Ingrid Castillo12-16-2012Period 5Larkin

An Analysis of Chalk Writing

Introduction:

Stoichiometry is a branch of chemistry that deals with conversion of units. The purpose of the

lab it was to calculate the average number of particles of chalk that it takes to write a person’s

name. A scientist named Amedeo Avogadro developed a new unit called a mole which is 6.02

x 10 particles that was named after him. Avogadro’s number is the number of atoms in 12 g of

carbon 12. In order to convert a mole to particles or particles to mole; an equality is needed in

order to do a conversion factor. A conversion factor is a numerical factor used to multiply or

divide a quantity when converting from one system of units to another. For example, to convert

3 moles of carbon to particles of carbon; 3 mole moles of C needs to multiply by Avogadro’s

number which is 6.02 x 10. Also, the mass in grams of one mole of substance is called molar

mass; each element has its own unique molar mass by adding the weight of all the atoms of the

chemical. Molar mass is used as conversation to relate the amount of a substance to its mass.

Procedures:

1. The students obtained chalk, paper for each member of the group and also a scale.

2. The paper was weighed on the scale and then the weight of the paper was recorded on

paper.

3. Then after recording the weight of the paper, the students wrote their name on the

paper using chalk.

4. The paper was weighed again and then a new weight was recorded.

5. The data from each member of the group was obtained and it was also recorded on the

results table.

Ingrid Castillo12-16-2012Period 5LarkinResults:

Table 1: Chalk Mass Data for 5 Elements

Avogadro's Number 6.02E+23

Molar Mass of Caco3 100

Scientist Name

Initial Paper Mass

Final Paper Mass

Mass of CaCO3

used Mole of CaCO3

Particles of CaCO3 used

Ingrid Castillo 4.6g 4.7g 0.1g

1.00E-03 Mole of CaCO3

6.020E+20 particles of CaCO3

Jose Torres 4.6g 4.8g 0.2g

2.00E-03 Mole of CaCO3

1.204E+21 particles of CaCO3

Angela Rodriguez 4.6g 4.9g 0.3g

3.00E-03 Mole of CaCO3

1.806E+21 particles of CaCO3

Eduardo Fuentes 4.6g 4.9g 0.3g

3.00E-03 Mole of CaCO3

1.806E+21 particles of CaCO3

Average

1.355E+21 particles of CaCO3

Ingrid Castillo12-16-2012Period 5LarkinCalculations:

Molar Mass of CaCo3:

40Cag/moles Ca +12g/moles of C + 48g/moles of O3

= 100g/moles of CaCO3

Mass of Chalk used (Ingrid):

4.6g - 4.7g = .1g

Particles of Chalk used (Ingrid):

.1g of CaCO3 x 1 moles CaCO3

100g/moles of CaCO3

= .001mol CaCO3

Average particles of Chalk used:

6.020E+20 particles of CaCO3 + 1.204E+21 particles of CaCO3 + 1.806E+21 particles of CaCO3 +

1.806E+21 particles of CaCO3

= 1.355E+21 particles of CaCO3

Ingrid Castillo12-16-2012Period 5LarkinConclusion:

The purpose of the lab was met by calculating the average number of particles which is

1.355E+21 particles of CaCO3. The average number of particles of chalk needed to write

someone’s name would be 1.355E+21 particles of CaCO3.The molar mass of chalk was found

by adding the weight of all the atoms of the chemical that each element has. Then to convert

the mass of chalk to amount; the first step is to convert mass of chalk to moles of chalk by

setting up a conversion factor that will cancelled mass of chalk. Then multiply moles of chalk by

Avogadro’s number which is 6.02E+23 in order to get the particles of chalk. The data was used

to find the average particles of CaCO3 by adding up all the particles of each individual amounts

for each name and then dividing by the number of members that were in the group.