1) Determine density of sample. (show your work WITH units)

Assume 1.5 grams of a metal and an 8 mL change in volume when the metal is placed in water.

2. Identify your sample by comparing the density of your sample with known

densities. This can be searched in your textbook or online.

Critical Thinking and Communication

3. Using the procedure in this experiment explain how the measured density of a substance is affected for each of the following:

 

1. Some of the water in the graduated cylinder splashes out when the sample is added.
2. Air bubbles adhere to the submerged sample when the volume of sample plus water is measured. 

4. Describe 3 or 4 other potential sources of error that may affect your results and explain why that will change the calculated answer.

 **Write each source and explanation in a separate paragraph, using complete sentences.**

5. Explain the process that allowed you to take measurements of mass and volume and determine the identity of the unknown metal.

1) Density = 0.1875 g/ml.

2)There is no metal with density of 0.1875 g/ml. The closet element is gaseous helium with density of 0.1785g/ml.(Assuming that the stated weight is 15 grams, density obtained is 1.8750 g/m. The metal close to this is Cesium with density of 1.879 g/ml hence the sample is cesium).

3 I) Splashing of water upon adding the sample implies that some water is lost hence the volume change of water obtained is lower than the actual change hence density obtained is higher than the actual density.

II) Air bubbles around the sample increases the volume of the sample hence the volume change obtained is larger than the actual volume of water that is relative to the volume of the sample thus the density obtained is less than the actual density.

4) i)Porosity of the sample. If the sample is porous, it will absorb some water hence the volume change upon adding the sample will be less than the actual change if the sample were not porous. This results to large density calculated than the actual density.

ii) Temperature changes. Changes in temperature may cause the sample to expand or contract resulting to variation of the density obtained. the liquid used in measuring the volume may also be subjected to volume changes affecting accurate measurement of the volume changes when the sample is introduced.

iii) Uncertainty of weighing. While weighing some sample loss occurs resulting to biased density measurement such that higher density is obtained than the actual one.

5.Buoyance process. In this process the liquid is placed in a measuring cylinder and a sample introduced to cause displacement of water. The change is recorded and and the volume displaced is equal to the volume of the sample.

Step-by-step explanation

3.In buoyance measurement, any error that result in displacement of less water than the actual volume that can be displaced results in obtaining density that is higher than the actual density.

4.Factors affecting the accuracy of calculated density include porosity of the sample, temperature, bubbles and uncertainty associated with weighing such weight loss.

5.Displacement water or any other liquid by known sample weight facilitates density determination by dividing the sample mass by volume of the fluid displaced.

Please see the attached file for the complete solution