AnswerTherefore, you left approximately 1.202 x 10^23 molecules of CaCO3 on the concrete after drawing with a 25g chalk piece outside for 5 minutes.
Step-by-step explanation:
To solve this problem, we need to use the concept of conservation of mass, which states that matter cannot be created or destroyed, only transformed from one form to another. Therefore, the total mass of the chalk before and after drawing must be equal.
The mass of the chalk before drawing is 25 g. After drawing for 5 minutes, the mass of the chalk is 5 g. Therefore, the mass of chalk that was used for drawing is:
25 g - 5 g = 20 g
Next, we need to convert the mass of the chalk used to the number of molecules. The molar mass of CaCO3 is 100.09 g/mol, which means that one mole of CaCO3 contains 6.022 x 10^23 molecules.
To calculate the number of molecules of chalk used for drawing, we can use the following steps:
Calculate the number of moles of CaCO3 used:
20 g / 100.09 g/mol = 0.1998 mol
Calculate the number of molecules of CaCO3 used:
0.1998 mol x 6.022 x 10^23 molecules/mol = 1.202 x 10^23 molecules