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san4es73 [151]
3 years ago
5

Groundwater in Pherric, New Mexico, initially contains 1.800 mg/L of iron as Fe3+. What must the pH be raised to in order to pre

cipitate all but 0.3 mg/L of the iron? The temperature of the solution is 25˚C.
Chemistry
1 answer:
xenn [34]3 years ago
4 0

Answer : The pH will be, 3.2

Explanation :

As we known that the value of solubility constant of ferric hydroxide at 25^oC is, 2.79\times 10^{-39}

Amount or solubility of iron consumed = (1.800 - 0.3) mg/L = 1.5 mg/L

The given solubility of iron convert from mg/L to mol/L.

1.5mg/L=\frac{1.5\times 10^{-3}g/L}{56g/mol}=2.7\times 10^{-7}mol/L

The chemical reaction will be:

Fe(OH)_3\rightarrow Fe^{3+}+3OH^-

The expression of solubility constant will be:

K_{sp}=[Fe^{3+}]\times [3OH^-]^3

Now put all the given values in this expression, we get the concentration of hydroxide ion.

2.79\times 10^{-39}=(2.7\times 10^{-7})\times [3OH^-]^3

[OH^-]=1.5\times 10^{-11}M

Now we have to calculate the pOH.

pOH=-\log [OH^-]

pOH=-\log (1.5\times 10^{-11})

pOH=10.8

Now we have to calculate the pH.

pH+pOH=14\\\\pH=14-pOH\\\\pH=14-10.8\\\\pH=3.2

Therefore, the pH will be, 3.2

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ycow [4]

Answer:

D

Explanation:

This explains how two noble gases molecules can have an attractive force between them.

This force is called as van dar Waals forces.

It plays a fundamental role in fields in as diverse as supramolecular chemistry structural biology .

If no other forces are present, the point at which the force becomes repulsive rather than attractive as two atoms near one another is called the van der Waals contact distance. This results from the electron clouds of two atoms unfavorably coming into contact.[1] It can be shown that van der Waals forces are of the same origin as the Casimir effect, arising from quantum interactions with the zero-point field.[2] The resulting van der Waals forces can be attractive or repulsive.[3] It is also sometimes used loosely as a synonym for the totality of intermolecular forces.[4] The term includes the force between permanent dipoles (Keesom force), the force between a permanent dipole and a corresponding induced dipole (Debye force), and the force between instantaneously induced dipoles

6 0
2 years ago
How do you convert from grabs to moles of a substance
Lorico [155]

The correct question is as follows:

How do you convert from grams to moles of a substance

1. Divide by the molar mass

2. Subtract the molar mass

3. Add the molar mass

4. Multiple by the molar mass

Answer: In order to convert from grams to moles of a substance divide by the molar mass.

Explanation:

The number of moles of a substance is the mass of substance in grams divided by its molar mass.

The formula to calculate moles is as follows.

Moles = \frac{mass}{molar mass}

This means that grams are converted to moles when grams is divided by molar mass.

Thus, we can conclude that in order to convert from grams to moles of a substance divide by the molar mass.

8 0
3 years ago
A certain process has ΔH° > 0, ΔS° < 0, and ΔG° > 0. The values of ΔH° and ΔS° do not depend on the temperature. Which
tino4ka555 [31]

Answer: It is non-spontaneous at all T.

Explanation:

According to Gibb's equation:

\Delta G=\Delta H-T\Delta S

\Delta G = Gibbs free energy = +ve

\Delta H = enthalpy change  = +ve

\Delta S = entropy change  = -ve

T = temperature in Kelvin

\Delta G= +ve, reaction is non spontaneous

\Delta G= -ve, reaction is spontaneous

\Delta G= 0, reaction is in equilibrium

Putting in the values:

\Delta G=(+ve)-T(-ve)

\Delta G=(+ve)(+ve)=+ve  

Reaction is non spontaneous at all temperatures.

4 0
3 years ago
I need help plez! Thank you!
vladimir2022 [97]
The answer should be E,C,F,B,A,D in that order.
6 0
3 years ago
What is the mass in grams of 5.2 moles of NaCl?<br> 303.89 g<br> 0.09 g<br> 119.6 g<br> 1828
Vitek1552 [10]

Explanation:

mole=mass/molar mass

mass= mole×molar mass

m= 5.2×( 23+35.5)

m= 5.2×58.5

m= 304.2g

6 0
3 years ago
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