Estimating Avogadro’s
Number
Name
Lab 7: Estimating Avogadro’s
Number Name
Lab partner N/A
©2014, Carolina Biological Supply 1
Company
, Estimating Avogadro’s
Number
Purpose: The purpose of this lab is to learn how to use Avogadro’s Number to
estimate the number of atoms, knowing the mass and volume of an object.
Pre-laboratory Questions
1. The stearic acid/hexane solution contains 0.1 g of stearic acid per 1 mL of
solution. What is the molarity of this solution?
Stearic acid’s molecular mass is 284.48 g/mol. The number of moles in 1 mL solution
is 0.1g /284.48 g/mol = 0.000352 mol.
Molarity is the number of moles in 1 L solution. 1ml = 0.001 L.
0.000352/0.001=0.352 mol/L.
Molarity is 0.352 M.
2. What is the largest area of a circle that can be made from a piece of thread
25.2 cm long (assume no knot)?
The area of a circle is 𝜋𝑟 #, where 𝜋 = 3.14.
Using a thread of 25.2 cm, we assume that that equals the circumference of the circle.
We divide 25.2 by 2 and by 3.14, and we get 4.01., which equals to 𝑟. We can now
proceed to use the formula to calculate the area of the circle: 𝜋4.01# = 𝟓𝟎. 𝟓 𝒄𝒎.
3. What is volume of one aluminum atom? (show your work)
To find volume, we use the formula Volume=mass/density. One aluminum atoms
has a mass of 4.48×10−23 g, and a density of 2.7 g/cm3.
The volume of one aluminum atom equals to 4.48×10−23 g/2.7 g/cm3 = 1.6599×10−23 cm3.
4. Research face-centered cubic structures on the web. What is the length of one
side of the crystal unit cell for aluminum? (show your work)
The face-centered cubic structure is a structure that has atoms in all corners and in
the centers of the cubic faces, and the atoms are packed so closely that they nestle
in the empty spaces between the atoms.
©2014, Carolina Biological Supply 2
Company
Number
Name
Lab 7: Estimating Avogadro’s
Number Name
Lab partner N/A
©2014, Carolina Biological Supply 1
Company
, Estimating Avogadro’s
Number
Purpose: The purpose of this lab is to learn how to use Avogadro’s Number to
estimate the number of atoms, knowing the mass and volume of an object.
Pre-laboratory Questions
1. The stearic acid/hexane solution contains 0.1 g of stearic acid per 1 mL of
solution. What is the molarity of this solution?
Stearic acid’s molecular mass is 284.48 g/mol. The number of moles in 1 mL solution
is 0.1g /284.48 g/mol = 0.000352 mol.
Molarity is the number of moles in 1 L solution. 1ml = 0.001 L.
0.000352/0.001=0.352 mol/L.
Molarity is 0.352 M.
2. What is the largest area of a circle that can be made from a piece of thread
25.2 cm long (assume no knot)?
The area of a circle is 𝜋𝑟 #, where 𝜋 = 3.14.
Using a thread of 25.2 cm, we assume that that equals the circumference of the circle.
We divide 25.2 by 2 and by 3.14, and we get 4.01., which equals to 𝑟. We can now
proceed to use the formula to calculate the area of the circle: 𝜋4.01# = 𝟓𝟎. 𝟓 𝒄𝒎.
3. What is volume of one aluminum atom? (show your work)
To find volume, we use the formula Volume=mass/density. One aluminum atoms
has a mass of 4.48×10−23 g, and a density of 2.7 g/cm3.
The volume of one aluminum atom equals to 4.48×10−23 g/2.7 g/cm3 = 1.6599×10−23 cm3.
4. Research face-centered cubic structures on the web. What is the length of one
side of the crystal unit cell for aluminum? (show your work)
The face-centered cubic structure is a structure that has atoms in all corners and in
the centers of the cubic faces, and the atoms are packed so closely that they nestle
in the empty spaces between the atoms.
©2014, Carolina Biological Supply 2
Company
