G. C. 1-1 Identification of Metals 7 G. C. I-I: GROUP DISCUSSION QUESTIONS

1. Which way turned out to be the most accurate to determine the density of the metal, calculation from a single data point, slope of the manually drawn or the computer-created graph? What do you think, why?

2. A sample of an unknown alloy has a density of 10.582 g/cm³. If its components come from the five met als from today's lab, can you estimate what the predominant metal is? If so, which is it?

3. Describe how you would modify the experiment if you had a metal that floated on the water. How would you change the experiment to obtain the volume of the metal?

4. Since the metal sample is a cylinder is there another way you could determine the volume of the cylin der other than via displacement of water? If so, describe how you would go about doing so and include any relevant equations. Hint: Think back to geometry.

5. Do you think determining the density using this method would be more accurate than those performed by today's experiment? Hint: Consider different errors in determining volume via water displacement versus the method described in Question 4 above.

1. Which way turned out to be the most accurate to determine the density of the metal, calculation from a single data point, slope of the manually drawn or the computer-created graph? What do you think, why?

2. A sample of an unknown alloy has a density of 10.582 g/cm³. If its components come from the five met als from today's lab, can you estimate what the predominant metal is? If so, which is it?

3. Describe how you would modify the experiment if you had a metal that floated on the water. How would you change the experiment to obtain the volume of the metal?

4. Since the metal sample is a cylinder is there another way you could determine the volume of the cylin der other than via displacement of water? If so, describe how you would go about doing so and include any relevant equations. Hint: Think back to geometry.

5. Do you think determining the density using this method would be more accurate than those performed by today's experiment? Hint: Consider different errors in determining volume via water displacement versus the method described in Question 4 above.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%