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pav-90 [236]
3 years ago
5

1. Calculate the concentration of hydronium ion of both buffer solutions at their starting pHs. Calculate the moles of hydronium

ion present in 20.0 mL of each buffer. 2. A change of pH by 1 unit means a change in hydronium ion concentration by a factor of 10. Calculate the number of moles of NaOH that would theoretically be needed to decrease the moles of hydronium you calculated in
Chemistry
1 answer:
lilavasa [31]3 years ago
5 0

Answer:

This question is incomplete, here's the complete question:

1. Calculate the concentration of hydronium ion of both buffer solutions at their starting pHs. Calculate the moles of hydronium ion present in 20.0 mL of each buffer.

Buffer A

Mass of sodium acetate used: 0.3730 g

Actual ph of the buffer 5.27

volume of the buffer used in buffer capacity titration 20.0 mL

Concentration of standardized NaOH 0.100M

moles of Naoh needed to change the ph by 1 unit for the buffer 0.00095mol

the buffer capacity 0.0475 M

Buffer B

Mass of sodium acetate used 1.12 g

Actual pH of the buffer 5.34

Volume of the buffer used in buffer capacity titration 20.0 mL

Concentration if standardized NaOH 0.100 M

moles of Naoh needed to change the ph by 1 unit 0.0019 mol

the buffer capacity 0.095 M

2.) A change of pH by 1 unit means a change in hydronium ion concentration by a factor of 10. Calculate the number of moles of NaOH that would theoretically be needed to decrease the moles of hydronium you calculated in #1 by a factor of 10 for each buffer. Are there any differences between your experimental results and the theoretical calculation?

3.) which buffer had a higher buffer capacity? Why?

Explanation:

Formula,

moles = grams/molar mass

molarity = moles/L of solution

1. Buffer A

molarity of NaC2H3O2 = 0.3731 g/82.03 g/mol x 0.02 L = 0.23 M

molarity of HC2H3O2 = 0. 1 M

Initial pH

pH = pKa + log(base/acid)

= 4.74 + log(0.23/0.1)

= 5.10

pH = -log[H3O+]

[H3O+] = 7.91 x 10^-6 M

In 20 ml buffer,

moles of H3O+ = 7.91 x 10^-6 M x 0.02 L

= 1.58 x 10^-7 mol

Buffer B

molarity of NaC2H3O2 = 1.12 g/82.03 g/mol x 0.02 L = 0.68 M

molarity of HC2H3O2 = 0.3 M

Initial pH

pH = pKa + log(base/acid)

= 4.74 + log(0.68/0.3)

= 5.10

pH = -log[H3O+]

[H3O+] = 7.91 x 10^-6 M

In 20 ml buffer,

moles of H3O+ = 7.91 x 10^-6 M x 0.02 L

= 1.58 x 10^-7 mol

2. let x moles of NaOH is added,

Buffer A,

pH = 5.10

[H3O+] = 7.91 x 10^-6 M

new pH = 4.10

new [H3O+] = 7.91 x 10^-5 M

moles of NaOH to be added = (7.91 x 10^-5 - 7.91 x 10^-6) x 0.02 L

= 1.42 x 10^-6 mol

3. Buffer B with greater concentration of NaC2H3O2 and HC2H3O2 has higher buffer capacity as it resists pH change to a wider range due to addition of acid or base to the system as compared to low concentration of Buffer A

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Explanation:

A phase diagram is a diagram that shows the effects of temperature and pressure on phase.

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4 0
2 years ago
What would be the total volume of the new solution when it is changed from 0.2 M to 0.04 M?
34kurt
The question is incomplete.

You need two additional data:

1) the original volume
2) what solution you added to change the volume.

This is a molarity problem, so remember molarity definition and formula:

M = n / V in liters: number of moles per liter of solution

To give you the key to answer this kind of questions, supppose the original volumen was 1 ml and that you added only water (solvent).

The original solution was:

V= 1 ml
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Using the formula for molarity, M = n / V

n = M×V = 0.2 M × (1 / 10000)l = 0.0002 moles

For the final solution:

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From M = n / V ⇒ V = n / M = 0.002 moles / 0.04 M = 0.05 l

Change to ml ⇒ 0.05 l × 1000 ml / l = 50 ml.  This would be the answer for the hypothetical problem that I assumed for you.

I hope this gives you all the cues you need to answer similar problems about molarity.
6 0
3 years ago
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What is the ratio of hydrogen atoms to sulfur atoms in sulfuric acid, h2so4?
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1) Given the balance equation below. Calculate how much Na3PO4 in grams you
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Answer:

<u>136.67 g of Na3PO4 i</u>s required to create 100 gram of NaOH.

Explanation:

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1 mole Na3PO4 = 164 g/mole (Molar mass)

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Now,

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164 g/mol of Na3PO4 produce = 3(40) g/mol of NaOH

or

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