**Discussion
Instructions Density
of Water** **Data
Sheet #1 Data Sheet #2**

**Instructions**

**Specific Gravity of a
Solid:**

The specific gravity (SG) of a
material is the ratio of its density to that of water at the same
temperature
and pressure. The difference between the weight of a solid in air and
under
water is equal to the weight of water displaced by the volume of the
sample:

SG = (weight in air)/(weight in air - weight under water) Eq 1

1. Select water as the liquid and select a solid sample.

2. Tare the balance.

3. Selectsample positionasweigh in airand record the value.

4. Selectsample positionasweigh under liquidand record the value.

5. Repeat steps 2-4 at least twice and calculate values forSGwithEq 1.

6. Average your results and estimate the uncertainty of this value.

**Volume of a Solid and Density
of a Solid:**

** **All fluids,
including
air, exert a buoyancy effect. The weight of a solid immersed in a fluid
(**W _{F}**) is related to the weight in vacuum (

W_{F}=W._{Vac}- VD_{F}

V = (W._{A}-W_{W})/(D_{W}- D_{A}) Eq 2

1. Selectwateras the liquid and selectglassas the solid sample.

2. Tare the balance.

3. Selectsample positionasweigh in airand record the value.

4. Selectsample positionasweigh under liquidand record the value.

5. Repeat steps 2-4 at least twice and calculate values forVto four significant digits withEq 2.

6. Average your results and estimate the uncertainty of this value.

The density of the glass
sample can be calculated by correcting the weight in air to the weight
in vacuum and dividing by the volume:

**
D_{sample} = (W_{Vac}/V) = (W_{A}/V) + D_{A
}Eq 3.
**

**The densities of other
solids may
be determined to about ± 0.1% by this method.
**

**Density of a Liquid:**

After determining the volume (**V**)
of the glass sample (or any other solid), the densities of other
liquids
(**D _{L}**) may be determined by the difference between the
weight of the glass sample in air (

D_{L}= D_{A}+ (W_{A}- W_{L})/VEq 4.

1. Select a liquid and selectglassas the solid sample.

2. Tare the balance.

3. Selectsample positionasweigh in airand record the value.

4. Selectsample positionasweigh under liquidand record the value.

5. Repeat steps 2-4 at least twice and calculate values forDto four significant digits with_{L}Eq 4.

6. Average your results and estimate the uncertainty of this value.