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3 years ago

Why does nuclear charge increase as you go left to right across a period

1 answer:

7 0

The atomic number increases moving left to right across a period and subsequently so does the effective nuclear charge. Therefore, moving left to right across a period the nucleus has a greater pull on the outer electrons and the atomic radii decreases.

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Mercury-203 undergoes beta minus decay. 203 80 hg → 203 81 tl ? the subatomic particle produced is a(n) . 203 80 hg → 203 81 tl

cricket20 [7]

The correct balanced equation of a beta decay undergone by Mercury-203 is as follows:

203 80 Hg → 203 81 + 0 -1 e

<h3>What is beta decay?</h3>

Beta decay in radioactivity refers to the release of a beta particle by a radioactive element.

Beta particle is characterized by the possession of mass number 0 and atomic number -1.

This means that if Mercury-203 undergoes beta decay, the atomic number of the resulting isotope will be +1 as follows:

203 80 Hg → 203 81 Tl + 0 -1 e

Learn more about beta radiation at: brainly.com/question/1580990

8 0

2 years ago

A voltaic cell consists of a Zn>Zn2+ half-cell and a Ni>Ni2+ half-cell at 25 °C. The initial concentrations of Ni2+ and Zn

nlexa [21]

Answer :

(a) The initial cell potential is, 0.53 V

(b) The cell potential when the concentration of $Ni^{2+}$ has fallen to 0.500 M is, 0.52 V

(c) The concentrations of $Ni^{2+}$ and $Zn^{2+}$ when the cell potential falls to 0.45 V are, 0.01 M and 1.59 M

Explanation :

The values of standard reduction electrode potential of the cell are:

$E^0_{[Ni^{2+}/Ni]}=-0.23V$

$E^0_{[Zn^{2+}/Zn]}=-0.76V$

From this we conclude that, the zinc (Zn) undergoes oxidation by loss of electrons and thus act as anode. Nickel (Ni) undergoes reduction by gain of electrons and thus act as cathode.

The half reaction will be:

Reaction at anode (oxidation) : $Zn\rightarrow Zn^{2+}+2e^-$ $E^0_{[Zn^{2+}/Zn]}=-0.76V$

Reaction at cathode (reduction) : $Ni^{2+}+2e^-\rightarrow Ni$ $E^0_{[Ni^{2+}/Ni]}=-0.23V$

The balanced cell reaction will be,

$Zn(s)+Ni^{2+}(aq)\rightarrow Zn^{2+}(aq)+Ni(s)$

First we have to calculate the standard electrode potential of the cell.

$E^o=E^o_{cathode}-E^o_{anode}$

$E^o=E^o_{[Ni^{2+}/Ni]}-E^o_{[Zn^{2+}/Zn]}$

$E^o=(-0.23V)-(-0.76V)=0.53V$

(a) Now we have to calculate the cell potential.

Using Nernest equation :

$E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Zn^{2+}]}{[Ni^{2+}]}$

where,

n = number of electrons in oxidation-reduction reaction = 2

$E_{cell}$ = emf of the cell = ?

Now put all the given values in the above equation, we get:

$E_{cell}=0.53-\frac{0.0592}{2}\log \frac{(0.100)}{(1.50)}$

$E_{cell}=0.49V$

(b) Now we have to calculate the cell potential when the concentration of $Ni^{2+}$ has fallen to 0.500 M.

New concentration of $Ni^{2+}$ = 1.50 - x = 0.500

x = 1 M

New concentration of $Zn^{2+}$ = 0.100 + x = 0.100 + 1 = 1.1 M

Using Nernest equation :

$E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Zn^{2+}]}{[Ni^{2+}]}$

Now put all the given values in the above equation, we get:

$E_{cell}=0.53-\frac{0.0592}{2}\log \frac{(1.1)}{(0.500)}$

$E_{cell}=0.52V$

(c) Now we have to calculate the concentrations of $Ni^{2+}$ and $Zn^{2+}$ when the cell potential falls to 0.45 V.

Using Nernest equation :

$E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Zn^{2+}+x]}{[Ni^{2+}-x]}$

Now put all the given values in the above equation, we get:

$0.45=0.53-\frac{0.0592}{2}\log \frac{(0.100+x)}{(1.50-x)}$

$x=1.49M$

The concentration of $Ni^{2+}$ = 1.50 - x = 1.50 - 1.49 = 0.01 M

The concentration of $Zn^{2+}$ = 0.100 + x = 0.100 + 1.49 = 1.59 M

5 0

3 years ago

How does water change when it is frozen?

vredina [299]

Answer:

the molecules of water contracts when it is frozen

7 0

3 years ago

How quick does it take for hearts to beat

serg [7]

very quick like 4 beats per seconed

6 0

3 years ago

The polar isopropanol molecules are attracted to

Sergio [31]

When water (H2O) is added to liquid isopropanol to form a solution, then polar isopropanol molecules are attracted to polar water molecules at the surface of the water. It forms a solution of rubbing alcohol.

<h3>Isopropanol and water in the solution</h3>

Isopropyl alcohol is water-soluble and forms hydrogen bonds with molecules of water (H2O).

When H2O is added to liquid isopropanol to form a solution, H2O spread in a uniform way in the solution.

These isopropanol molecules can surround H2O molecules, which are carried into the solution.

Learn more about isopropyl alcohol here:

brainly.com/question/799124

3 0

3 years ago