The pH of a solution is 6.5 . What Is the pOH

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about 4.4x 10 m/s Calculate the

otez555 [7]

The question is incomplete, here is the complete question:

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about $4.4\times 10^6m/s$ . Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of helium. Write your answer as a percentage of the average speed, and round it to 2 significant digits

<u>Answer:</u> The percentage of average speed is 41 %

<u>Explanation:</u>

We are given:

Radius of helium atom = 31 pm = $31\times 10^{-12}m$ (Conversion factor: $1m=10^{12}pm$ )

So, diameter of helium atom = $(2\times r)=(2\times 31\times 10^{-12})=64\times 10^{-12}m$

The diameter of the atom will be equal to the uncertainty in position.

The equation representing Heisenberg's uncertainty principle follows:

$\Delta x.\Delta p=\frac{h}{2\pi}$

where,

$\Delta x$ = uncertainty in position = d = $64\times 10^{-12}m$

$\Delta p$ = uncertainty in momentum = $m\Delta v$

m = mass of electron = $9.1095\times 10^{-31}kg$

h = Planck's constant = $6.627\times 10^{-34}kgm^2/s^2$

Putting values in above equation, we get:

$64\times 10^{-12}m\times 9.1095\times 10^{-31}kg\times \Delta v=\frac{6.627\times 10^{-34}kgm^2/s}{2\times 3.14}\\\\\Delta v=\frac{6.627\times 10^{-34}kgm^2/s^2}{2\times 3.14\times 64\times 10^{-12}m\times 9.1095\times 10^{-31}kg}=1.81\times 10^6m/s$

To calculate the percentage of average speed, we use the equation:

$\text{Percentage of the average speed}=\frac{\text{Uncertainty in velocity}}{\text{Average orbital speed}}\times 100$

We are given:

Average orbital speed = $4.4\times 10^6m/s$

Putting values in above equation, we get:

$\text{Percentage of the average speed}=\frac{1.81\times 10^6m/s}{4.4\times 10^6m/s}\times 100\\\\\text{Percentage of the average speed}=41.\%$

Hence, the percentage of average speed is 41 %

3 0

4 years ago

Read the list of elements given below. Be, Mg, Ca, Sr Which of the following about the elements is true? (5 points)

slava [35]

Answer:

Pretty Sure Its A

Explanation:

4 0

3 years ago

A sample of gas has an initial volume of 22.6 L at a pressure of 1.67 atm. If the sample is compressed to a volume of 10.0 L : ,

Sphinxa [80]

Answer:

3.74 atmospheres

Explanation:

If the temperature is constant, then the formula is

V*P = V1 * P1

V = 22.6 L

P = 1.67 atm

V1 = 10.0 L

P1 = ??

=============

22.6 * 1.67 = 10 * P1

37.742 = 10 * P1

37.742/10 = P1

P1 = 3.742

Note there are 3 sig digs in each given, so the answer should be

P1 = 3.74 atmospheres

8 0

3 years ago

Calculate the pH of 500cm3 of 0.2mol/dm3 Ca(OH2), assume complete ionisation

Lilit [14]

Answer:

The pH of 500 cm³, 0.2 mol/dm³, Ca(OH₂) is ≈ 13.6

Explanation:

The given parameters are;

Concentration of the calcium hydroxide, Ca(OH₂) = 0.2 mol/dm³

Volume of the calcium hydroxide, Ca(OH₂) = 500 cm³

Given that the calcium hydroxide, Ca(OH₂), undergoes complete ionization in water, complete dissociation, we have;

Ca(OH₂) ⇄ Ca²⁺ + 2 OH⁻

Therefore, we have;

2 moles of [OH⁻] for each mole of Ca(OH₂) which gives the concentration of [OH⁻] as

[OH⁻] = 2 × 0.2 ≈ 0.4 mol/dm³

The pH is given by the formula

pH = 14 + ㏒₁₀ [OH⁻]

pH = 14 + ㏒₁₀ (0.4) = 14 - 0.3979 = 13.6021 ≈ 13.6

The pH of the 500 cm³ 0.2 mol/dm³ Ca(OH₂) ≈ 13.6.

4 0

3 years ago

Which 3 laws combine to make the Combined Gas Law?

lions [1.4K]

Answer:

Boyle's Law, Charles' Law, and Gay-Lussac's Law

Explanation:

3 0

3 years ago

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