✅ 5. Required Practical: Density Tests (P6)

Question 1

What is the Aim of this Practical?

Answer 1

The aim of the practical is to carry out an experiment to measure the mass and volume of given solids and liquids shaped as regular and irregular three-dimensional bodies. You will use your measurements to calculate the densities of the materials. You write a report about your experiment, and evaluate your method.

Question 2

Hypothesis for this Practical

Answer 2

My prediction is that either the metal and then the rock will be the most dense, as they Re the hardest and heaviest materials out of the lot, therefore suggesting the particles inside are more densly packed together. However, I believe that the wood will be the least dense, as it is the lightest and most soft material, as the particles inside may not be so closely packed together.

Question 3

Health and Safety for this Practical

Answer 3

• Water can spill and cause a slip hazard - keep paper towels nearby to clean up spillages
• Dropping heavier objects onto your foot could be painful - don’t hold it when your hands are wet or for extended periods of time.

Question 4

Equipment Needed for the Density Tests Practical

Answer 4

• Regular-shaped solid material
• Irregular-shaped solid material
• Liquid in a regular-shaped container
• Balance
• Ruler (30 cm is long enough)
• Measuring cylinder
• Eureka Can/Cylinder
• Water

Question 5

Method For Testing The Density of a Regular Solid Object

Answer 5

For a solid, regular object, use a ruler to measure the length (l), width (w) and height (h) of the object. Place the object on the top pan balance and measure its mass. Calculate the volume of the cube using (l×w×h). Use the measurements to calculate the density of the object.

Question 6

Method For Testing The Density of a Irregular Solid Object

Answer 6

For a solid, irregular object, place the object on the top pan balance and measure its mass. Fill a eureka cylinder so that there is enough water to go all the way up to the spout. Carefully lower the object into the cylinder. Measure the volume of the water that came out of the spout. This is the volume of the object. Use the measurements to calculate the density of the stone.

Question 7

Method For Testing The Density of a Liquid Object

Answer 7

For a liquid, place the measuring cylinder on the top pan balance and measure its mass. Pour a predetermined volume of liquid (eg water) into the measuring cylinder and measure its new mass. Also, measure the volume of the water. Subtract the mass of the beaker from the mass of the beaker and water. This is the mass the predetermined volume of water. Use the measurements to calculate the density of the water.

Question 8

What is the Independant Variable

Answer 8

In this experiment, it seems as the Independant Variable is the different material because it is the variable that his altered throughout the experiment to see the effect it has on the time.

Question 9

What is the Dependant Variable

Answer 9

The Dependant Variable is the density. This is because the dependant variable is the variable that is being tested and measured for

Question 10

What are the Control Variables

Answer 10

The Control Variable is the room temperature, and the amount of water used. These are control variables because these are kept the same throughout the experiment to ensure thst it is kept as a fair test.

Question 11

How to lay out the Results Table

Answer 11

I set the results table out in 5 main columns, which included:

• The objects on the left
• Then the mass, g (with 3 sub-columns for the 3 seperate tests)
• Then the volume, cm^3 (with 3 sub-columns for the 3 seperate tests))
• Then the density, g/cm^3 (with 3 sub-columns for the 3 seperate tests))
• And finally a column for the average density for each object, in g/cm^3

Question 12

How to Set out the Graph and what it should look like

Answer 12

For the graph, I used a bar chart. Tne average density (g/cm^3) was placed on the Y-Axis, while the Objects (wood, metal, rock, water) were placed on the X-Axis

In terms of highest density to the lowest density, the bar chart went:

1. Metal
2. Rock
3. Water
4. Wood

Question 13

Conclusion for the Density Tests Practical

Answer 13

Overall, the results showed that the metal was by far the most dense out of all of the materials tested (also considerably more dense than the rock), partly proving my hypothesis for the most dense material right. The metal had a heavy average mass of 250.23g (far larger than the other materials) and an average volume of 31.5cm^3 (slightly more than the other materials), which is both what made it the most dense.

The least dense material was in fact the wood, proving my hypothesis right. This is because it had the lightest average mass of 7.21g, and the average lightest volume of 13.4cm^3. These two factors put together ensured it had the lightest average density of 0.54g/cm^3, meaning that it can actually float on water, which is more dense at 0.97g/cm^3.

Question 14

Evaluation for the Density Tests Practical

Answer 14

Overall, there aren’t too many ways in which this practical could really be improved, but there are a few. It’s important to know that densities calculated from measurements are subject to experimental error. This could be because:

The top pan balances used by different people may not be identically calibrated
-Use an accurate balance, and make sure yourself that it is fully calibrated correctly

The resolution of the measuring cylinders may be different, causing different values for the volume to be recorded
-Use a burette instead of a measuring cylinder as it has a smaller degree of accurate
and using a rule instead of a ruler to record more precise measurements.