Find the pH of each of the following solutions
of mixtures of acids.
Part A
0.130 M in HBr and 0.115 M in HCHO2
Part B
0.170 M in HNO2 and 8.0×10−2 M in HNO3
Part C
0.190 M in HCHO2 and 0.23 M in HC2H3O2
Part D
4.0×10−2 M in acetic acid and 4.0×10−2 M
in hydrocyanic acid

Find the pH of each of the following
solutions
A. 0.125M in HBr and 0.135M in HCHO2
B. 0.155M in HNO2 and 9.0�10-2M in HNO3
C. 0.180M in HCHO2 and 0.23M in HC2H3O2
D. 6.0�10-2M in acetic acid and 6.0�10-2M
in hydrocyanic acid
E. 7.00�10-2M HNO3
F. 0.160M HNO2
G. 2.10�10-2M KOH
H. 0.250M CH3NH3I
I. 0.320M KC6H5O

A.) Find the pH of a 0.338 M NaF solution. (The Ka of
hydrofluoric acid, HF, is 3.5×10?4.)
B.) Determine the [OH?] of a 0.30 M solution of NaHCO3. and
Determine the pH of this solution.
C.)Find the [OH?] of a 0.46 M methylamine
(CH3NH2) solution. (The value of Kb for methylamine
(CH3NH2) is 4.4×10?4.) include units
D.) Find the pH of a 0.46? M methylamine
(CH3NH2) solution.

1. What is the pH of a solution prepared by mixing 50 ml of a
0.10M solution of HF with 25 ml of a 0.20M solution of NaF? (The
pKa of HF is 3.14)
2. What is the pH of a solution that is 0.2M in acetic acid (Ka
= 1.8 x 10-5) and 0.2M in sodium acetate?
Thank you guys!

a. What is the pH of a solution containing 0.2 M HA and 0.1 M
A- ? Ka of HA is 0.002.
b.
What ratio of NaCHO2:HCHO2 would be required to
make a buffer with pH 2.97 ?
Formic Acid, HCHO2 pKa = 3.74

Find the pH of each of the following solutions of mixtures of
acids.
8.0×10−2 M in HNO3 and 0.170 M in
HC7H5O2
1.5×10−2 M in HBr and 2.0×10−2 M in
HClO4
9.5×10−2 M in HF and 0.230 M in
HC6H5O
0.100 M in formic acid and 4.5×10−2 M in hypochlorous
acid

Find the pH of a 0.265 M HClO2(aq) solution. For HClO2,
Ka=0.011.

33. Calculate the pH of a solution that is 1.00 M HF,
2.00 M HCl, and 1.439 MNaF.
(Ka = 7.2 10–4)
3.14
3.30
2.48
2.98
0.25
34. If the solid CuF2 has a solubility of 0.0020 mol/L, what is
the value of Ksp?
1.8 x 10-7
4.0 x 10-6
3.2 x 10-8
8.0 x 10-9
none of the above

Find the pH of a 0.300 M HF (Ka=6.3×10−4) solution.
Find the percent dissociation of a 0.300 M HF solution

A 25.0 mL sample of a 0.115 M solution of acetic acid is
titrated with a 0.144 M solution of NaOH. Calculate the pH of the
titration mixture after 10.0, 20.0, and 30.0 mL of base have been
added. (The Ka for acetic acid is 1.76 x 10^-5).
10.0 mL of base =
20.0 mL of base =
30.0 mL of base =

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