Q.15. Which of the following chemical reactions represents an acid-base reaction? a) HBr + NaOH → NaBr + H2O

the ph of a solution of HCl in water is found to be 2.50. what volume of water would you add to 1.00L of this solution to raise

morpeh [17]

Answer:

To raise the pH of the solution to 3.10 we have to add 2.34 L of water.

Explanation:

Given that the pH of the solution of HCl in water is 2.5. Here the solution’s pH is changing from 2.5 to 3.10 which means the acidic nature of the solution is decreasing here on dilution. $[H^+]$ ions contribute to a solution’s acidic nature and $[OH^-]$ contribute to a solution’s basic nature.

The equation connecting the concentration of $[H^+]$ and pH of a solution is pH= $-log[H^+]$

 $[H^+]= 10^(^-^p^H^)$ $[H^+]= 10^(^-^2^.^5^)=0.00316$ 

When the pH is $3.1 [H^+ ]= 10^(^-^3^.^1^)=0.000794$ 

On dilution the concentration of a solution decreases and volume increases.

 $M_1 V_1 = M_2 V_2$ 

 $0.00316 \times 1 = 0.000794 \times V_2$ 

 $V_2 = \frac{(0.00316 \times 1)}{0.000794} =3.24$ 

Volume of water to be added $=3.24-1$ 

 $=2.24L$ 

6 0

3 years ago

Equal volumes of two solutions, one containing a strong acid at pH 2 and the other containing a strong base at pH 12, are mixed.

mash [69]

Answer:

7

Explanation:

Assume we have 1 L of each solution.

Solution 1

$\text{[H$^{+}$]}= 10^\text{-pH} \text{ mol/L} = 10^{\text{-2}} \text{ mol/L}\\ \text{ moles of H}^{+} = \text{ 1 L solution} \times \dfrac{10^{-2}\text{ mol H}^{+}}{\text{1 L solution}} = 10^{-2}\text{ mol H}^{+}$

Solution 2

pH = 12

pOH = 14.00 - pOH = 14.00 - 12 = 2.0

$\text{[OH$^{-}$]}= 10^\text{-pOH} \text{ mol/L} = 10^{\text{-2}} \text{ mol/L}\\ \text{ moles of OH}^{-} = \text{ 1 L solution} \times \dfrac{10^{-2}\text{ mol OH}^{-}}{\text{1 L solution}} = 10^{-2}\text{ mol OH}^{-}$

3. pH after mixing

H⁺ + OH⁻ ⟶ H₂O

I/mol: 10⁻² 10⁻²

C/mol: -10⁻² -10⁻²

E/mol: 0 0

The H⁺ and OH⁻ have neutralized each other. The pH will be that of pure water.

pH = 7

8 0

4 years ago

If you cut an apple into slices and leave them in the open air, they will slowly turn brown. What kind of chemical change is thi

cupoosta [38]

Answer:

Due to oxidation process apple gets brown color.

Explanation:

When we cut the apple it turn brown in color because of the oxidation process. The peel of apple protect it from the oxidation. When the apple is peel off the oxygen and water molecules in air react with it and oxidation take place. The oxidation process is very efficient in ambient temperature.

For example, if the peal off apple is placed into the refrigerator it take a time to got oxidize and turn brown, but if it is placed in room temperature it quickly turn brown.

when oxygen is react with peel off apple , it trigger the polyphenol oxidase enzyme to oxidize the phenolic compound and quinones are formed which then react with amino acids and produced brown color.

3 0

3 years ago

Water is made of two [Blank] atoms and one [Blank] atom. (please fill in the blanks)

natima [27]

Two [hydrogen] atoms and one [oxygen] atom

5 0

3 years ago

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Which statements are true? The oxidation number for Cu(s) is +2. An oxidizing agent gains electrons. Na+ is formed from the redu

just olya [345]

Answer: The correct statements are:

An oxidizing agent gains electrons and $Zn^{2+}$ is formed from the oxidation of Zn(s).

Explanation:

For the given options:

Statement 1: The oxidation number for Cu(s) is +2

Copper is the 29th element of the periodic table having electronic configuration of $[Ar]3d^{10}4s^1$

This element can show +1 or +2 oxidation states. Thus, this statement is false.

Statement 2: An oxidizing agent gains electrons.

Oxidizing agents are defined as the agents which oxidize other substance and itself gets reduced. These agents undergoes reduction reactions and reduction reaction is the reaction in which an atom gains electrons.

Thus, this statement is True.

Statement 3: $Na^+$ is formed from the reduction of Na(s)

Oxidation reaction is defined as the reaction in which an atom looses its electrons. Here, oxidation state of the atom increases.

$X\rightarrow X^{n+}+ne^-$

Sodium is the 11th element and it will loose electrons to form sodium ion.

$Na\rightarrow Na^++e^-$

Hence, this statement is false.

Statement 4: The oxidation number for Hg(l) is 0.

Mercury is the 80th element of the periodic tale having electronic configuration of $[Xe]4f^{14}5d^{10}6s^2$

This element can show +1 or +2 oxidation states. Thus, this statement is false.

Statement 5: A reducing agent gains electrons.

Reducing agents are defined as the agents which reduces the other substance and itself gets oxidized. These agents undergoes oxidation reactions and oxidation reaction is defined as the reaction in which an atom looses its electrons.

Thus, this statement is false.

Statement 6: $Zn^{2+}$ is formed from the oxidation of Zn(s)

Oxidation reaction is defined as the reaction in which an atom looses its electrons. Here, oxidation state of the atom increases.

$X\rightarrow X^{n+}+ne^-$

Zinc is the 30th element and it will loose electrons to form zinc ion.

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

Thus, this statement is True.

Hence, the correct statements are:

An oxidizing agent gains electrons and $Zn^{2+}$ is formed from the oxidation of Zn(s).

4 0

3 years ago

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