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
vova2212 [387]
3 years ago
6

Calculate the Ka of a 0.35M weak acid with a pH of 4.2.

Chemistry
1 answer:
Nadusha1986 [10]3 years ago
8 0

Answer:

Ka = 1.14x10⁻⁸

Explanation:

First we <u>calculate [H⁺] from the pH</u>:

  • pH = -log[H⁺]
  • [H⁺] = 10^{-pH}
  • [H⁺] = 6.31x10⁻⁵ M

For a monoprotic weak acid, the molar concentration of H⁺ of a solution can be expressed as:

  • [H⁺] = √(C*Ka)

Where C is the molar concentration of the weak acid solution.

  • 6.31x10⁻⁵ M = \sqrt{0.35M*Ka}
  • 1.14x10⁻⁸ = Ka
You might be interested in
Which solution has the higher boiling point?
dedylja [7]

NaCl has higher boiling point than C₂H₆O₂ in H₂O.

<h3>What is molality?</h3>
  • The number of moles of solute in a solution equal to 1 kg or 1000 g of solvent is referred to as its molality.
  • The definition of molarity, on the other hand, is based on a certain volume of solution.
  • Mol/kg is a typical molality measurement unit in chemistry.
<h3>Calculation of boiling point:</h3>

When the non-volatile solute is dissolved in a solvent, the boiling point rises along with the molality (concentration) of the solute.

Given,

Mass of  C₂H₆O₂ (solute) = 15.0 g

Mass of solvent (H₂O) = 0.50 kg

Molar mass of C₂H₆O₂ = 62 g/mol

Thus, the moles of solute = 15.0 g x 1.0 mol solute/62 g/mol

= 0.2419 mol

Therefore, molality(m) of C₂H₆O₂ (solute) = Amount of solute (mol)/ Mass of solvent

= 0.2419/0.50

= 0.4838 m

Similarly,

Given ,

Mass of  NaCl (solute) = 15 g

Mass of solvent (H₂O) = 0.50 kg

Molar mass of NaCl (solute) = 58.44 g/mol

Thus, the moles of NaCl (solute) = 15.0 g x 1.0 mol solute/58.44

= 0.2566 mol

Therefore, molality(m) of NaCl (solute) = Amount of solute (mol)/ Mass of solvent

= 0.2566 mol/0.50 kg  

= 0.51 m

Hence, the molality of NaCl (solute) is more than the molality of C₂H₆O₂(solute).

So, with an increase in the solute's concentration (molality), the boiling point rises.

Therefore, NaCl has higher boiling point than C₂H₆O₂ in H₂O.

Learn more about boiling point here:

brainly.com/question/24168079

#SPJ4

7 0
2 years ago
Nitrous oxide gas is a form of
zepelin [54]
Its a form of anaesthesia used by dentists 

hope that helsp 
6 0
3 years ago
Calculate the maximum KE and velocity of an electron from zinc by a 275nm photon
Dmitry [639]

Answer:

Kinetic energy: 6.024*10^{-20}

Velocity: 3.64*10^{5}

Explanation:

From the equations of the photo-electric effect,

We know:

hv=hv_0+K.E

Where,

1.h is the Planck's constant which is 6.626*10^{-34}

2.v,v_0 are the frequency of light emitted and threshold frequencies respectively.

3.K.E is the kinetic energy of the electrons emitted.

By fact, we come to know that the threshold frequency of Zn is 300nm

And also v=\frac{c}{d}

Where ,

1. c is the speed of light =3*10^8

2.d is the wavelength.

Thus,

\frac{hc}{d}=\frac{hc}{d_0}+K.E\\K.E=\frac{hc}{d}-\frac{hc}{d_0}\\K.E=hc*(\frac{1}{d}-\frac{1}{d_0})\\K.E=6.626*10^{-34}*3*10^8*(\frac{1}{275*10^{-9}}-\frac{1}{300*10^{-9}})\\K.E=6.024*10^{-20}kgm^2s^{-2}

Now to find velocity:

K.E=\frac{1}{2}mv^2\\v^2=1.324*10^{11}\\v=3.64*10^5

8 0
3 years ago
Calculate the number of moles when 3.00l of a gas at 814 mmhg and 25 °c?
Mariulka [41]
  • Volume=V=3L
  • Pressure=P=814mmHg
  • Temp=T=25°C

So

No of moles=n

\\ \rm\rightarrowtail PV=nRT

\\ \rm\rightarrowtail n=\dfrac{PV}{RT}

\\ \rm\rightarrowtail n=\dfrac{814(3)}{25R}

\\ \rm\rightarrowtail n=2442/25R

\\ \rm\rightarrowtail n=97.7Rmol

5 0
2 years ago
Identify the following reaction type using the chemical equation below*
OLEGan [10]

Answer:

its C. a combustion reaction

3 0
3 years ago
Other questions:
  • The compound methyl butanoate smells like apples. Its percent composition is 58.8% C, 9.9% H, and 31.4% O. What’s the empirical
    13·1 answer
  • 1 How is the density of a substance calculated? 
    12·1 answer
  • The rate at which a chemical reaction occurs cannot be changed. (True or False)
    15·1 answer
  • Select the compounds from the list below which are insoluble in water
    8·1 answer
  • From top to bottom in a group of elements, ionization energies tend to...
    7·1 answer
  • How can the existence of atoms help to explain the law of define proportions .
    15·1 answer
  • The plunger on a bicycle pump with a 400 mL volume cylinder is
    11·1 answer
  • In methane combustion, the following reaction pair is important: At 1500 K, the equilibrium constant Kp has a value of 0.003691
    12·1 answer
  • Someone please help i don’t have much time left
    12·1 answer
  • Riddle: What has to be broken before you can use it?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!