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2 years ago

14

How many moles are there in 545g of

="latex-formula"> Fe₂0₃?

1 answer:

Pachacha [2.7K]2 years ago

8 0

answer: 3.40625 moles

Explanation: see the attached pics

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The work function for metallic potassium is 2.3 eV. Calculate the velocity in km/s for electrons ejected from a metallic potassi

mote1985 [20]

Answer:

932.44 km/s

Explanation:

Given that:

The work function of the magnesium = 2.3 eV

Energy in eV can be converted to energy in J as:

1 eV = 1.6022 × 10⁻¹⁹ J

So, work function = $2.3\times 1.6022\times 10^{-19}\ J=3.68506\times 10^{-19}\ J$

Using the equation for photoelectric effect as:

$E=\psi _0+\frac {1}{2}\times m\times v^2$

Also, $E=\frac {h\times c}{\lambda}$

Applying the equation as:

$\frac {h\times c}{\lambda}=\psi _0+\frac {1}{2}\times m\times v^2$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

m is the mass of electron having value $9.11\times 10^{-31}\ kg$

$\lambda$ is the wavelength of the light being bombarded

$\psi _0=Work\ function$

v is the velocity of electron

Given, $\lambda=260\ nm=260\times 10^{-9}\ m$

Thus, applying values as:

$\frac{6.626\times 10^{-34}\times 3\times 10^8}{260\times 10^{-9}}=3.68506\times 10^{-19}+\frac{1}{2}\times 9.11\times 10^{-31}\times v^2$

$3.68506\times \:10^{-19}+\frac{1}{2}\times \:9.11\times \:10^{-31}v^2=\frac{6.626\times \:10^{-34}\times \:3\times \:10^8}{260\times \:10^{-9}}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=7.64538\times 10^{-19}-3.68506\times 10^{-19}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=3.96032462\times 10^{-19}$

$v^2=0.869446\times 10^{12}$

v = 9.3244 × 10⁵ m/s

Also, 1 m = 0.001 km

<u>So, v = 932.44 km/s</u>

5 0

3 years ago

How many joules of energy are made by the loss of 100kg of mass using the formula E=mc2? please help!!!

asambeis [7]

Answer:

E = 3 × 10¹⁰ J

Explanation:

Mass, m = 100 kg

We need to find energy made by the loss of 100 kg of mass. The formula between the mass and energy is given by :

E = mc²

Where c is speed of light

Putting all the values, we get :

E = 100 kg × (3×10⁸ m/s)²

= 3 × 10¹⁰ J

So, the required energy is 3 × 10¹⁰ J.

6 0

3 years ago

As a substance changes from a liquid to a gas, the average distance between molecules..

dimulka [17.4K]

Answer: increases

Explanation:

Matter exists in three different states, they are solids, liquids and gases. And each of them contains molecules with a certain amount of kinetic energy.

Hence, the addition of heat changes a substance from a liquid to a gas through a process called vaporization, whereby liquid molecules on changing to gases acquire a higher kinetic energy, and move more freely within the containing vessel.

Thus, the higher kinetic energy explains the increase in the average distance between molecules.

8 0

3 years ago

A sample of an Iron Oxalato complex salt weighting 0.145 grams requires 34.88 mL of 0.015 M KMnO4 to turn the solution a very li

Amanda [17]

Answer:

5.2 ×10^-4 moles

Explanation:

Equation of reaction:

5C2O4^2- + 2MnO4^- +. 6H^+. ----------> 10CO2. +. 8H2O. + 2Mn^2+

From the information provided in the question:

Volume of potassium permanganate= 34.88ml

Concentration of potassium permanganate= 0.015M

Amount potassium permanganate= 0.015 × 34.88/1000= 5.2 ×10^-4 moles

6 0

3 years ago

Read 2 more answers

A sample of silicon rejected for use in an electronic circuit has an impurity of boron at a level of 3 parts per trillion. What

Law Incorporation [45]

Answer:

A. 3 x 10-12

Explanation:

Generally, the parts-per notation is used to represent very small concentration without any specific unit.

Parts per million is notated as $10^{-6}$

Parts per billion is notated as $10^{-9}$

Parts per trillion is notated as $10^{-12}$

Hence, 3 parts per trillion will be written as 3 x $10^{-12}$

The correct option is A.

6 0

3 years ago

Read 2 more answers