Need help with the following

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

Be sure to answer all parts. For each reaction, find the value of ΔSo. Report the value with the appropriate sign. (a) 3 NO2(g)

Liono4ka [1.6K]

Answer:

a. -268.13 J/K

b. -279.95 J/K

c. + 972.59 J/K

Explanation:

The value of the change in entropy (ΔS°) can be calculated by:

ΔS° = ∑n*S° products - ∑n*S° reactants, where n is the stoichiometric number of moles.

The values of S° for each substance can be found on a thermodynamic table.

a. 3NO2(g) + H2O(l) → 2HNO3(l) + NO(g)

S°, NO2(g) = 240.06 J/mol.K

S°, H2O(l) = 69.91 J/mol.K

S°, HNO3(l) = 155.60 J/mol.K

S°, NO(g) = 210.76 J/mol.K

ΔS° = (210.76 + 2*155.60) - (3*240.06 + 69.91)

ΔS° = -268.13 J/K

b. N2(g) + 3F2(g) → 2NF3(g)

S°, N2(g) = 191.61 J/mol.K

S°, F2(g) = 202.78 J/mol.K

S°, NF3(g) = 260.0 J/mol.K

ΔS° = (2*260.0 ) - (191.61 + 3*202.78)

ΔS° = -279.95 J/K

c. C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(g)

S°, C6H12O6(s) = 212 J/mol.K

S°, O2(g) = 205.138 J/mol.K

S°, CO2(g) = 213.74 J/mol.K

S°, H2O(g) = 188.83 J/mol.K

ΔS° = (6*213.74 + 6*188.83) - (212 + 6*205.138)

ΔS° = +972.59 J/K

3 0

2 years ago

A sample of gasoline contains various hydrocarbons, which comprise atoms of carbon, hydrogen, and oxygen. The hydrocarbons mix t

Naddika [18.5K]

Answer:

mixture
homogenous mixture (of hydrocarbons)
compound

Explanation:

Mixture can be easily separated by physical methods. Homogeneity and heterogeneity of a mixture is determined by whether the components there in are in a single phase and evenly distributed or not.

A solution has a solute evenly dissolved in solvent to form a liquid substance.

An element is the basic form of substance which cannot be broke down into any other simpler unit.

I hope this was helpful.

4 0

2 years ago

Acidosis is a human body disorder caused by too much acid in the stomach. If a patient was tested for this using their saliva an

Luden [163]

it will turn green or blue I think

8 0

2 years ago

Which undefined geometric term is described as a two-dimensional set of points that has no beginning or end?

adell [148]

Answer:

The two-dimensional set of points that has no beginning or end is described by the undefined geometric term plane.

Explanation:

There are three undefined terms in geometry:

point,
line, and
plane

They are referred as undefined terms because they are not defined in a formal way, i.e. using mathematically defined words. At the end these terms are abstractions (ideas).

The point has no dimensions, it can be represented by the tip of a sharp pencil.

The line is referred as an infinite set of joined points that extend indefinitely in one direction (from right to left, from north to south), so it has one dimension. The intersection of of two perpendicular walls is an example of what a line is.

Finally, the term to which the question is referred is the plane: an infinite set of joined points that extends in two dimensions. An example of plane is the surface of quite water. The plane does not have depth, only extension; that is why it has only two dimensions.

So, you should remember: points do not have dimensions, lines have one dimension, and planes have two dimensions.

8 0

2 years ago