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saw5 [17]
3 years ago
13

Suppose you prepare a buffer by adding 0.157 mol of NaH2PO4 and 0.966 mol of Na2HPO4 to 1.0 L of water. What is the pH of the so

lution?
Chemistry
1 answer:
Arlecino [84]3 years ago
5 0

Answer:

pH = 7,0

Explanation:

The buffer producing by the mixture of H₂PO₄⁻ and HPO₄²⁻ is:

H₂PO₄⁻ ⇄ HPO₄²⁻ + H⁺; pka: 7,21

Using the Henderson-Hasselbalch formula:

pH = pka + log₁₀ A⁻ / HA

Where: A⁻ is the conjugate base (HPO₄²⁻) and HA is the weak acid (H₂PO₄⁻)

Replacing the formula:

pH = 7,21 + log₁₀ HPO₄²⁻ / H₂PO₄⁻

As the moles of HPO₄²⁻ are 0,0966 and moles of H₂PO₄⁻ are 0,157:

pH = 7,21 + log₁₀  0,0966 / 0,157

pH = 7,0

I hope it helps!

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Olin [163]

Answer:

The answer is 6.25g.

Explanation:

First create your balanced equation. This will give you the stoich ratios needed to answer the question:

2C8H18 + 25O2 → 16CO2 + 18H2O

Remember, we need to work in terms of NUMBERS, but the question gives us MASS. Therefore the next step is to convert the mass of O2 into moles of O2 by dividing by the molar mass:

7.72 g / 16 g/mol = 0.482 mol

Now we can use the stoich ratio from the equation to determine how many moles of H2O are produced:

x mol H2O / 0.482 mol O2 = 18 H2O / 25 O2

x = 0.347 mol H2O

The question wants the mass of water, so convert moles back into mass by multiplying by the molar mass of water:

0.347 mol x 18 g/mol = 6.25g

8 0
4 years ago
Read 2 more answers
About how many centimeters will make an inch?<br> A)5<br> B)2+<br> C) 200<br> D)10
Rasek [7]

Answer: B) 2+

Explanation:

   There are exactly 2.54 centimeters in an inch, the closest option is:

B) 2+

6 0
2 years ago
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If there are 1.55 x 1024 molecules of hydrogen peroxide (H2O2), what is the mass of the<br>sample? ​
bezimeni [28]

Answer:

87.54 g of H₂O₂

Explanation:

From the question given above, the following data were obtained:

Number of molecules = 1.55×10²⁴ molecules

Mass of H₂O₂ =.?

From Avogadro's hypothesis,

6.02×10²³ molecules = 1 mole of H₂O₂

Next, we shall determine the mass of 1 mole of H₂O₂. This can be obtained as follow:

1 mole of H₂O₂ = (2×1) + (2×16)

= 2 + 32

= 34 g

Thus,

6.02×10²³ molecules = 34 g of H₂O₂

Finally, we shall determine mass of H₂O₂ that contains 1.55×10²⁴ molecules. This can be obtained as follow:

6.02×10²³ molecules = 34 g of H₂O₂

Therefore,

1.55×10²⁴ molecules

= (1.55×10²⁴ × 34)/6.02×10²³

1.55×10²⁴ molecules = 87.54 g of H₂O₂

Thus, 87.54 g of H₂O₂ contains 1.55×10²⁴ molecules.

8 0
3 years ago
"M" represents a metallic element, the oxide of which has the formula M2O. The formula of the chloride of M is..................
Rus_ich [418]
The formula of the chloride of M will be MCI2.
8 0
3 years ago
What is the electron geometry of PF3?
deff fn [24]

Answer:

PF3 has a trigonal pyramidal molecular geometry.

Explanation:

PF3 has four regions of electron density / electron clouds around the central P atom. The regions of electrons make a tetrahedral arrangement with a bond angle of 109.5°. Only three regions of electrons are bonding and one is non-bonding, so the overall shape is trigonal pyramidal.

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3 years ago
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