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frosja888 [35]
2 years ago
8

Buffer consists of undissociated acid (ha) and the ion made by dissociating the acid (a-). How does this system buffer a solutio

n against decreases in ph?]
Chemistry
1 answer:
docker41 [41]2 years ago
3 0

In buffer solution there is an equilibrium between the acid  HA and its conjugate base A⁻: HA(aq) ⇌ H⁺(aq) + A⁻(aq).

When acid (H⁺ ions) is added to the buffer solution, the equilibrium is shifted to the left, because conjugate base (A⁻) reacts with hydrogen cations from added acid, according to Le Chatelier's principle: H⁺(aq) + A⁻(aq) ⇄ HA(aq). So, the conjugate base (A⁻) consumes some hydrogen cations and pH is not decreasing (less H⁺ ions, higher pH of solution).

A buffer can be defined as a substance that prevents the pH of a solution from changing by either releasing or absorbing H⁺ in a solution.

Buffer is a solution that can resist pH change upon the addition of an acidic or basic components and it is able to neutralize small amounts of added acid or base, pH of the solution is relatively stable


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Microwave ovens are able to cook food because they increase the_______ of water molecules in the food.
Whitepunk [10]

potential energy with the heat given to the food

4 0
2 years ago
If Co(NH3)63+ has a λmax at 440 nm, calculate ΔE for the complex. A) 2.72 x 10-4 kJ/mol B) 4.52 x 10-2 kJ/mol C) 2.72 x 10 2 kJ/
riadik2000 [5.3K]

<u>Answer:</u> The energy of the complex is 2.72\times 10^2kJ

<u>Explanation:</u>

To calculate the energy of the complex, we use the equation given by Planck which is:

\Delta E=\frac{N_Ahc}{\lambda}

where,

\lambda = Wavelength of the complex = 440nm=4.40\times 10^{-7}m    (Conversion factor:  1m=10^9nm )

h = Planck's constant = 6.624\times 10^{-34}Js

c = speed of light = 3\times 10^8m/s

N_A = Avogadro's number = 6.022\times 10^{23}

\Delta E = energy of the complex

Putting values in above equation, we get:

\Delta E=\frac{6.022\times 10^{23}\times 6.624\times 10^{-34}\times 3\times 10^8}{4.40\times 10^{-7}}\\\\\Delta E=2.72\times 10^{5}J=2.72\times 10^2kJ

Conversion factor used:  1 kJ = 1000 J

Hence, the energy of the complex is 2.72\times 10^2kJ

5 0
2 years ago
Two weak acids, A and B, have pKa values of 4 and 6, respectively. Which statement is true?A) Acid A dissociates to a greater ex
zalisa [80]

Answer:

A) Acid A dissociates to a greater extent in water than acid B

Explanation:

A) Acid A dissociates to a greater extent in water than acid B

We are given the pKa for both acids, and we know

pKa = - log Ka

Taking antilog to both sides of the equation we can solve for Ka

⇒ -pKa = log Ka

-antilog pKa = Ka

10 ^-pka = Ka

So ka for acid A = 10⁻⁴

and

ka for acid B = 10⁻⁶

True the equilibrium constant for acid A is greater, so it dissociates more.

B) For solutions of equal concentration, acid B will have a lower pH.

We know the stronger acid is A, and it dissociates more. Since pH is the negative log of H₃O⁺ concentration, it follows that at equal concentrations the acid A will have at equilibrium a greater [H₃O⁺] and hence a lower pH

C) B is the conjugate base of A

False:

If B were the conjugate base of A, its  Kb would have been given by:

Ka x Kb = Kw

Kb = 10⁻¹⁴/10⁻⁶ = 10⁻⁸ for the conjugate base of acid B

Kb = 10⁻¹⁴/10⁻⁴ = 10⁻¹⁰ for the conjugate base of acid A

which are not equal.

D) Acid A is more likely to be a polyprotic acid than acid B.

False

Just having the pkas for both acids one cannot know if any of the acids is polyprotic. We will need the formula for the acids.

E) The equivalence point of acid A is higher than that of acid B

False

The equivalence point depends on the the concentration of the acids  and their volumes.

The equivalence point is reached in the titration when the number of equivalents of base equals the number of equivalents of acid:

# equivalents acid = # equivalents of base  @ end point

and

# equivalents acid = Molarity of acid x Volume of acid

4 0
2 years ago
A chemical reaction is done in the setup shown , resulting in a change of mass. What will happen if the same reaction is done in
irina1246 [14]
<h2>Answer:</h2>

The mass of the system will remain the same if there is no conversion of mass to energy in the reaction.

<h3>Explanation:</h3>
  • If the system is closed, then according to the law of mass conservation the mass of the reaction system will remain the same.
  • <u><em>Law of conservation of the mass: In simple words, it is described as the mass of a closed system can never be changed, it may transfer from one form to another or change into energy.</em></u>
  • But if the reaction involves energy transfer like heat or light production, in this case, the mass can be changed.
5 0
2 years ago
Read 2 more answers
Consider the skeletal structure of naphthalein (C10H8), the active ingredient in mothballs. How many double bonds must be added
Greeley [361]

Answer:

four (4)

Explanation:

Naphthalein is an organic compound with formula C 10H 8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs.

The molecule is planar, like benzene. Unlike benzene, the carbon–carbon bonds in naphthalene are not of the same length. The bonds C1−C2, C3−C4, C5−C6 and C7−C8 are about 1.37 Å (137 pm) in length, whereas the other carbon–carbon bonds are about 1.42 Å (142 pm) long. This difference, established by X-ray diffraction is consistent with the valence bond model in naphthalene and in particular, with the theorem of cross-conjugation. This theorem would describe naphthalene as an aromatic benzene unit bonded to a diene but not extensively conjugated to it (at least in the ground state), which is consistent with two of its three resonance structures.

Because of this resonance, the molecule has bilateral symmetry across the plane of the shared carbon pair, as well as across the plane that bisects bonds C2-C3 and C6-C7, and across the plane of the carbon atoms. Thus there are two sets of equivalent hydrogen atoms: the alpha positions, numbered 1, 4, 5, and 8, and the beta positions, 2, 3, 6, and 7. Two isomers are then possible for mono-substituted naphthalenes, corresponding to substitution at an alpha or beta position. Bicyclo[6.2.0]decapentaene is a structural isomer with a fused 4–8 ring system.

Therefore four (4) double bonds will be added to give each carbon atom an octet structure.

8 0
2 years ago
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