[H+] is ______

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.8

Lubov Fominskaja [6]

Complete Question

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.82 when exactly 13 mL of base had been added, you notice that the concentration of the unknown acid was 0.1 M. What is the pKa of your unknown acid?

Answer:

The pK_a value is $pK_a =7.82$

Explanation:

From the question we are told

The volume of base is $V_B = 26.mL = 0.0260L$

The pH of solution is $pH = 7.82$

The concentration of the acid is $C_A = 0.1M$

From the pH we can see that the titration is between a strong base and a weak acid

Let assume that the the volume of acid is $V_A = 18mL= 0.018L$

Generally the concentration of base

$C_B = \frac{C_AV_A}{C_B}$

Substituting value

$C_B = \frac{0.1 * 0.01800}{0.0260}$

$C_B= 0.0692M$

When 13mL of the base is added a buffer is formed

The chemical equation of the reaction is

$HA_{(aq)} + OH^-_{(aq)} --------> A^{+}_{(aq)} + H_2 O_{(l)}$

Now before the reaction the number of mole of base is

$No \ of \ moles[N_B] = C_B * V_B$

Substituting value

$N_B = 0.01300 * 0.0692$

$= 0.0009 \ moles$

Now before the reaction the number of mole of acid is

$No \ of \ moles = C_B * V_B$

Substituting value

$N_A = 0.01800 *0.1$

$= 0.001800 \ moles$

Now after the reaction the number of moles of base is zero i.e has been used up

this mathematically represented as

$N_B ' = N_B - N_B = 0$

The number of moles of acid is

$N_A ' = N_A - N_B$

$= 0.0009\ moles$

The pH of this reaction can be mathematically represented as

$pH = pK_a + log \frac{[base]}{[acid]}$

Substituting values

$7.82 = pK_a +log \frac{0.0009}{0.0009}$

$pK_a =7.82$

8 0

3 years ago

How to convert n butylbenzene to benzoic acid

Pavlova-9 [17]

Answer:

When an alkyl benzene is heated with strong oxidizing asgents like acidic or alkline KMnO4

or acidified K2Cr2O7

, etc. gives aromatic carboxyllic acid. The alkyl side chain gets oxidised to −COOH

group irrespective of the size of the chain.

Explanation:

4 0

3 years ago

Cu + 2AgNO3 →

netineya [11]

Answer: 292.54g of Ag

Explanation:

Cu + 2AgNO3 →Cu(NO3)2 + 2 Ag

mass conc. Of Ag = n x molar Mass

Mass conc. Of Ag = 2 x 108 = 216g

From the equation,

63.5g of Cu produced 216g of Ag

Therefore, 86g of Cu will produce Xg of Ag. i.e

Xg of Ag = (86 x 216)/63.5 = 292.54g

5 0

3 years ago

What experimental observations indicate a gas is being released?

joja [24]

Answer:

new substances formed, as evidenced by the color changes and bubbles. Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color chage, formation of a precipitate, formation of a gas, odor change, temperature change.

HOPE THIS HELPED!!!!!!!!!!!!!!XDDDDDDDDDD

3 0

3 years ago

Why are physical properties such as hardness or cleavage useful to geologists when identify minerals?

nevsk [136]

Answer:

Physical properties are controlled by the mineral's chemical composition and atomic structure, this combination is distinct in each mineral.

Explanation:

Hello,

Since the physical properties depend on the mineral's chemical composition and the atomic structure (molecular arrangement), we can distinguish different minerals by measuring out hardness, cleavage and other properties in order to analyze their behavior under several conditions and subsequently use them in a particular application.

Best regards.

5 0

3 years ago

[H+] is _______.