Module 03 Assignment

Instructions: Write out a linear equation to answer each question.

1. How many molecules of oxygen are found in 3.00 moles of oxygen?

1 mol of any particle=6.023x1023 number of particles

1 mol of oxygen= 6.023x1023 molecules of oxygen

3.00 moles of oxygen= (3.00x6.023x1023)molecules of oxygen

Therefore the of molecules found in 3.00 moles of oxygen=1.81x1024 molecules of oxygen

2. How many grams are in 5.87x1021 molecules of sulfur?

Number of mole of sulfur=5.87x1021/6.022x1023 mol

Which results to = 9.7476x10-3

Molar mass of sulfur molecule= 8(32.065)g/mol

Which gives =256.52 g/mol

Mass of sulfur=(number of mole of sulfur molecule)x(molar mass of sulfur molecule)

Hence =(9.7476x10-3 mol) (256.52g/mol)

Which results to =2.5004g

3. How many atoms are found in 5.20 g of magnesium (Mg)?

Molar mass of Magnesium (Mg) =24g

Mole of Magnesium in 4.20g=4.20g/24g mol

Which gives =0.175mol

0.175 mole=(6.023x1023 x 0.175)atoms

Hence answer =1.054x1023

=1023 atoms

4. How many atoms are found in 3.45 g of CO2?

Mass/molar mass= the number of molecules/NA=moles

Molar mass of CO2 =44g/mol Also Given mass of CO2 =3.45g/mol

3.45/44= number of molecules/6.023x 1023

Number of molecules=4.72x1022 molecules. Hence (3 x4.72x1022)

Which gives the answer as =1.42x 1022 atoms

Instructions: Calculate the mass percent composition of a compound. Show all of your work.

5. Calculate the mass percent of 0.485 g of H, which reacts with oxygen to form 2.32 g H2O.

Mass of % H = mass of H/ total mass of sample x100%

Therefore, 0.485x2/ 2.32 x100%

Hence the Mass % of H=41.81%

6. Calculate the mass percent of manganese (Mn) in potassium permanganate (KMnO4).

%Mg = (54.94x1mol/158)x100 -> 0.348x100

Therefore, %Mg = 34.8%

Instructions: Calculate the empirical or molecular formula for compounds. Show all of your work.

7. A 2.87 g sample of carbon reacts with hydrogen to form 3.41 g of car fuel. What is the empirical formula of the car fuel?

Weight of carbon = 2.87 g, Weight of car fuel =3.41 g

Weight of hydrogen =(3.41-2.87)

Which gives =0.54 g

Hence, the % of C =2.87/3.41 = 0.8416 x 100%=84.2%

% of H =100%-84.2% =15.8%

Which results to the formula as= C4H9

8. Glucose is a carbohydrate that contains carbon, hydrogen, and oxygen. The empirical formula of glucose is CH2O, and its molar mass is 180.12 g/mol. Find the molecular formula of glucose.

180.12 divided by 30.027 = 6

Hence the molecular formula= C6H12O6

Chemical Bonding

Instructions: Draw the Lewis Structures for the following molecules. There are free software programs available online that will allow you to draw these structures. You can also use drawing tools on your computer or freehand it, take a picture and insert it into this document.

1. ZnCl2

..

Zn:Cl:

..

2. CH4

H

..

H:C:H

..

H

3. NI3

.. .. ..

:I:N:I:

.. .. ..

:I:

..

4. H2O

..

H:O:H

..

Instructions: Draw the resonance structures for the following compounds.

5. NO3-

.. .. ..

:O-S-O:

.. I ..

:O:

..

Instructions: Give the molecular geometry and the bond angles for the following compounds.

6. H2O

.. ..

O

/ \

H H

Bent 104.5 degrees

AX2F

7. CCI4

..

:Cl:

.. I ..

:Cl-C-Cl:

.. I ..

:Cl:

..

Tetrahedral

109.5 degrees

AX4N

8. CO2

.. .. ..

O::C::O

.. .. ..

Linear, 180 degrees

AX2X

9. NH3

..

H-N-H

I

H

..

N

/ I \

H H H

Trigonal pyramidal

<120 degrees

Instructions: There are various types of covalent bonds. Determine if the following molecules are polar, nonpolar, or ionic compounds.

10. NaCl

Ionic Compound

11. CH4

Nonpolar

12. BH3

Nonpolar

13. H2O

Polar

14. CHCI3

Polar

Naming Acids

Instructions: Provide the name of each of the following acids.

1. HBr- Hydrobromic Acid

2. HF- Hydrofluoric Acid

3. HC2H3O2- Acetic Acid

4. HNO3 – Nitric Acid

Instructions: Provide the molecular formula for the following acids.

5. Hydrocyanic acid- HCN

6. Phosphoric acid- H3PO4

References

Umemoto, K., & Hirose, K. (2020). Chemical compositions of the outer core examined by first-principles calculations. Earth and Planetary Science Letters, 531, 116009.

Zhao, L., Pan, S., Holzmann, N., Schwerdtfeger, P., & Frenking, G. (2019). Chemical bonding and bonding models of main-group compounds. Chemical Reviews, 119(14), 8781-8845.