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3 years ago

Find the pH and fraction of association of a 0.100 M solution of the weak base B with Kb = 1.00 x 10^5.

Chemistry

1 answer:

aev [14]3 years ago

4 0

Answer:

Fraction of association = 0.01

pH = 11

Explanation:

A weak base, B, is in equilibrium with water as follows:

B(aq) + H2O(l) ⇄ BH⁺(aq) + OH⁻(aq)

Where Kb is defined as:

Kb = 1.00x10⁻⁵ = [BH⁺] [OH⁻] / [B]

Some B will react producing BH⁺ and OH⁻:

[BH⁺] = X

[OH⁻] = X

[B] = 0.100M - X

As Kb <<< [B] we can say:

[B] ≈ 0.100M

Replacing:

1.00x10⁻⁵ = [X] [X] / [0.100]

1.00x10⁻⁶ = X²

X = 1x10⁻³M = [BH⁺] = [OH⁻]

The fraction of association is [BH⁺] / [B] = 1x10⁻³M / 0.100M = 0.01

As [OH⁻] = 1x10⁻³M, pOH = -log[OH⁻] = 3

pH = 14- pOH

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An energy of 6.8 x 10^-19 J/atom is required to cause an aluminum atom on a metal surface to lose an electron.

Nana76 [90]

Wavelength of the light is 2.9 × 10⁻⁷ m.

Explanation:

Planck - Einstein equation shows the relationship between the energy of a photon and its frequency, and they are directly proportional to each other and it is given by the equation as E = hν,

where E is the energy of the photon

h is the Planck's constant = 6.626 × 10⁻³⁴ J s

ν is the frequency

From the above equation, we can find the frequency by rearranging the equation as,

ν = $$ \frac{E}{h}$ = $$ \frac{6.8 \times 10^{-19}}{6.626\times10^{-34}} = 1.03\times10^{15} s^{-1}$

Now the frequency and the wavelength are in inverse relationship with each other.

ν × λ = c

It can be rearranged to get λ as,

λ = c / ν

= $$\frac{3\times 10^{8} ms^{-1}}{1.03\times10^{15}s^{-1}} = 2.9\times 10^{-7} m$

So wavelength is 2.9 × 10⁻⁷ m.

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4 years ago

An element has two isotopes. One has a mass of 5.03 amu and an abundance of 25%, the other has a mass of 7.20 amu and an

pav-90 [236]

Answer:

Average atomic mass = 6.6575.

Explanation:

As fractions the abundance is 1/4 and 3/4.

The average atomic mass = (5.03 + 3(7.20) / 4

= 6.6575.

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3 years ago

Describing the Rock Cycle

Alex17521 [72]

Answer:

A, C, and D

Explanation:

A-Any type of rock can change into any other type of rock by weathering and erosion.

C-Rocks change slowly over time.

D- The rock cycle shows how the three rock types relate to one another.

Its correct on edge

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4 years ago

Read 2 more answers

Bromine has a charge of__ when it has 36 electrons.

Elan Coil [88]

Explanation :

Actually bromine have 35 electrons when it is neutral, and if the number of electrons is increased by 1 it gains a relative negative charge of 1.

Also written as : -1

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3 years ago

4. Al2O3 (s) + 6HCl (aq) → 2AlCl3 (aq) + 3H20(1) Find the mass of AlCl3 that is produced when 10.0 grams of Al2O3 react with 10.

slava [35]

Answer:

Are produced 12,1 g of AlCl₃ and 5,33 g of Al₂O₃ are left over

Explanation:

For the reaction:

Al₂O₃ (s) + 6 HCl (aq) → 2AlCl₃ (aq) + 3H₂0(l)

10,0g of Al₂O₃ are:

10,0g ₓ $\frac{1mol}{102g}$ = 0,0980 moles

And 10,0g of HCl are:

10,0 gₓ $\frac{1mol}{36,5g}$ = 0,274 moles

For a total reaction of 0,274 moles of HCl you need:

0,274× $\frac{1molesAl_{2}O_3}{6 mole HCl}$ = 0,0457 moles of Al₂O₃

Thus, limiting reactant is HCl

The grams produced of AlCl₃ are:

0,274 moles HCl × $\frac{2 moles AlCl_{3}}{6 moles HCl}$ × 133 $\frac{g}{mol}$ = 12,1 g of AlCl₃

The moles of Al₂O₃ that don't react are:

0,0980 moles - 0,0457 moles = 0,0523 moles

And its mass is:

0,0523 molesₓ $\frac{102g}{1mol}$ = 5,33 g of Al₂O₃

I hope it helps!

7 0

3 years ago