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
mezya [45]
3 years ago
13

Use the ideal gas law to calculate the concentrations of nitrogen and oxygen present in air at a pressure of 1.0 atm and a tempe

rature of 298 K. Assume that nitrogen comprises 78% of air by volume and that oxygen comprises 21%.
Chemistry
1 answer:
zhannawk [14.2K]3 years ago
7 0

Answer:

The concentration of nitrogen per liter of air is 3.189 × 10⁻² moles

while the concentration of oxygen per liter of air is 8.59 × 10⁻³ moles

Explanation:

From Dalton's law of partial pressure, we have the pressure of the air is due to the partial pressures of the constituent gases

Therefore from the ideal gas law we have

PV = nRT, or P = nRT/V which for nitrogen is with volume = 78 % of the total volume giving us

Pressure of nitrogen = nRT/(0.78V) and oxygen gives

nRT/(0.21V) while the remaining contituent 1 % is

nRT/(0.01V)

Therefore we have nRT/(0.78V)  + nRT/(0.21V) + nRT/(0.01V) = Ptotal

however by Avogadro's law, equal volume of all gases at the same temperature and pressure contain equal number of molecules

and the partial pressure of a gas =mole fraction × total pressure

From which we have the mole fraction of nitrogen given as

nRT/(0.78V)  + nRT/(0.21V) + nRT/(0.01V) = nRT/V

cancelling like terms gives

n(nitrogen)/0.78 +n(oxygen)/0.21 +n(others)/0.01 =n/1

therefore the mole fraction of nitrogen = 0.78

and the mole fraction of oxygen = 0.21

or n = PV/RT = 1 * 0.78/(0.082057* 298) = 3.189 × 10⁻² moles per liter

Also we have for oxygen =1*0.21/(0.082057* 298) = 8.59 × 10⁻³ moles per liter

You might be interested in
Calculate the wavelength of light emitted when each of the following transitions occur in the hydrogen atom. What type of electr
Alecsey [184]

Answer:

The wavelength of the emitted photon will be approximately 655 nm, which corresponds to the visible spectrum.

Explanation:

In order to answer this question, we need to recall Bohr's formula for the energy of each of the orbitals in the hydrogen atom:

E_{n} = -\frac{m_{e}e^{4}}{2(4\pi\epsilon_{0})^2\hbar^{2}}\frac{1}{n^2} = E_{1}\frac{1}{n^{2}}, where:

[tex]m_{e}[tex] = electron mass

e = electron charge

[tex]\epsilon_{0}[tex] = vacuum permittivity

[tex]\hbar[tex] = Planck's constant over 2pi

n = quantum number

[tex]E_{1}[tex] = hydrogen's ground state = -13.6 eV

Therefore, the energy of the emitted photon is given by the difference of the energy in the 3d orbital minus the energy in the 2nd orbital:

[tex]E_{3} - E_{2} = -13.6 eV(\frac{1}{3^{2}} - \frac{1}{2^{2}})=1.89 eV[tex]

Now, knowing the energy of the photon, we can calculate its wavelength using the equation:

[tex]E = \frac{hc}{\lambda}[tex], where:

E = Photon's energy

h = Planck's constant

c = speed of light in vacuum

[tex]\lambda[tex] = wavelength

Solving for [tex]\lambda[tex] and substituting the required values:

[tex]\lambda = \frac{hc}{E} = \frac{1.239 eV\mu m}{1.89 eV}=0.655\mu m = 655 nm[tex], which correspond to the visible spectrum (The visible spectrum includes wavelengths between 400 nm and 750 nm).

5 0
3 years ago
100.00 mL of 0.15 M nitrous acid (HNO2) are titrated with a 0.15 M NaOH solution. (a) Calculate the pH for the initial solution.
wolverine [178]

Answer:

a. pH = 2.04

b. pH = 3.85

c. pH = 8.06

d. pH = 11.56

Explanation:

The nitrous acid is a weak acid (Ka = 5.6x10⁻⁴) that reacts with NaOH as follows:

HNO₂ + NaOH → NaNO₂(aq) + H₂O(l)

a. At the beginning there is just a solution of 0.12M HNO₂. As Ka is:

Ka = [H⁺] [NO₂⁻] / [HNO₂]

Where [H⁺] and [NO₂⁻] ions comes from the same equilibrium ([H⁺] = [NO₂⁻] = X):

5.6x10⁻⁴ = X² / 0.15M

8.4x10⁻⁵ = X²

X = [H⁺] = 9.165x10⁻³M

As pH = -log [H⁺]

<h3>pH = 2.04</h3><h3 />

b. At this point we have HNO₂ and NaNO₂ (The weak acid and the conjugate base), a buffer. The pH of a buffer is obtained using H-H equation:

pH = pKa + log [NaNO₂] / [HNO₂]

<em>Where pH is the pH of the buffer,</em>

<em>pKa is -log Ka = 3.25</em>

<em>And [NaNO₂] [HNO₂] could be taken as the moles of each compound.</em>

<em />

The initial moles of HNO₂ are:

0.100L * (0.15mol / L) = 0.015moles

The moles of base added are:

0.0800L * (0.15mol / L) = 0.012moles

The moles of base added = Moles of NaNO₂ produced = 0.012moles.

And the moles of HNO₂ that remains are:

0.015moles - 0.012moles = 0.003moles

Replacing in H-H equation:

pH = 3.25 + log [0.012moles] / [0.003moles]

<h3>pH = 3.85</h3><h3 />

c. At equivalence point all HNO2 reacts producing NaNO₂. The volume added of NaOH must be 100mL. That means the concentration of the NaNO₂ is:

0.15M / 2 = 0.075M

The NaNO₂ is in equilibrium with water as follows:

NaNO₂(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq) + Na⁺

The equilibrium constant, kb, is:

Kb = Kw/Ka = 1x10⁻¹⁴ / 5.6x10⁻⁴ = 1.79x10⁻¹¹ = [OH⁻] [HNO₂] / [NaNO₂]

<em>Where [OH⁻] = [HNO₂] = x</em>

<em>[NaNO₂] = 0.075M</em>

<em />

1.79x10⁻¹¹ = [X] [X] / [0.075M]

1.34x10⁻¹² = X²

X = 1.16x10⁻⁶M = [OH⁻]

pOH = -log [OH-] = 5.94

pH = 14-pOH

<h3>pH = 8.06</h3><h3 />

d. At this point, 5mL of NaOH are added in excess, the moles are:

5mL = 5x10⁻³L * (0.15mol / L) =7.5x10⁻⁴moles NaOH

In 100mL + 105mL = 205mL = 0.205L. [NaOH] = 7.5x10⁻⁴moles NaOH / 0.205L =

3.66x10⁻³M = [OH⁻]

pOH = 2.44

pH = 14 - pOH

<h3>pH = 11.56</h3>
5 0
2 years ago
In your discussion consider a SN2 reaction mechanism concept. Propose a modification of experimental procedure that would improv
Hitman42 [59]

Answer:

Here's what I get  

Explanation:

You may have done a Williamson synthesis of guaifenesin by reacting guaiacol with 3-chloropropane-1,2-diol.

A. Mechanism

Step 1

NaOH converts guaiacol into a phenoxide ion.

Step 2

The phenoxide acts as the nucleophile in an SN2 reaction to displace the Cl from the alkyl halide.

B. Improve the yield

You probably carried out the reaction in ethanol solution — a polar protic solvent.

You might try doing the reaction in a polar aprotic solvent— perhaps DMSO.

A polar aprotic solvent does not hydrogen bond to nucleophiles, so they become stronger.

C. Another method of ether synthesis —dehydration of alcohols

Sulfuric acid catalyzes the conversion of primary alcohols to ethers.

This is also a nucleophilic displacement reaction.

Protonation of the OH converts it into a better leaving group.

Attack by a second molecule of alcohol forms the protonated ether.

A molecule of water then removes the proton.

6 0
3 years ago
How many types of biodiversity Are there
Mashcka [7]
3
Species
Genetic diversity
Ecosystem diversity
8 0
3 years ago
Determine which reaction has the highest activation energy.
Ymorist [56]

Answer:

A.

Explanation:

4 0
2 years ago
Other questions:
  • Recycled r134a refrigerant cannot exceed what levels of contaminants
    15·1 answer
  • Consider the group 1A elements sodium (period 3), potassium (period 4), and rubidium (period 5). What would you predict about th
    9·1 answer
  • Justin B. Believes that the temperature lowering during the fall months is what causes the color of the leaves to change. He set
    9·1 answer
  • The density of aluminum is 2.7 g/cm3. A metal sample has a mass of 52.0 grams and a volume of 17.1 cubic centimeters. Could the
    10·1 answer
  • Liquid ammonia boils at –33.4ºC and has a heat of vaporization of 23.5 kJ/mol. What is its vapor pressure at –50.0ºC? (R = 8.314
    12·1 answer
  • Silver chloride is also known as <br>silver glance<br>silver copper glance<br>horn silver<br>all​
    6·1 answer
  • How does energy loss account for the relative proportions found in ecosystems.
    12·1 answer
  • An object with a mass of 4.0 kg has a force of 12.0 newtons applied to it. What is the resultant acceleration of the object?
    9·1 answer
  • An atom with5 protons 6 neutrons and 5 electrons has an atomic mass of Amy
    9·1 answer
  • An acid is hydrogen and one or more nonmetals. <br><br> Select one:<br> True<br> False
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!