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Contact [7]
2 years ago
11

Help me please somebody ??

Chemistry
1 answer:
Hunter-Best [27]2 years ago
7 0
The average mass of all the isoptopes of an element :)
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For the reaction: CH3NH2(aq) + H2O(aq) ⇌ CH3NH3 +(aq) + OH- Determine the change in the pH (ΔpH) for the addition of 6.7 M CH3NH
Korolek [52]

Answer:

The change in the pH (ΔpH) is 2,17

Explanation:

The reaction:

CH₃NH₂(aq) + H₂O(aq) ⇌ CH₃NH₃⁺(aq) + OH⁻

kb = \frac{[OH^{-}][CH_{3}NH_{3}^+]}{[CH_{3}NH_{2}]} <em>(1)</em>

In equilibrium, a solution of CH₃NH₂ 4,7M produces:

[CH₃NH₂] = 4,7 - x

[CH₃NH₃⁺] = x

[OH⁻] = x

Replacing in (1):

4,38x10^{-4} = \frac{x^2}{4,7-x}

x² + 4,38x10⁻⁴x - 2,0586x10⁻³ = 0

The solutions are:

x = -0,0456 No physical sense. There are not negative concentrations.

x = 0,04515 Real answer.

The concentration of [OH⁻] is 0,04515 M.

As pOH = -log [OH⁻] And pH+pOH = 14. The pH of this solution is:

<em>pH = 12,65</em>

The addition of 6,7M produce this changes in concentrations:

[CH₃NH₂] = 4,656 + x

[CH₃NH₃⁺] = 6,74515 - x

[OH⁻] = 0,04515 - x

Replacing in (1) you will obtain:

x² - 6,7907x + 0,3025 = 0

Solving for x:

x = 6,74586 No physical sense

x = 0,04484 Real answer.

Thus, [OH⁻] = 0,04515 - 0,044842 = 3,08x10⁻⁴M

pOH = 3,51.

<em>pH = 10,49</em>

Thus ΔpH is 12,65 - 10,49 = <em>2,16 ≈ 2,17</em>

I hope it helps!

4 0
3 years ago
Does the mass of water increase or decrease when it changes to ice
NikAS [45]

Answer:

The mass stays the same only volume changes, the volume decreases

Explanation:

The ice shrinks (decreases volume) and becomes more dense. The weight will not (and cannot) change.

4 0
3 years ago
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valentinak56 [21]
100M solution so did new wells alanna annan carbonated
3 0
2 years ago
What is the area of a square
evablogger [386]

Answer: base times height

Explanation:

8 0
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Please list about 10 facts about viscosity
MariettaO [177]
Viscosity is the thickness of a liquid, cause by the friction between the molecules in that liquid. A very high viscosity would result in a solid form and low would be a liquid. If a liquid as zero viscosity is only found in superfluids at there freezing points or lower. There are also two types of viscosity “dynamic” (which is measure in seconds, pascal seconds to be exact) and “kinematic” (which is measured in metre per second squared)

Fun fact they use viscosity to predict when volcanoes are going to erupt:)

Hope this helps I love sciencey stuff so if you need anymore help let me know!
5 0
2 years ago
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