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motikmotik
3 years ago
10

What is the percent composition of the following *KBr *LiOH *Mgl2 *Al2(SO4)3

Chemistry
1 answer:
schepotkina [342]3 years ago
4 0
For the first one, K is 32.85% and Br is 67.14%
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What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.0×1015Hz?
RideAnS [48]

The kinetic energy of the emitted electrons of cesium when it is exposed to UV rays of frequency 1.0 \times {10^{15}}\;{\text{Hz}}  is  \boxed{6.63 \times {{10}^{ - 19}}\;{\text{J}}}

Further Explanation:

Photoelectric effect:

When light is made to fall on any substance, electrons are emitted from it. This is known as the photoelectric effect and the emitted electrons are called photoelectrons. The electrons are emitted because of the transference of energy from light to the electrons.

Cesium is a member of the alkali metal group so it is highly reactive and shows photoelectric effect to the maximum extent. It can remove its electron so easily because of its atomic size. Due to large atomic size of cesium, its outermost electrons are held very less tightly to the nucleus and therefore removed easily.

According to the Planck-Einstein equation, the energy is proportional to the frequency and is expressed as follows:

{\mathbf{E=h\nu }}                                   ......(1)

Here,

{\text{E}} is the energy.

h is the Plank’s constant.

\nu is the frequency.

The frequency of UV rays is 1.0 \times {10^{15}}\;{\text{Hz}} or 1.0 \times {10^{15}}\;{{\text{s}}^{ - 1}}

The value of Planck’s constant is 6.626 \times {10^{ - 34}}\;{\text{J}}\cdot{\text{s}} .

Substitute these values in equation (1)

\begin{aligned}{\text{E}}&=\left( {6.626 \times {{10}^{ - 34}}\;{\text{J}}\cdot{\text{s}}}\right)\left( {1.0 \times {{10}^{15}}\;{{\text{s}}^{ - 1}}}\right)\\&=6.63\times {10^{ - 19}}\;{\text{J}}\\\end{aligned}

But when electrons are ejected out from the surface of the substance, all of its energy is considered as kinetic energy.

So the kinetic energy of the electrons is {\mathbf{6}}{\mathbf{.63 \times 1}}{{\mathbf{0}}^{{\mathbf{ - 19}}}}\;{\mathbf{J}} .

Learn more:

1. Statement about subatomic particle: brainly.com/question/3176193

2. The energy of a photon in light: brainly.com/question/7590814

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Structure of the atom

Keywords: kinetic energy, frequency, energy, photoelectric effect, Planck's constant, light, electrons, photoelectrons, proportional, transference, reactive, cesium.

7 0
3 years ago
Read 2 more answers
Compounds can not be separated by Response area means. Separating a compound requires a Response areareaction.
Aleks04 [339]

Answer:

use vinager

Explanation:

I did this heh :/

7 0
3 years ago
2/10
emmainna [20.7K]

Answer:

pH=2.34

Explanation:

HBr  -> H  + Br

The dissociation it's complete, for that reason the concentration of the products is the same of HBr

[H+]=[Br-]=0.00234 M

pH= - log (0.00234)=2.34

6 0
3 years ago
If 22.5L of nitrogen at 748 mm Hg are compressed to 725 mm Hg at constant temperature. What is the new volume?2.A gas with a vol
kykrilka [37]

Answer:

a)23.2 L

b)68.3kPa

c)7.5 atm

d)60.5L

e)1.67 atm

Explanation:

From Boyle's law:

P1V1=P2V2

P1= 748mmHg

P2=725mmHg

V1= 22.5L

V2??

V2= P1V1/P2= 748×22.5/725= 23.2 L

b)

V1=4.0L

P1= 205×10^3Pa

V2= 12.0L

P2=???

P2= P1V1/V2= 205×10^3×4/12

P2= 68.3×10^3 Pa or 68.3kPa

c)

P1= 1 atm

V1= 196.0L

P2= ??

V2= 26.0L

P2= P1V1/V2=1×196.0/26.0

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d)

V1= 40.0L

P1= 12.7×10^3Pa

V2=???

P2= 8.4×103Pa

V2= P1V1/P2= 12.7×10^3×40.0/8.4×103

V2=60.5L

e)

V1= 100mL

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V2= 60mL

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P2= P1V1/V2= 1×100/60

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3 years ago
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