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2 years ago

Why do some salts dissolve spontaneously even though the process is endothermic overall?

1 answer:

3 0

The process of ionic compounds like salts dissolving into an aqueous or other kind of polar solvent is independent of the fact of whether or not the process is endo or exothermic. The amount of heat energy needed is very very small.

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(pls help !!) question is in image

Anastaziya [24]

Answer:

the second option is correct

Explanation:

maybe I think b is correct

6 0

1 year ago

Which machine is the least simple? a bike a screw an inclined plane a lever

Ivenika [448]

Answer: A bike

A bike is composed of various simple machines. It has a wheel and axle as one component, and it also has screws to hold the various parts together, along with levers and pulleys that are connected to the pedals. So all of these simple machine concepts work together to help transport the rider from point A to point B.

The other answer choices of screw, inclined plane, and lever, are fairly simple machines that don't have many things going on at once compared to a bike.

4 0

2 years ago

Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an el

givi [52]

Answer: The amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

Explanation:

We are given:

Moles of electron = 1 mole

According to mole concept:

1 mole of an atom contains $6.022\times 10^{23}$ number of particles.

We know that:

Charge on 1 electron = $1.6\times 10^{-19}C$

Charge on 1 mole of electrons = $1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C$

$Cu^{2+}+2e^-\rightarrow Cu$

$2\times 96500=193000C$ is passed to deposit = 1 mole of copper

63.5 g of copper is deposited by = 193000 C

$14\times 1000g=14000g$ of copper is deposited by = $\frac{193000}{63.5}\times 14000=42551181 C$

To calculate the time required, we use the equation:

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

where,

I = current passed = 40.0 A

q = total charge = 42551181 C

t = time required = ?

Putting values in above equation, we get:

$40.0=\frac{42551181 C}{t}\\\\t=1063779sec$

Converting this into hours, we use the conversion factor:

1 hr = 3600 seconds

So, $1063779s\times \frac{1hr}{3600s}=295hr$

Hence, the amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

3 0

2 years ago

Please give me the reasons of the solution!

irinina [24]

1. The answer is option E, that is None of the above is correct.

As a polymer becomes more crystalline,

its melting point doesn't decreases, its density doesn't decreases, its stiffness doesn't decreases and its yield stress doesn't decreases.

2. The answer is option B, that is the molecules are arranged in sheets, with their long axes parallel and their ends aligned as well.

In the smectic A liquid-crystalline phase, molecules are arranged in sheets, with their long axes parallel and their ends aligned as well.

3. For a substitutional alloy to form, the two metals combined must have similar atomic radii and chemical bonding properties.

6 0

2 years ago

Can someone tell me how to differentiate if a given salt is acidic, basic, or neutral?

satela [25.4K]

$\bold{\huge{\underline{ Solution }}}$

<h3>Basic Characteristic of acids </h3>

Acids are sour in taste
Acid turns blue litmus paper or solution into red litmus paper or solution
Acids are good conductor of electricity because it dissociate into cation in aqueous solution
Acids classified into edible acids and non edible acids. Non edible acids are very hazardous
Generally, All acids are soluble in water
Acids have PH smaller than 7

Arrhenius definition of acids :-

According to Arrehinus,

Acids are those substances which when dissolve in water given H positive ions . Then, this hydrogen ions combine with water to form H30 + ions

Second definition of Acids was given by Bonsted Lowry :-

According to Bonsted Lowry

Acids are the proton donors that is when acids dissociate into water gives hydrogen ions that is H+ ions

3rd definition was given by Lewis 

According to Lewis

Acids are those substances which have the ability to accept a pair of electrons .

Example of Acids

HNO3 :- Nitric acid
H2SO4 :- Sulfuric acid
HCl :- Hydrochloric acid

<h3>Basic characterists of bases </h3>

Bases are bitter in taste
Bases turns red litmus paper into blue litmus paper or solution
Bases are also good conductor of electricity because on dissociation it produces anion in aqueous solution
Bases are also good conductor of electricity
When bases are soluble in water then they are known as alkaline base
Bases have PH greater than 7

Arrehinus definition of bases :-

According to Arrehinus ,

Bases are those substances which when dissolve in water produce OH negative ions that is hydroxide ions

Bonsted Lowry definition 

According to Bonsted Lowry

Bases are the proton donors as they produce OH negative ions in dissociation in aqueous solution

Lewis definition 

According to Lewis

Acids are those substances which have the ability to lose electrons that is they are electron donors.

Example of bases

Ca(OH)2 :- Calcium hydroxide
NaOH :- Sodium hydroxide
KOH :- Potassium hydroxide

[ Note :- There are so many Lewis acids and bases but they are not Arrhenius or Lowry acids or bases ]

<h3>Basic characteristic of salt </h3>

Salts are the ionic compounds which are composed of acids and bases that cation and anion
Salts are generally found in oceans and seas in the forms of crystals
As they are composed of acids and bases so they are neutral in nature but the salt of strong acid or weak base is acidic in nature or vice versa
Salts are also good conductor of electricity as they form ionic bond
Generally, All salts are soluble in water.
The PH of common Salt is 7

Example of salts

NH4Cl :- Ammonium chloride
CuSO4 :- Copper sulphate
NaCl :- Sodium chloride

6 0

1 year ago