Equilateral triangle What’s the answer

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

15 grams of sodium reacts with a certain amount of chlorine to yield 37 grams of sodium chloride, as shown below.

ale4655 [162]

Answer: 22g of chlorine would be needed to carry out this synthesis reaction

Explanation:

A synthesis reaction is one in which two or more than two elements combine together to forma single product.

$Na+Cl\rightarrow NaCl$

The atoms present in the reactants are found on the product side. According to the law of conservation of mass, the number of atoms on both sides of the arrow must be same as the total mass must be conserved.

15 grams of sodium reacts with 22 grams of chlorine to yield 37 grams of sodium chloride. Thus 22g of chlorine would be needed to carry out this synthesis reaction.

4 0

3 years ago

Which of the following statements provides the BEST explanation for the many chemical similarities between two elements in a Mai

rjkz [21]

Answer:

(b) Both have the same number of valence electrons.

Step-by-step explanation:

We find the most striking chemical similarities between two Main Group elements when they are in the same Group of the Periodic Table.

Elements in the same Group have the same number of valence electrons.

(a) is wrong, because elements in the same group have different masses.

(c) is wrong, because atoms with the same number of protons belong to the same element.

(d) is wrong, because elements in the same Group must be in . different Periods.

7 0

3 years ago

3. An object has a mass of 20.0 grams and a volume of 5.0 cubic centimeters. Give the density

Savatey [412]

density= mass/ volume

d= 20/5

d= 4 g/cm^3

4 0

3 years ago

Read 2 more answers

What principle chemistry

NNADVOKAT [17]

Is this a question ?

8 0

3 years ago