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PtichkaEL [24]
3 years ago
8

If a buffer contains 1.05M B and 0.750M BH+ has the pH of 9.5. What would be the pH after 0.005mol of HCL is added to 0.5L of so

lution
Chemistry
1 answer:
Leviafan [203]3 years ago
3 0

Answer:

Final pH: 9.49.

Round to two decimal places as in the question: 9.5.

Explanation:

The conjugate of B is a cation that contains one more proton than B. The conjugate of B is an acid. As a result, B is a weak base.

What's the pKb of base B?

Consider the Henderson-Hasselbalch equation for buffers of a weak base and its conjugate acid ion.

\displaystyle \text{pOH} = \text{pK}_b + \log{\frac{[\text{Salt}]}{[\text{Base}]}}.

\text{pOH} = \text{pK}_w - \text{pH}.

\text{pK}_w = 14.

\text{pOH} = 14 - 9.5 = 4.5

\displaystyle \text{pK}_b = \text{pOH} -\log{\frac{[\text{Salt}]}{[\text{Base}]}}\\\phantom{\text{pK}_b} = 4.5 - \log{\frac{0.750}{1.05}} \\\phantom{\text{pK}_b} =4.64613.

What's the new salt-to-base ratio?

The 0.005 mol of HCl will convert 0.005 mol of base B to its conjugate acid ion BH⁺.

Initial:

  • n(\text{B}) = c\cdot V = 1.05 \times 0.5 = 0.525\;\text{mol};
  • n(\text{BH}^{+}) = c\cdot V = 0.750 \times 0.5 = 0.375\;\text{mol}.

After adding the HCl:

  • n(\text{B}) = 0.525 - 0.005 = 0.520\;\text{mol};
  • n(\text{BH}^{+}) = 0.375+ 0.005 = 0.380\;\text{mol}.

Assume that the volume is still 0.5 L:

  • \displaystyle [\text{B}] = \frac{n}{V} = \frac{0.520}{0.5} = 1.04\;\text{mol}\cdot\text{dm}^{-3}.
  • \displaystyle [\text{BH}^{+}] = \frac{n}{V} = \frac{0.380}{0.5} = 0.760\;\text{mol}\cdot\text{dm}^{-3}.

What's will be the pH of the solution?

Apply the Henderson-Hasselbalch equation again:

\displaystyle \text{pOH} = \text{pK}_b + \log{\frac{[\text{Salt}]}{[\text{Base}]}} = 4.64613 + \log{\frac{0.760}{1.04}} = 4.50991

\text{pH} = \text{pK}_w - \text{pOH}= 14 - 4.50991 = 9.49.

The final pH is slightly smaller than the initial pH. That's expected due to the hydrochloric acid. However, the change is small due to the nature of buffer solutions: adding a small amount of acid or base won't significantly impact the pH of the solution.

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How many grams of 02 will be formed from 6.5 moles of KCLO3
Allisa [31]

Answer:

312 g of O₂

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

2KClO₃ —> 2KCl + 3O₂

From the balanced equation above,

2 mole of KClO₃ decomposed to 3 moles of O₂.

Next, we shall determine the number of mole of O₂ produced by the reaction of 6.5 moles of KClO₃. This can be obtained as follow:

From the balanced equation above,

2 mole of KClO₃ decomposed to 3 moles of O₂.

Therefore, 6.5 moles of KClO₃ will decompose to produce = (6.5 × 3)/2 = 9.75 moles of O₂.

Finally, we shall determine the mass of 9.75 moles of O₂. This can be obtained as follow:

Mole of O₂ = 9.75 moles

Molar mass of O₂ = 2 × 16 = 32 g/mol

Mass of O₂ =?

Mole = mass / Molar mass

9.75 = Mass of O₂ / 32

Cross multiply

Mass of O₂ = 9.75 × 32

Mass of O₂ = 312 g

Thus, 312 g of O₂ were obtained from the reaction.

4 0
2 years ago
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Which of the following represents an endothermic reaction?
Softa [21]

Answer:

<h2><em><u>A</u></em><em><u>N</u></em><em><u>S</u></em><em><u>W</u></em><em><u>E</u></em><em><u>R</u></em></h2>

The second one would be one of the application of an endothermic reaction as because endothermic reaction always have the heat in the process to mix the reactants and form the products as here in a burning wood when the wood is supplied with heat then it change into products as ashes and smoke fumes So here due to the heat is involved to form the products thats the reaction is endothermic reaction.

Hope it helps

8 0
2 years ago
Calculate the moles of 12.354 grams of c6h12o6
gavmur [86]

The correct answer is 0.06857 moles.

C₆H₁₂O₆, that is, glucose has six carbons, twelve hydrogens, and six oxygen atoms. The atomic weight of C, H and O are as follows:

Six atoms of carbon = 6 × 12.01 g = 72.06 g

Twelve atoms of hydrogen = 12 × 1.008 g = 12.096 g

Six atoms of oxygen = 6 × 16.00 g = 96.00 g

So, the molar mass of C₆H₁₂O₆ is 72.06 g + 12.096 g + 96.0 g = 180.156 g.

It can also be written in the form as 180.16 g of C₆H₁₂O₆ is equal to 1 mole of C₆H₁₂O₆or 180.16 g/mole (as the molar mass)

Now, there is a need to find moles of 12.354 grams of C₆H₁₂O₆. So, the final conversion is:

12.354 g C₆H₁₂O₆ × 1 mole of C₆H₁₂O₆ / 180.16 g C₆H₁₂O₆

= 0.06857 moles

5 0
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Can someone help me write the complete balanced equation for the decomposition of magnesium chlorate (Mg(ClO3)2).
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The expectancy of how long a product will last divided by two!
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