Can someone please help me in physical science

A total charge of 9.0 mC passes through a cross-sectional area of a nichrome wire in 3.6s. The number of electrons passing throu

Shtirlitz [24]

Answer:

n = 1.56 x 10¹⁷ electrons

Explanation:

First of all, we will calculate the current passing through wire:

$I = \frac{q}{t}$

where,

I = current = ?

q = charge = 9 mC = 0.009 C

t = time = 3.6 s

Therefore,

$I = \frac{0.009\ C}{3.6\ s}\\\\I = 0.0025\ A = 2.5\ mA$

Now, for the same current in 10 s time the charge will be:

q = It = (0.0025 A)(10 s)

q = 0.025 C

Now, the number of electrons can be given as:

$q = ne\\\\n = \frac{q}{e}\\\\$

where,

n = no. of electrons = ?

q = charge = 0.025 C

e = charge on single electron = 1.6 x 10⁻¹⁹ C

Therefore,

$n = \frac{0.025\ C}{1.6\ x\ 10^{-19}\ C}$

<u>n = 1.56 x 10¹⁷ electrons</u>

8 0

3 years ago

A galvanic cell based on these half-reactions is set up under standard conditions where each solutions is 1.00 L and each electr

Marat540 [252]

Complete Question

$Fe^{2+} + 2e^-----> Fe \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ E^0_{red} = - 0.441 V$

$Cd^{2+} + 2e^- -----> Cd \ \ \ \ \ \ \ \ \ \ \ \ \ \ E^0_{red} = -0.403V$

A galvanic cell based on these half-reactions is set up under standard conditions where each solutions is 1.00 L and each electrode weighs exactly 100.0 g. How much will the Cd electrode weigh when the non-standard potential of the cell is 0.03305 V?

Answer:

The mass is M= 117.37g

Explanation:

The overall reaction is as follows

$Cd^{2+} + Fe Fe^{2+} + Cd$

The reaction is this way because the potential of $Cd^{2+} \ reducing \ to \ Cd$ is higher than the potential of $Fe^{2+} \ reducing \ to \ Fe$ so the the Fe would be oxidized and $Cd^{2+}$ would be reduced

At equilibrium the rate constant of the reaction is

$Q = \frac{concentration \ of \ product }{concentration \ of reactant }$

$= \frac{[Fe^{2+}[Cd]]}{[Cd^{2+}][Fe]}$

The Voltage of the cell $E_{cell} = E_{Cd^{2+}/Cd } + E_{Fe^{2+} /Fe}$

Substituting the given values into the equation

$E_{cell} = -0.403 -(-0.441)$

$= 0.038V$

The voltage of the cell at any point can be calculated using the equation

$E = E_{cell} - \frac{0.059}{n_e} Q$

Where $n_e \ is \ the \ number\ of\ electron$

Substituting for Q

$E = E_{cell} - \frac{0.059}{n_e} \frac{[Fe^{2+}[Cd]]}{[Cd^{2+}][Fe]}$

When E = 0.03305 V

$E = E_{cell} - \frac{0.59}{n_e} \frac{Fe^{2+}}{Cd^{2+}}$

Since we are considering the Cd electrode the equation becomes

$E= E_{cell} - \frac{0.059}{n_e} [\frac{1}{Cd^{2+}} ]$

Substituting values and making [ $Cd^{2+}$ ] the subject

$[Cd^{2+}] =\frac{1}{e^{[\frac{0.03305- 0.038}{\frac{0.059 }{2} }] }}$

$= 0.8455M$

Given from the question that the volume is 1 Liter

The number of mole = concentration * volume

= 0.8455 * 1

= 0.8455 moles

At the standard state the concentration of $Cd^{2+}$ is =1 mole /L

Hence the amount deposited on the Cd electrode would be

= Original amount - The calculated amount

= 1 - 0.8455

= 0.1545 moles

The mass deposited is mathematically represented as

$mass = mole * molar \ mass$

The Molar mass of Cd $= 112.41 g/mol$

Mass $= 0.1545 *112.41$

$= 17.37g$

Hence the total mass of the electrode is = standard mass + calculated mass

M= 100+ 17.37

M= 117.37g

6 0

3 years ago

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When two substance mixed together what does not indicate that a chemical reaction has

nevsk [136]

Answer:

When two substances are mixed together, a color change is observed. This observation is not enough evidence that there is a chemical reaction happening because color changes are not indicators of chemical reaction:

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Meiosis produce

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D)four cells that each have half as many chromosomes as the parent cell

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4 years ago

A beam of light traveling in air strikes a glass slab at an angle of incidence less than 90°. After entering the glass slab, wha

omeli [17]

Answer:

It gets refracted.

Explanation:

When light beam travels through different mediums they refract i.e. they change their direction. Here the angle of incidence is less than 90°. After entering the glass slab the light beam will move towards the normal (a line drawn perpendicular to the interface of the two mediums). Thus the angle of refraction will be even lesser than angle of incidence.

8 0

3 years ago