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konstantin123 [22]
2 years ago
9

When 16.0 g of an unknown compound (a nonelectrolyte) are dis solved in exactly 800. g of water, the solution has a freezing poi

nt of – 0.14 ° C. What is the molar mass of the compound? K f of water is 1.86 ° C m – 1 . A. 266 g B. 343 g C. 178 g D. 99.2 g E. 426 g _________________________________________________________
Chemistry
1 answer:
dexar [7]2 years ago
3 0

Answer:

A. 266g/mol

Explanation:

A colligative property of matter is freezing point depression. The formula is:

ΔT = i×Kf×m <em>(1)</em>

Where:

ΔT is change in temperature (0°C - -0,14°C = 0,14°C)i is Van't Hoff factor (1 for a nonelectrolyte dissolved in water), kf is freezing point molar constant of solvent (1,86°Cm⁻¹) and m is molality of the solution (moles of solute per kg of solution). The mass of the solution is 816,0g

Replacing in (1):

0,14°C = 1×1,86°Cm⁻¹× mol Solute / 0,816kg

<em>0,0614 = mol of solute</em>.

As molar mass is defined as grams per mole of substance and the compound weights 16,0g:

16,0g / 0,0614 mol = 261 g/mol ≈ <em>A. 266g/mol</em>

I hope it helps!

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AysviL [449]

Answer:

The answer is in the explanation

Explanation:

Acetic acid, CH₃COOH, is a weak acid that will produce a buffer when its conjugate base, CH₃COO⁻, acetate ion, is added to the solution.

<em>That is because a buffer is the mixture of a weak acid and its conjugate base or vice versa.</em>

When an acid (HX) is added to the solution, the acetate ion will react producing acetic acid, thus:

CH₃COO⁻ + HX → CH₃COOH + X⁻

For this reason, the pH doesn't change abruptly because H⁺ ions are not produced.

Now, if a  base (BOH) is added to the buffer, CH₃COOH will react producing acetate ion and water, thus:

CH₃COOH + BOH → CH₃COO⁻ + H₂O + B⁺.

In the same way, there are not produced free OH⁻ and the pH doesn't change significantly.

5 0
3 years ago
What is the overall reaction order for this rate law: rate = k[A]2[B][C]?
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Zero order are reactions in which concentration of reactant has NO effect on RATE OF REACTION.


2. First order are reactions in which concentration of one reactant is proportionate to the RATE OF REACTION.

Exp: That means when you increase the concentration of the one reactant, then the rate of reaction will increase by the same degree of extent.


3. Second order are reactions in which concentration of two reactant has an effect on the RATE OF REACTION.


Formula:

1. Zero order Rate = k

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where () represents concentration

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8 0
3 years ago
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What element in the second period has the largest atomic radius?
madreJ [45]

Answer:

b. lithium

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furthest to the left in second period

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Arrange the following H atom electron transitions in order of decreasing wavelength of the photon absorbed or emitted:
Katyanochek1 [597]

The decreasing order of wavelengths of the photons emitted or absorbed by the H atom is : b → c → a → d

Rydberg's formula :

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where  λ is the wavelength of the photon emitted or absorbed from an H atom electron transition from n_1 to n_2 and R_h = 109677 is the Rydberg Constant. Here n_1 and  n_2 represents the transitions.

(a) n_1 =2 to n_2 = infinity

            \frac{1}{\lambda} = 109677\times (\frac{1}{2^2}-\frac{1}{\infty^2}  ) = 109677/4     [since 1/infinity = 0] Therefore, \lambda = 4 / 109677 = 0.00003647 m

(b) n_1=4 to  n_2 = 20

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Therefore,  \lambda = 1 / 6580.62 = 0.000152 m

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(d)  n_1=2 to  n_2 = 1

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Therefore,  \lambda = 1 /82257.75  = - 0.0000121 m  

[Even though there is a negative sign, the magnitude is only considered because the sign denotes that energy is emitted.]

So the decreasing order of wavelength of the photon absorbed or emitted is b → c → a → d.

Learn more about the Rydberg's formula athttps://brainly.com/question/14649374

#SPJ4

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Hence option B is correct.

Hope this helps!
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