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3 years ago

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PLEASE HELP!!! The gold foil Rutherford used in his scattering experiment had a thickness of approximately 4×10−3 mm . If a sing

le gold atom has a diameter of 2.9×10−8 cm, how many atoms thick was Rutherford's foil?

2 answers:

san4es73 [151]3 years ago

8 0

Answer : the number of gold atoms is 1.38 ×10^5

Ilya [14]3 years ago

3 0

Answer:

16 atoms thick

Explanation:

4*10-3= 37

2.9*10-8=21

37-21=16

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A solution of 0.0470 M HCl is used to titrate 26.0 mL of an ammonia solution of unknown concentration. The equivalence point is

DanielleElmas [232]

The pH at equivalence point is 12.46

At equivalence point, number of moles of acid, n equals number of moles of base, n'

So, n = n'

CV = C'V' where

C = concentration of acid (HCl) = 0.0470 M,
V = volume of acid = 16.0 mL,
C' = concentration of base (ammonia solution) and
V' = volume of base = 26.0 mL.

<h3>Concentration of ammonia solution</h3>

Making C' subject of the formula, we have

C' = CV/V'

Substituting the values of the variables into the equation, we have

C' = CV/V'

C' = 0.0470 M × 16.0 mL/26.0 mL

C' = 0.752 MmL/26.0 mL

C' = 0.0289 M

<h3>The concentration of acid at equivalence point</h3>

We know that the ion-product of water Kw is

Kw = [H⁺][OH⁻] = where

[H⁺] = concentration of HCl at equivalence point,
[OH⁻] = C' = concentration of ammonia solution = 0.0289 M and
Kw = 1.01 × 10⁻¹⁴

Making [H⁺] subject of the formula, we have

[H⁺} = Kw/[OH⁻]

[H⁺] = 1.01 × 10⁻¹⁴/0.0289

[H⁺] = 34.95 × 10⁻¹⁴

[H⁺] = 3.495 × 10⁻¹³

<h3>pH at equivalence point</h3>

Since pH = -㏒[H⁺]

pH = -㏒[3.495 × 10⁻¹³]

pH = -㏒[3.495] + (-㏒10⁻¹³)

pH = -㏒[3.495] + [-13(-㏒10)]

pH = 13 - 0.5434

pH = 12.4566

pH ≅ 12.46

So, the pH at equivalence point is 12.46

Learn more about pH at equivalence point here:

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2 years ago

Please help me with my science thank you!

Tatiana [17]

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Which material is the lest likely to be recognized as a mixture by looking at it under a microscope ?

Lisa [10]

Hello,

The answer is option C <span>homogeneous mixture.

Reason:

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If you need anymore help feel free to ask me!

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4 years ago

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Someone please help!!!

sveticcg [70]

Answer: The last electron will be filled in first orbital of 3p sub-shell.

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