Question

In: Chemistry

What volume (to the nearest 0.1 mL) of 6.00-M NaOH must be added to 0.400 L...

What volume (to the nearest 0.1 mL) of 6.00-M NaOH must be added to 0.400 L of 0.250-M HNO₂ to prepare a pH = 4.30 buffer?

What volume (to the nearest 0.1 mL) of 5.50-M HCl must be added to 0.250 L of 0.200-M K₂HPO₄ to prepare a pH = 7.10 buffer?

Expert Solution

The reaction between NaOH and HNO₂ can be written as

Moles of HNO2 is 0.4 x 0.25 = 0.1

NaOH + HNO₂ NaNO2 + H₂O ICE table
initial: (6.00 x x1mL) (0.1) 0 0 (mol)
delta: (-6.00x1) (-6.00x1) (6.00x1) (6.00x1) (mol)
eq: (0.0) (0.1 - 6.00x1) (6.00x1) (6.00x1) (mol)

We know the equation:

pH = pKa + log(base/acid)
the pKa of HNO₂ is 3.40

so we get:

4.30 = 3.40 + log([NaNO₂]/[HNO₂])
4.30 = 3.40 + log((6.00x1)/(0.1 - 6x1))

log((6.00x1)/(0.1 - 6x1)) =0.9

(6.00x1)/(0.1 - 6x1) = 7.94

6x1 = 0.794 - 47.66x1

53.66x1 = 0.794

x1 = 0.794/53.66

x1 = 0.01479 L

14.8 mL of 6.0 M NaOH is required

The reaction between HCl and K₂HPO₄ is

moles of K₂HPO₄ is 0.25 x 0.2 = 0.05

HCl + K₂HPO₄ KCl + KH₂PO4 ICE table

initial 5.5x1 0.05 0 0

change -5.5x1 -5.5x1 5.5x1 5.5x1

equilibrium 0 0.05-5.5x1 5.5x1 5.5x1

We know the equation:

pH = pKa + log(base/acid)
the pKa of K₂HPO₄ is 7.21

so we get:

7.1 = 7.21 + log([K₂HPO₄]/[KH₂PO₄])
7.1 = 7.21 + log([0.05-5.5x1]/[5.5x1])

log([0.05-5.5x1]/[5.5x1]) = -0.11

[0.05-5.5x1]/[5.5x1] = 0.776

0.05-5.5x1 = 4.27x1

0.05 = 9.77x1

x1= 0.05/9.77

x1 = 0.00511L

5.10 mL of 5.50-M HCl

queen_honey_blossom answered 2 years ago

What volume (to the nearest 0.1 mL) of 5.30-M NaOH must be added to 0.700 L...

What volume (to the nearest 0.1 mL) of 5.30-M NaOH must be added to 0.700 L of 0.350-M HNO2 to prepare a pH = 3.70 buffer? What volume (to the nearest 0.1 mL) of 4.80-M HCl must be added to 0.550 L of 0.250-M K2HPO4 to prepare a pH = 8.00 buffer?

What volume (to the nearest 0.1 mL) of 5.20-M NaOH must be added to 0.500 L...

What volume (to the nearest 0.1 mL) of 5.20-M NaOH must be added to 0.500 L of 0.350-M HNO2 to prepare a pH = 3.50 buffer?

a.) What volume (to the nearest 0.1 mL) of 4.50-M NaOH must be added to 0.300...

a.) What volume (to the nearest 0.1 mL) of 4.50-M NaOH must be added to 0.300 L of 0.150-M HNO2 to prepare a pH = 3.20 buffer? ______ mL b.) What volume (to the nearest 0.1 mL) of 4.00-M HCl must be added to 0.700 L of 0.350-M K2HPO4 to prepare a pH = 7.50 buffer? _______ mL

What volume (to the nearest 0.1 mL) of 7.10-M HCl must be added to 0.550 L...

What volume (to the nearest 0.1 mL) of 7.10-M HCl must be added to 0.550 L of 0.350-M K2HPO4 to prepare a pH = 7.50 buffer?

1a)What volume (to the nearest 0.1 mL) of 7.10-M HCl must be added to 0.550 L...

1a)What volume (to the nearest 0.1 mL) of 7.10-M HCl must be added to 0.550 L of 0.350-M K2HPO4 to prepare a pH = 7.50 buffer? b)What volume (to the nearest 0.1 mL) of 7.60-M NaOH must be added to 0.700 L of 0.200-M HNO2 to prepare a pH = 3.20 buffer? c)How many mL (to the nearest mL) of 0.250-M KF solution should be added to 740. mL of 0.220-M HF to prepare a pH = 3.10 solution? b)What...

a) What volume (to the nearest 0.1 mL) of 6.60-M HCl must be added to 0.450...

a) What volume (to the nearest 0.1 mL) of 6.60-M HCl must be added to 0.450 L of 0.200-M K2HPO4 to prepare a pH = 7.40 buffer? b) What volume (to the nearest 0.1 mL) of 7.10-M NaOH must be added to 0.600 L of 0.250-M HNO2 to prepare a pH = 3.10 buffer?

how much 6.00 m naoh must be added to 610.0 ml of a buffer that is...

how much 6.00 m naoh must be added to 610.0 ml of a buffer that is 0.0185 m acetic acid ad 0.0235 m sodium acetate to raise the ph to 5.75?

What volume of a 0.1 M NaOH solution must be combined with 25 mL of 0.2...

What volume of a 0.1 M NaOH solution must be combined with 25 mL of 0.2 M HNO3 to reach a pH of 11.5?

Calculate the volume (in mL) of 0.170 M NaOH that must be added to 259 mL...

Calculate the volume (in mL) of 0.170 M NaOH that must be added to 259 mL of 0.0419 M 3-(N-Morpholino)propanesulfonic acid (MOPS) to give the solution a pH of 7.55. The pKa of MOPS = 7.18.

a) Calculate the volume (in ML) of 0.170 M NaOH that must be added to 365...

a) Calculate the volume (in ML) of 0.170 M NaOH that must be added to 365 mL of 0.0515 M 3-(N-Morpholino) propanesulfonic acid (MOPS) to give the solution a pH of 7.55. The pKa of MOPS =7.18. b) A buffer with a pH of 4.24 contains 0.11 M of sodium benzoate and 0.10 M of benzoic acid. What is the concentration of [H+] in the solution after the addition of 0.056 mol of HCl to a final volume of 1.6...