Question

How many grams of solid NaOH (Mol. Wt. = 40 g mol-1) must be
added to a 0.15 L solution of 0.02 mol L–1 glycine hydrochloride to
adjust the pH to 2.65? (p*K*a1 = 2.35, p*K*a2 =
9.78)

(A) 79.92 g

(B) 7.992 g

(C) 0.799 g

(D) 0.079 g

(E) 0.008 g

Answer #1

Answer is **(D) 0.079g**

Formula used to solve this problem is,

pH = pKa + log([A-]/[HA])

Reaction is,

H_{2}N-CH_{2}-COOH
= H_{2}N-CH_{2}-COO^{-} +
H_{3}N-CH_{2}-COO^{+}

^{HA }A^{-} (charged) neutral

before reaction 0.02 0 0

after reaction 0.02-x x x

Now,

pH = pKa + log([A-]/[HA])

2.65 = 2.35 + log (x / (0.02-x))

0.3 = log (x / (0.02-x))

(x / (0.02-x)) = 1.995

x = 0.0133 mole L^{-1}

Amount of NaOH in 0.0133 mole = 40 * 0.0133 = 0.5324 g

Amount of NaOH in 0.15 L solution = 0.5324 * 0.15 = 0.0798 g ~
**0.079 g**

**Thus, 0.079 g of NaOH is required to adjust the pH at
2.65.**

How many grams of dipotassium succinate trihydrate
(K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 730.0 mL of a
0.0574 M succinic acid solution to produce a pH of 5.865? Succinic
acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2).

How many grams of dipotassium succinate trihydrate
(K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 610.0 mL of a
0.0460 M succinic acid solution to produce a pH of 5.956? Succinic
acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2).

How many grams of dipotassium succinate trihydrate
(K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 710.0 mL of a
0.0485 M succinic acid solution to produce a pH of 5.844? Succinic
acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2).

How many grams of dipotassium succinate trihydrate
(K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 800.0 mL of a
0.0568 M succinic acid solution to produce a pH of 5.968? Succinic
acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2).

How many grams of dipotassium succinate trihydrate
(K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 540.0 mL of a
0.0329 M succinic acid solution to produce a pH of 5.966? Succinic
acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2).

How many grams of dipotassium succinate trihydrate
(K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 710.0 mL of a
0.0304 M succinic acid solution to produce a pH of 5.989? Succinic
acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2). (Note:
324.45g is not correct)

Question 1 a) Find the pH of a solution prepared by dissolving
1.00 g of glycine amide hydrochloride (BH+); [Mwt = 110.54] plus
1.00 g of glycine amide (B); [Mwt = 74.08] in 0.10 L. pKa =
8.04
b) How many grams of glycine amide should be added to 1.00 g of
glycine amide hydrochloride (BH+) to give 100 mL of solution with
pH 8.00?
c) What would be the pH if the solution in part (a) were mixed with...

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...

1
a. How many grams (to the nearest 0.01 g) of NH4Cl (Mm = 53.49
g/mol) must be added to 900. mL of 0.923-M solution of NH3 in order
to prepare a pH = 8.90 buffer?
b. What volume (to the nearest 0.1 mL) of 6.70-M NaOH must be
added to 0.550 L of 0.250-M HNO2 to prepare a pH = 3.00
buffer
c. What volume (to the nearest 0.1 mL) of 6.20-M HCl must be
added to 0.400 L...

1. How many grams (to the nearest 0.01 g) of NH4Cl
(Mm = 53.49 g/mol) must be added to 650. mL of 0.951-M
solution of NH3 in order to prepare a pH = 10.50
buffer?
2. What volume (to the nearest 0.1 mL) of 4.40-M HCl must be
added to 0.450 L of 0.150-M K2HPO4 to prepare
a pH = 6.60 buffer?

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