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fredd [130]
3 years ago
12

citric acid has an acid dissociation constant of 8.4 x 10^-4 it would be most effective for preparation of a buffer with a pH of

(A) 2 (B) 3 (C) 4 (D) 5
Chemistry
1 answer:
Sloan [31]3 years ago
5 0

Answer:

(B) 3

Explanation:

Citric acid has an acid dissociation constant (Ka) of 8.4 × 10⁻⁴. When it forms a buffer with its conjugate base (citrate), we can calculate the pH using the Henderson-Hasselbalch's equation.

pH=pKa+log\frac{[base]}{[acid]}

The optimum range of pH is pKa ± 1. The pKa is -log Ka = -log (8.4 × 10⁻⁴) = 3.1. The buffer would be more effective for pH between 2.1 and 4.1, especially around 3.1. So the best choice is (B) 3.

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A scientist collects 0.24 mole of hydrogen gas in a balloon. The temperature of the hydrogen is 35 degrees Celsius, and the pres
slava [35]

Answer:

             5.77 L

Solution:

Data Given:

                Moles  =  n  =  0.24 mol

                Temperature  =  T  =  35 °C + 273  =  308 K

                 Pressure  =  P  =  1.05 atm

                 Volume  =  V  =  ?

Formula Used:

Let's assume that the hydrogen gas in balloon is acting as an Ideal gas, the according to Ideal Gas Equation,

                 P V  =  n R T

where;  R  =  Universal Gas Constant  =  0.082057 atm.L.mol⁻¹.K⁻¹

Solving Equation for V,

                 V  =  n R T / P

Putting Values,

                 V  =  (0.24 mol × 0.082057 atm.L.mol⁻¹.K⁻¹ × 308 K) ÷ 1.05 atm

                 V  = 5.77 L

6 0
4 years ago
Each molecule of lycopene contains 40 atoms of carbon (plus other atoms). The mass percent of carbon in lycopene is 84.49%. What
IrinaK [193]

Answer: 568g/mol

Explanation:

It should be noted that there are 40 atoms of carbon in lycopene.

Since mass of 1 carbon = 12g/mol

Mass of 40 carbon atoms = 40 × 12g/mol = 480g/mol

Let the molar mass of lycopene be represented by x.

Therefore the molar mass of carbon = x × mass percent of carbon in lycopene

x × 84.49% = 480g/mol

x × 0.8449 = 480g/mol

x = 480/0.8449

x = 568g/mol

The molar mass of lycopene is 568g/mol

5 0
3 years ago
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Lorico [155]

Answer:

F

Cl

Br

I

Explanation:

Br=11.81...

Cl=12.96...

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Iodine=10.45

7 0
3 years ago
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Black_prince [1.1K]

The electron is the only subatomic particle that has a negative charge

8 0
3 years ago
You are walking on a beach and see a split. Explain how a split could have formed from a rocky headland.
kirza4 [7]

Hello, Lindaparker, a spit  could form from a rocky headland where prevailing winds would blow at an angle to the rocky headland, gradually depositing sand and shingle at that place. A spit is a permanent land form resulting from marine deposition and wind deposition. It is usually a long and narrow accumulation of sand or shingle with one joined to the land and the other end projecting at   a narrow angle out into the sea. Salt marshes sometimes form on the sheltered side of a spit.

8 0
3 years ago
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