Determine Atomic Size Lab

Introduction: This experiment's purpose is to calculate small values (molecular and atomic size) in different phases, such as a gas, liquid, and solid by using practical methods. If the molar mass is known, one can estimate the atomic size through practical measuring techniques with little experimental error. This experiment consists of measuring a block of a solid element (Copper and Zinc), measuring the volume of the lead pellets, and measuring the amount of carbon dioxide gas in a balloon. These experiments will allow one to estimate the atomic or molecular size by using doable measurements and calculations.

Experimental Procedure:

Found the mass of a cylinder of Copper and the mass of a cylinder of Zinc on an electric scale, recorded

Added 20 ml of water and weighed the graduated cylinder again.

Measured the diameter and length of the spherical dry ice using a tape measurer.

Measured the mass of the dry ice on the electric scale.

Placed the dry ice into a flask, covered the opening of the flask with a balloon, and placed tape around the balloon in order for the carbon dioxide gas not be able to leak.

Waited for 40 minutes for the dry ice to turn into carbon dioxide, then measured the circumference of the balloon to figure out the diameter and volume of the balloon.

Discussion: When finding the atomic size for the cubic and spherical atomic model, I found that the experimental error percentages were not far off. There was more of a percentage error for Copper due to random errors when calculating the cubical atomic model, since the cylinder was only weighed once. This cause would also be accurate for the other cubical model of Zinc and both the Copper and Zinc spherical atomic models. If the cylinders were weighed multiple times and an average was taken, then the experimental errors may have decreased due to finding the closer actual value. Both of the spherical atomic models were closer to the actual atomic diameters than when compared to the cubical model. This is because the empty space between the atoms are taken into account. Both experimental values of Copper and Zinc were relatively close to the actual value, but random errors or human errors--measuring the solid cylinders inaccurately and producing an inaccurate packing coefficient when measuring the volume of water poured into the lead pellets--will have thrown these measurements off. By these measurements being off, it lead to experimental