Question

How many grams of Ca(NO2)2 must be added to 4.0 L solution of 0.1 M HNO2 to get a pH of 3.64?

Answer #1

**Solution:**

The balanced chemical rection is,

**2 HNO _{2} + Ca(OH)_{2} =
Ca(NO_{2})_{2} + 2 H_{2}O**

Molar mass of Ca(OH)_{2} = 74.093 g/mol

Molar mass of Ca(NO_{2})_{2} = 132.089 g/mol

Molar mass of HNO_{2} = 47.013 g/mol

molar mass of water = 18 g/mol

[HNO2] = 0.1
M
pH = 3.64 --> [H^{+}] = 10^{-3.64} = 0.000229
M

Molarity = Moles / Volume in Litre

0.000229 = (Ca(NO_{2})_{2} in grams / 132.089) /
4.0 L

Ca(NO_{2})_{2} in grams = 0.12 grams

How many grams of K2HPO4 must be added to 2L of a 0.1 M KH2PO4
SOLUTION TO PRODUCE A PH=7.0 BUFFER? AND CAN YOU IDENTIFY THE ACID,
BASE, CONJUGATE BASE AND CONJUGATE ACID AS WELL. PLEASE WORK THE
STEP OUT STEP BY STEP

How many grams of potassium nitrite need to be added to 250.0mL
of a 0.1234 M HNO2 solution to produce a final buffer at pH= 3.65?
Ka HNO2= 4.5 x 10 ^-4

What volume (to the nearest 0.1 mL) of 4.00-M NaOH must be added
to 0.650 L of 0.350-M HNO2 to prepare a pH = 3.30 buffer?

What volume (to the nearest 0.1 mL) of 5.30-M NaOH must be added
to 0.350 L of 0.350-M HNO2 to prepare a pH = 3.20
buffer?

What volume (to the nearest 0.1 mL) of 6.80-M NaOH must be added
to 0.250 L of 0.300-M HNO2 to prepare a pH = 3.40
buffer?

What volume (to the nearest 0.1 mL) of 7.40-M NaOH must be added
to 0.400 L of 0.350-M HNO2 to prepare a pH = 3.80 buffer?

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...

What volume (to the nearest 0.1 mL) of 5.20-M NaOH must be added
to 0.750 L of 0.300-M HNO2 to prepare a pH = 4.20 buffer?
ml

Calculate the pH of a solution which is 0.400 M in HNO2 and
1.875 M in Ca(NO2)2. The Ka for HNO2 is 4.5 x 10-4

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 8.48Ã—10-2M hydrofluoric
acid solution to prepare a buffer with a pH
of3.807 ?
grams potassium fluoride =
________ g.
PART C
How many grams of...

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