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3 years ago

What happens if you don't use enough solvent for a recrystallization?

1 answer:

6 0

<span>With too little solvent, recrystallization occurs too quickly due to massive nucleation upon the flask becoming cooler. The crystals do not grow fully in this shortened period of time, as the solvent precipitates before the reaction is complete. Nucleation of the crystals also means more impurities in the final product.. .</span>

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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

5 0

3 years ago

A student plots the magnetic field of a bar magnet using a compass the student centers the bar magnet in the middle of a piece o

olga55 [171]

The diagram best shows the magnetic field around the bar magnet is the diagram in option B.

<h3>What is the magnetic field?</h3>

The magnetic field refers to the region in space where the influence of a magnet can be felt. We know that strength of magnet can be seen by following the magnetic lines of force. The more the magnetic lines of force, the stronger the magnetic field especially when the line are packed closely together.

Looking at the diagrams of the magnetic lines of force, it must be recalled that the magnetic lines of force runs from the north pole to the south pole and not the other way round.

Thus, the diagram best shows the magnetic field around the bar magnet is the diagram in option B.

Learn more about magnetic field:brainly.com/question/14848188

#SPJ1

4 0

1 year ago

Behavior (defense mechanisms)definition

Gekata [30.6K]

A variety of usually unconscious mental processes used to protect oneself from shame, anxiety, loss of self-esteem, conflict, or other unacceptable feelings or thoughts, and including behaviors<span> such as repression, projection, denial, and rationalization.

(google)</span>

7 0

3 years ago

The melting points of four impure samples of lead(II) bromide were measured. The results are

CaHeK987 [17]

Answer:

372

373

Explanation:

4 0

3 years ago

Which of the four models represents a solid

ICE Princess25 [194]

Answer:

is there an image

Explanation:

6 0

3 years ago