Question

Gather the digital scale, chalk, and a sheet of paper. Using the knowledge gained from Exercise 1, design an experiment to determine how many atoms of calcium are required to write your name with a piece of chalk (CaCO3). Record a detailed description of the experimental design in Panel 1: Experimental Design. Perform the experiment and calculate the number of calcium atoms required to write your name with a piece of chalk on a sheet of paper. Take a photo of your work and upload the image into Photo 1. Record a conclusion statement, such as “The number of calcium atoms required to write my name is ___.” in Panel 2: Conclusion Statement.

Weight of chalk before was 4.32 g

Weight of chalk after writing my name James Vasquez is 4.29g

Please write clearly.

Answer 1

The chemical composition of chalk is CaCO₃.

The atomic masses are

Ca: 40.078 g/mol

C: 12.011 g/mol

O: 15.999 g/mol

The gram molar mass of CaCO₃ = (1*40.078 + 1*12.011 + 3*15.999) g/mol = 100.086 g/mol.

Mass of chalk lost during the process = (4.32 - 4.29) g = 0.03 g.

Mol(s) CaCO₃ corresponding to 0.03 g = (0.03 g)/(100.086 g/mol)

= 2.997*10^-4 mol

Now 1 mol CaCO₃ contains 6.02*10²³ Ca atoms.

Number of Ca atoms in 2.997*10^-4 mol CaCO₃ = (2.997*10^-4 mol)*(6.02*10²³ atoms)/(1 mol)

= 1.804*10²⁰ atoms

≈ 1.8*10²⁰ atoms.

Thus, the number of Ca atoms lost during the writing process = 1.8*10²⁰ atoms (ans).