1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
irakobra [83]
3 years ago
13

Consider the titration of 1L of 0.36 M NH3 (Kb=1.8x10−5) with 0.74 M HCl. What is the pH at the equivalence point of the titrati

on? A) 4.69 B) 4.85 C) 4.94 D) 9.06 E) 9.31
Chemistry
1 answer:
worty [1.4K]3 years ago
7 0

Answer:

C

Explanation:

The question asks to calculate the pH at equivalence point of the titration between ammonia and hydrochloric acid

Firstly, we write the equation of reaction between ammonia and hydrochloric acid.

NH3(aq)+HCl(aq)→NH4Cl(aq)

Ionically:

HCl + NH3 ---> NH4  +  Cl-

Firstly, we calculate the number of moles of  the ammonia  as follows:

from c = n/v and thus, n = cv = 0.36 × 1 = 0.36 moles

At the equivalence point, there is equal number of moles of ammonia and HCl.

Hence, volume of HCl = number of moles/molarity of HCl = 0.36/0.74 = 0.486L

Hence, the total volume of solution will be 1 + 0.486 = 1.486L

Now, we calculate the concentration of the ammonium ions = 0.36/1.486 = 0.242M

An ICE TABLE IS USED TO FIND THE CONCENTRATION OF THE HYDROXONIUM ION(H3O+). ICE STANDS FOR INITIAL, CHANGE AND EQUILIBRIUM.

                 NH4+      H2O     ⇄  NH3        H3O+

I                0.242                           0             0

C                 -X                              +x              +X

E             0.242-X                          X              X

Since the question provides us with the base dissociation constant value K b, we can calculate the acid dissociation constant value Ka

To find this, we use the mathematical equation below

K a ⋅ K b    = K w

 

, where  K w- the self-ionization constant of water, equal to  

10 ^-14  at room temperature

This means that you have

K a = K w.K b   = 10 ^− 14 /1.8 * 10^-5 =  5.56 * 10^-10

Ka = [NH3][H3O+]/[NH4+]

= x * x/(0.242-x)

Since the value of Ka is small, we can say that 0.242-x ≈  0.242

Hence, K a = x^2/0.242 = 5.56 * 10^-10

x^2 = 0.242 * 5.56 * 10^-10 = 1.35 * 10^-10

x = 0.00001161895

[H3O+] = 0.00001161895

pH = -log[H3O+]

pH = -log[0.00001161895 ] = 4.94

You might be interested in
The volume (in L) that would be occupied by 5.00 mols of 02 at STP is
crimeas [40]

Answer : The volume of oxygen at STP is 112.0665 L

Solution : Given,

The number of moles of O_2 = 5 moles

At STP, the temperature is 273 K and pressure is 1 atm.

Using ideal gas law equation :

PV=nRT

where,

P = pressure of gas

V = volume of gas

n = the number of moles

T = temperature of gas

R = gas constant = 0.0821 L atm/mole K   (Given)

By rearranging the above ideal gas law equation, we get

V=\frac{nRT}{P}

Now put all the given values in this expression, we get the value of volume.

V=\frac{(5moles)\times (0.0821Latm/moleK)\times (273K)}{1atm}=112.0665L

Therefore, the volume of oxygen at STP is 112.0665 L

3 0
3 years ago
Organisms do not adapt as a result of competition for resources. Please select the best answer from the choices provided T F
Ymorist [56]
The answer is FALSE.
Hope this helps.
6 0
3 years ago
Read 2 more answers
What is the correct equilibrium constant
Elza [17]

Answer:[co2][CF4]

[COF2]^2

Explanation:

4 0
3 years ago
Read 2 more answers
A is a discussion characterized by procedures of argumentation.
galina1969 [7]
Debate is the correct answer
NOT counterclaim, rebuttal or resolution

4 0
3 years ago
Read 2 more answers
PLEASE HELP ME PLEASE PLEASE PLEASE
TEA [102]

Answer:

sorry

Explanation:

3 0
3 years ago
Other questions:
  • When a gas is cooled at constant pressure, what happens to its molecules and volume?
    7·1 answer
  • What is the difference between a cesium atom (Cs) and a cesium ion (Cs+1)?
    13·1 answer
  • Approximately _____ elements occur naturally on earth.
    13·2 answers
  • Iron forms a series of compounds of the type Fex(CO)y. In air, they are oxidized to Fe2O3and CO2gas. After heating a 0.142 g sam
    7·1 answer
  • PLEASE HELPPP MEEEE
    12·2 answers
  • Write or show a complete formation of the following ionic compounds <br>a)sodium oxide (Na2O)​
    10·1 answer
  • 6q+4-q+5 <br><br> please help
    9·1 answer
  • Consider a mixture of two gases, A and B, confined in a closed vessel. A quantity of a third gas, C, is added to the same vessel
    7·1 answer
  • How can you tell if a chemical equation is balanced
    8·1 answer
  • When iron reacts with oxygen, it forms iron oxide, or rust.
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!