The density of any material is its mass per unit volume. It is a physical property meaning that every material has a characteristic density. Therefore, density may be used to identify the material.
Knowledge of this property may also be used to predict behavior of an object placed in a fluid
(where a fluid can be liquid or gas). Most often water is the fluid of interest, and the ratio of a material’s density to that of water is called its specific gravity . In this lab, the specific gravity of several materials will be determined.
 Determine the specific gravity of several solids and a liquid.
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Spring scales
 Set of mass cubes
Wood blocks
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Lead sinkers
 Overflow cup
Spigot cup
 Beakers of unknown liquid
 Ring stands
 mass cylinder
1.
Select a block and measure and record its weight.
2.
Measure and record the mass of the overflow cup.
3.
Completely fill the spigot cup.
4.
Place the empty overflow cup beneath the spigot.
5.
Completely submerge the block into the spigot cup, hanging it by the spring scale.
6.
Once the overflow is complete, measure and record the block’s weight.
7.
Remove the overflow cup, place it on the bar scale, and record its mass .
8.
Determine the weight (in Newtons) of the displaced water by subtracting the mass of the empty cup and converting the mass to weight, recalling that weight is measured in
Newtons which is equal to kg·m/sec 2 .

9.
Repeat the steps for each of the blocks. Note that all of the blocks are of the same volume
(the amount of water displaced each time will be the same). You need only perform the weight determination of displaced water once, using the same value then for all of the blocks.
10.
At this point, you should have three measurements for each block : weight in air, weight in water, and weight of displaced water.
1. Calculate the specific gravity (SG) of each block using the following equations:
SG
1
= (Weight in air)/(Weight of displaced water)
SG
2
= (Weight in air)/(Weight in air - Weight in water)
2. Mathematically compare the specific gravities calculated for each block to determine the percent difference between.
3. Which specific gravity measurement would you consider more accurate and why?
1.
Measure and record the weight of a block of wood.
2.
Affix enough sinkers to the block of wood sufficient to sink it.
3.
Measure and record the weight of the system when only the sinkers are immersed.
4.
Measure and record the weight when the entire system is immersed.
Calculate the specific gravity of the wood block according to:
SG = (Weight in air)/(weight of sinkers - weight of sinkers plus block)
1.
Measure and record the weight of a small cylinder.
2.
Measure and record the weight of the cylinder when fully immersed in a beaker of water.
3.
Remove the cylinder from the water and dry it off.
4.
Measure and record the weight of the cylinder in an unknown fluid by suspending spring scale from a horizontal bar attached to a ring stand.
5.
Repeat the steps for every unknown liquid provided.
Calculate the specific gravity of the liquids tested according to: o SG = (Weight in air - Weight in unknown)/(Weight in Air - Weight in water)
1.
How does the specific gravity of the wood block compare to those calculated for the metal blocks?
2.
What can you concluded about objects with specific gravities above or below 1.0?

3.
Which is denser, ice or water? Why?