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
Brums [2.3K]
3 years ago
5

The osmotic pressure of a solution containing 2.04 g of an unknown compound dissolved in 175.0 mLof solution at 25 ∘C is 2.13 at

m . The combustion of 22.08 g of the unknown compound produced 36.26 g CO2 and 14.85 g H2O.
What is the molecular formula of the compound (which contains only carbon, hydrogen, and oxygen)?
Chemistry
1 answer:
kherson [118]3 years ago
4 0

<u>Answer:</u> The molecular formula of the compound is C_4H_{10}O_4

<u>Explanation:</u>

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

\pi=iMRT

Or,

\pi=i\times \frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}\times RT

where,

\pi = osmotic pressure of the solution = 2.13 atm

i = Van't hoff factor = 1 (for non-electrolytes)

Given mass of compound = 2.04 g

Volume of solution = 175.0 mL

R = Gas constant = 0.0821\text{ L atm }mol^{-1}K^{-1}

T = temperature of the solution = 25^oC=[273+25]=298K

Putting values in above equation, we get:

2.13atm=1\times \frac{2.04\times 1000}{\text{Molar mass of compound}\times 175.0}\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\\text{Molar mass of compound}=\frac{1\times 2.04\times 1000\times 0.0821\times 298}{2.13\times 175.0}=133.9g/mol

  • <u>Calculating the molecular formula:</u>

The chemical equation for the combustion of compound having carbon, hydrogen and oxygen follows:

C_xH_yO_z+O_2\rightarrow CO_2+H_2O

where, 'x', 'y' and 'z' are the subscripts of carbon, hydrogen and oxygen respectively.

We are given:

Mass of CO_2=36.26g

Mass of H_2O=14.85g

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

<u>For calculating the mass of carbon:</u>

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 36.26 g of carbon dioxide, \frac{12}{44}\times 36.26=9.89g of carbon will be contained.

<u>For calculating the mass of hydrogen:</u>

In 18 g of water, 2 g of hydrogen is contained.

So, in 14.85 g of water, \frac{2}{18}\times 14.85=1.65g of hydrogen will be contained.

Mass of oxygen in the compound = (22.08) - (9.89 + 1.65) = 10.54 g

To formulate the empirical formula, we need to follow some steps:

  • <u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon = \frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{9.89g}{12g/mole}=0.824moles

Moles of Hydrogen = \frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1.65g}{1g/mole}=1.65moles

Moles of Oxygen = \frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{10.54g}{16g/mole}=0.659moles

  • <u>Step 2:</u> Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.659 moles.

For Carbon = \frac{0.824}{0.659}=1.25\approx 1

For Hydrogen = \frac{1.65}{0.659}=2.5

For Oxygen = \frac{0.659}{0.659}=1

Converting the mole fraction into whole number by multiplying the mole fraction by '2'

Mole fraction of carbon = (1 × 2) = 2

Mole fraction of oxygen = (2.5 × 2) = 5

Mole fraction of hydrogen = (1 × 2) = 2

  • <u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : H : O = 2 : 5 : 2

The empirical formula for the given compound is C_2H_5O_2

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

n=\frac{\text{Molecular mass}}{\text{Empirical mass}}

We are given:

Mass of molecular formula = 133.9 g/mol

Mass of empirical formula = 61 g/mol

Putting values in above equation, we get:

n=\frac{133.9g/mol}{61g/mol}=2

Multiplying this valency by the subscript of every element of empirical formula, we get:

C_{(2\times 2)}H_{(5\times 2)}O_{(2\times 2)}=C_4H_{10}O_4

Hence, the molecular formula of the compound is C_4H_{10}O_4

You might be interested in
What is a substance and what are the two types of substances?
masha68 [24]
A pure substance has a constant composition and cannot be separated into simpler substances by physical means. There are two types of pure substances: elements and compounds. Elements: are pure substances made up of only l type of atom. Atoms of the same element are identical in properties.
6 0
3 years ago
Read 2 more answers
How many protons does nonradioactive carbon 13 have?
IgorC [24]
Non radioactive carbon 13 has 7 protons per atom.
7 0
3 years ago
14. How do you describe an atom in which the number of protons is equal
masha68 [24]
The number of protons in the nucleus of the atom is equal to the atomic number (z) and the number of electrons in a neutral atom is equal to the number of protons
8 0
3 years ago
Dry ice, or solid cabon dioxide, has the molecular formula of CO2. How should you classify it?
Marina86 [1]
You  should classify it as  co2 solid as CO2(s) and that small left comes to the bottom right hand side and dry ice is a form of liquid carbon dioxide so u should write it as CO2(l) and that L comes to the bottom right hand sise
6 0
3 years ago
Which list accurately identifies the hierarchy of space from largest to smallest?
katovenus [111]
D)Universe, galaxy, solar system, moon
4 0
3 years ago
Other questions:
  • 10: Convert 77.0 L at 18.0 mmHg to its new volume at standard pressure.
    7·1 answer
  • Which statement accurately describes why air pressure decreases as altitude increases? As you increase altitude the temperature
    7·1 answer
  • Describe the basic particle from which all ements are made
    7·2 answers
  • Convert 1.25 kg into grams
    11·1 answer
  • What type of bonds do inorganic compound make
    11·1 answer
  • Enter your answer in the provided box. To draw a Lewis structure, first add the number of outer (valence) electrons contributed
    10·1 answer
  • Convert 4.8 moles of calcium carbonate to<br> particles.
    15·1 answer
  • 4. Juan tiene un cilindro de 40 libras herméticamente cerrado con gas propano y lo conecta mediante una válvula a otro cilindro
    7·1 answer
  • The density of aluminum is 2.70 g/mL. The volume of a solid piece of aluminum is 1.50 ml. What is its mass?
    8·1 answer
  • What type of solvent would be required to dissolve nonpolar compounds?
    13·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!