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3 years ago

What is the base dissociation constant for a weak base at equilibrium, B + H2O <===> BH+ + OH–?

Chemistry

2 answers:

enot [183]3 years ago

8 0

Answer: The base dissociation constant for the equation is $K_b=\frac{[BH^=][OH^-]}{[B]}$

Explanation:

Base dissociation constant, $K_b$ exists when a weak base is dissolved in water. It is expressed as the ratio of molar concentration of the products and the molar concentration of the reactants raised to power their respective stoichiometric coefficients.

For the dissociation of a weak base, the equation follows:

$B+H_2O\rightarrow BH^++OH^-$

The equilibrium constant for the above equation:

$K_{eq}=\frac{[BH^=][OH^-]}{[B][H_2O]}$

Concentration of water is very large and is taken as constant.

$K_{eq}\times [H_2O]=\frac{[BH^=][OH^-]}{[B]}$

Hence, the equation becomes:

$K_b=\frac{[BH^=][OH^-]}{[B]}$

podryga [215]3 years ago

3 0

Depends on what the base is. You would reference the base dissociation chart for that value.

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The molecular weight of a gas is ________ g/mol if 3.5 g of the gas occupies 2.1 l at stp

bija089 [108]

Pre-1982 definition of STP: 37 g/mol Post-1982 definition of STP: 38 g/mol This problem is somewhat ambiguous because the definition of STP changed in 1982. Prior to 1982, the definition was 273.15 K at a pressure of 1 atmosphere (101325 Pascals). Since 1982, the definition is 273.15 K at a pressure of exactly 100000 Pascals). Because of those 2 different definitions, the volume of 1 mole of gas is either 22.414 Liters (pre 1982 definition), or 22.71098 liters (post 1982 definition). And finally, there's entirely too many text books out there that still use the 35 year obsolete definition. So let's solve this problem using both definitions and you need to pick the correct answer for the text book you're using. First, determine how many moles of gas you have. Just simply divide the volume you have by the molar volume. Pre-1982: 2.1 / 22.414 = 0.093691443 moles Post-1982: 2.1 / 22.71098 = 0.092466287 moles Now determine the molar mass. Simply divide the mass by the moles. So Pre-1982: 3.5 g / 0.093691443 moles = 37.35666667 g/mol Post-1982: 3.5 g / 0.092466287 moles = 37.85163333 g/mol Finally, round to 2 significant figures. So Pre-1982: 37 g/mol Post-1982: 38 g/mol

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3 years ago

Kenya has a pile of salt on the counter. She uses a pinch of it for a meal. Which of the following physical properties of the sa

AlladinOne [14]

The following choices are all extensive properties, meaning they do not change with the amount of the substance. Although, 3 of the properties, namely, density, solubility and thermal conductivity are temperature-dependent. Since the problem did not mention of heating, let's assume Kenya just used it directly for her meal. Among the choices, I think shape would change. Once you place it in the meal, you can no longer pinpoint the salt because it's shape has been changed.

7 0

3 years ago

Read 2 more answers

Are C-12, C-13, and C-14 all carbon isotopes?

kramer

Answer:

Yes, they are isotopes.

Explanation:

Isotopes are atoms with the same atomic number Z and a different mass number (A). That is, they differ in the number of neutrons (eg carbon 12, has 6 protons, 6 electrons, and 6 neutrons, carbon 13, 7 neutrons, and carbon 14 8 neutrons).

3 0

3 years ago

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Gastric juice is made up of substances secreted from parietal cells, chief cells, and mucous-secreting cells. The cells secrete

neonofarm [45]

Answer:

The amount of energy required to transport hydrogen ions from a cell into the stomach is 37.26KJ/mol.

Explanation:

The free change for the process can be written in terms of its equilibrium constant as:

ΔG° = $-RTInK_(eq)$

where:

R= universal gas constant

T= temperature

$K_eq$ = equilibrum constant for the process

Similarly, free energy change and cell potentia; are related to each other as follows;

ΔG= -nFE°

from above;

F = faraday's constant

n = number of electrons exchanged in the process; and

E = standard cell potential

∴ The amount of energy required for transport of hydrogen ions from a cell into stomach lumen can be calculated as:

ΔG° = $-RTInK_(eq)$

where;

[texK_eq[/tex]= $\frac{[H^+]_(cell)}{[H^+(stomach lumen)]}$

For transport of ions to an internal pH of 7.4, the transport taking place can be given as:

$H^+_{inside}$ ⇒ $H^+_{outside}$

Equilibrum constant for the transport is given as:

$K_{eq}=\frac{[H^+]_{outside}}{[H^+]_{inside}}$

$=\frac{[H^+]_{cell}}{[H^+]_{stomach lumen}}$

$[H^+]_{cell}$ = 10⁻⁷⁴

=3.98 * 10⁻⁸M

$[H^+]_{stomach lumen}$ = 10⁻²¹

=7.94 * 10⁻³M

Hence;

$K_{eq}=\frac{[H^+]_{cell}}{[H^+]_{stomachlumen}}$

= $\frac{3.98*10^{-8}}{7.94*10{-3}}$

= 5.012 × 10⁻⁶

Furthermore, free energy change for this reaction is related to the equilibrium concentration given as:

ΔG° = $-RTInK_(eq)$

If temperature T= 37° C ; in kelvin

=37° C + 273.15K

=310.15K; and

R-= 8.314 j/mol/k

substituting the values into the equation we have;

ΔG₁ = $-(8.314J/mol/K)(310.15)TIn(5.0126*10^{-6})$

= 31467.93Jmol⁻¹

≅ 31.47KJmol⁻¹

If the potential difference across the cell membrane= 60.0mV.

Energy required to cross the cell membrane will be:

ΔG₂ = $-nFE°_{membrane}$

ΔG₂ = $-(1 mol)(96.5KJ/mol/V)(60*10^{-3})$

= 5.79KJ

Therefore, for one mole of electron transfer across the membrane; the energy required is 5.79KJmol⁻¹

Now, we can calculate the total amount of energyy required to transport H⁺ ions across the membrane:

Δ $G_{total} = G_{1}+G_{2}$

= (31.47+5.79) KJmol⁻¹

= 37.26KJmol⁻¹

We can therefore conclude that;

The amount of energy required to transport ions from cell to stomach lumen is 37.26KJmol⁻¹

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3 years ago

When might a dominant trait appear?

daser333 [38]

Answer:

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Explanation:

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<) )╯all the single ladies

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3 years ago