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2 years ago

Given the statements:

Chemistry

2 answers:

Andre45 [30]2 years ago

7 0

Answer:

The purpose of salt bridge is

b. the salt bridge prevents the direct mixing of one half-cell solution with the other.

d.the salt bridge allows ions to migrate from one half-cell to the other.

Explanation:

Salt bridge is a structure which is placed as a bridge between two half cells of a voltaic cell. It contains a gel like agar agar and some salt like KCl.

If we do not use salt bridge, the cell will stop working after some time due to accumulation of positive ions around anode and negative ions around cathode.

So salt bridge maintains electro-neutrality (by reaction of positive ions of salt bride salt with negative ions of anodic compartment and by reaction of neagative ions of salt bride salt with positive ions of cathodic compartment).

It prevents mixing of two half cell solution but allows ions to migrate from one half-cell to the other.

olga nikolaevna [1]2 years ago

3 0

C. The salt bridge maintains the flows of ions and allows electrons to move from the anode to the cathode.

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A student obtained a clean flask. She weighed the flask and stopper on an analytical balance and found the total mass to be 34.2

DanielleElmas [232]

Answer:

25.99mL is the volume internal volume of the flask

Explanation:

<em>To complete the question:</em>

<em>The temperature of the water was measured to be 21ºC. Use this data to find the internal volume of the stoppered flask</em>

<em />

The flask was filled with water, that means the internal volume of the flask is equal to the volume that the water occupies.

To find the volume of the water you need to find the mass and by the use of density of water at 21ºC (0.997992g/mL), you can find the volume of the flask, thus:

Mass water = Mass filled flask - Mass of clean flask

Mass water = 60.167g - 34.232g

Mass water = 25.935g of water.

To convert this mass to volume:

25.935g × (1mL / 0.997992g) =

<h3>25.99mL is the volume internal volume of the flask</h3>

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2 years ago

Both the esophagus and the small intestine are involved in the digestion of food. The esophagus squeezes food into the stomach b

UkoKoshka [18]

Answer:

The answer is: A

Explanation:

The wave-like contractions are to be considered a physical change as they do not take part in the breaking-down of the food. The peptidase is a chemical change because it is used to chemically break down the food to retrieve nutrients and such.

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2 years ago

Water at 4.4°C is to flow through a horizontal, commercial steel pipe having a length of 305 m at the rate of 150 gal/min. If a

Pavel [41]

Answer:

d = 70.5 mm

Explanation:

given,

length of pipe = 305 m

discharge rate = 150 gal/min

pipe diameter = ?

1 gal/min = 6.30902 × 10⁻⁵ m³/s

150 gal/min = 150 × 6.30902 × 10⁻⁵ m³/s

= 9.46 × 10⁻³ m³/s

$h = \dfrac{flv^2}{2gd}$

Q = A V

$h = \dfrac{fl(\dfrac{Q}{A})^2}{2gd}$

$h = \dfrac{fl(\dfrac{Q}{\dfrac{\pi}{4}d^2})^2}{2gd}$

$h= \dfrac{8flQ^2}{\pi^2gd^5}$

f = 0.048 from moody chart using P/D = 0.00015

$\dfrac{1}{d^5}= \dfrac{6.1\times \pi^2\times 9.8}{8\times 0.048\times 305\times 0.00946^2}$

d = 70.5 mm

Diameter of the pipe is equal to 70.5 mm

7 0

2 years ago

6. Under standard-state conditions, what spontaneous reaction will occur in aqueous solution among the ions Ce4+, Ce3+, Fe3+, an

xz_007 [3.2K]

Answer:

ΔG° = -80.9 KJ

Assuming this reaction takes place at room temperature (25 °C):

K= $1.53x10^{14}$

Explanation:

1) Reduction potentials

First of all one should look up the reduction potentials for the species envolved:

$Ce^{4+} + e$ → $Ce^{3+}$ E°red=1.61V

$Fe^{3+} + e$ → $Fe^{2+}$ E°red=0.771V

2) Redox pair

Knowing their reduction pontentials one can determine a redox pair: one species must oxidate while the other is reducing. <u>Remember: the table gives us the reduction potential, so if we want to know the oxidation potential all that has to be done is reverce the equation and change the potencial signal (multiply to -1).</u>

1) $Ce^{4+}$ reduces while $Fe^{2+}$ oxidates

(oxidation) $Fe^{2+}$ → $Fe^{3+} + e$ E°oxi=-0.771V

(reduction) $Ce^{4+} + e$ → $Ce^{3+}$ E°red=1.61V

(overall equation) $Fe^{2+}+Ce^{4+}$ → $Ce^{3+}+Fe^{3+}$ E°=Ereduction + Eoxidation= 1.61 v+(-0.771 v) = 0.839v

The cell potential can also be calculated as the cathode potencial minus the anode potential:

E° = E cathode - E anode =1.61 v - 0.771 v=0.839 v

3) Gibbs free energy and Equilibrium constant

ΔG°=-nFE°, where 'n' is the number of electrons involved in the redox equation, in this case n is 1. 'F' is the Faraday constant, whtch is 96500 C. E° is the standard cell potencial.

ΔG°=-nFE°=-1*96500*0.839

ΔG° = - 80963 J = -80.9 KJ

The Nerst equation gives us the relation of chemical equilibrium and Electric potential.

E=E°- $\frac{RT}{nF} Ln Q$

Where 'R' is the molar gas constant (8.314 J/mol)

It's known that in the equilibrium E=0, so the Nerst equation, at equilibrium, becomes:

E°= $\frac{RT}{nF} Ln K$

Isolating for 'K' gives:

$K=e^{\frac{nFE^{o} }{RT} }$

This shows that 'K' is a fuction of temperature. Assuming this reaction takes place at room temperature (25 °C):

K= $1.53x10^{14}$

6 0

2 years ago

There is water on the pan of the scale as you measure the mass of an object. If you were to ignore the water, what would be the

mihalych1998 [28]

Remember that density refers to the "mass per unit volume" of an object.

So, if an object had a mass of 100 grams and a volume of 100 milliliters, the density would be 100 grams / 100 ml.

In the question, water on the surface of the scale would add weight, so the mass of the object that you're weighing would appear to be heavier than it really is. If that happens, you'll incorrectly assume that the density is GREATER than it really is

As an example, suppose that there was 5 ml of water on the surface of the scale. Water has a density of 1 gram per milliliter (1 g/ml) so the water would add 5 grams to the object's weight. If we use the example above, the mass of the object would seem to be 105 grams, rather than 100 grams. So, you would calculate:

density = mass / volume
density = 105 grams / 100 ml
density = 1.05 g/ml

The effect on density would be that it would erroneously appear to be greater

Hope this helps!

Good luck

6 0

2 years ago