This document describes a chemistry laboratory experiment to measure the density, specific gravity (SG), and API gravity of fluids. Two methods are used: a hydrometer method and a pycnometer method. The pycnometer method is found to be more accurate due to factors like temperature that can affect hydrometer readings. Calculations are shown to determine the SG and API gravity of a crude oil sample. The API gravity is found to be 47.84, indicating a paraffinic crude oil. Higher API gravity values correspond to crude oils that contain more gasoline and less sulfur.

1. Technical College Of Engineering
Petroleum and Energy Engineering Department
Chemistry Laboratory
1st
stage
(2016-2017)
Lab # 2(Density and Specific Gravity)
(Measurement of Density S.G and API gravity)
Prepare By:Zanyar nawzad hama ali
Date : 27/2/2017
Group : A

2. Aim :
 Calculate the density a substance from measurements of
it is mass and volume .
 Calculate the specific gravity of a liquid from it is density
 Compute the value of API (American petroleum
institute)
Introduction:
Determining the density, S.G and API gravity of the fluid is very
important to classifiedthe fuel . this experiment will show us how to
determining API and S.G via two method .
Density is mass per unite value or density is a characteristicproperty
of the substance. the density of the substance is the relationship
between the mass of the substance and how much space it takes up
(volume ).
API gravity is used to quantify the quality of petroleum products
and it has range that measures the quality . and it depended on S.G
the higher S.G the lowerAPIgravity .

3. Equipment :
 Granulate cylinder
 Hydrometer
 Scientific balance
 Pykno meter

4. Procedure :
Hydrometer method :
At first take a suitable graduate cylinder 500 ml and it should be
clean. the cylinder should be big enoughbecause when we up put the
hydrometer it should (move )floats easilyin the cylinder .
So, we fill cylinder with the sample (in out experiment we just used
dieselfor the method ) after filing the cylinder with the diesel we
allowedsufficient time for the hydro meter to come to rest. and when
the hydrometer is flowedfreely we took the scale reading. And at the
end we brought out the hydrometer and cleanedit.
Pico meter :
At first we took the emptied Pico meter and weight it (M1). Then we
filled the pyknometer with the sample that we wanted and weightit
again(M2) .(To yield the weight of the sample we subtract M2 from
M1)
The volume of the pyknometer that we used for kerosene was
5.305mland for dieselwas 4.928ml.
After those steps we measure the the density of fluid and API gravity
and specific gravity according to what we did in the lab.
API gravity =141.5/S.G(at15.6 cͦ
)-131.5
Note:
 API gravity >40 paraffinic (or light )basedcrude oil
 API gravity =33-40 mixed (or intermediate) basedcrude oil
 APIgravity< 33 naphthenic (asphaltic or heavy) basedcrude oil

5. Calculation:
M1 = 33.04 gm(empty)  m1 =mass of pyknometer
M2 = 71.97 gm( crude) m2 =mass of pyknometer with crude oil
M3 = 82.60 gm(water) m3 =mass of pyknometer with water
V1 = volume of crude oil V2 = volume of water
 Sp.Gr =
𝒅𝒆𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒔𝒖𝒃𝒔𝒕𝒂𝒏𝒄𝒆
𝒅𝒏𝒔𝒊𝒕𝒚 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓
Sp.Gr =
𝒎𝒂𝒔𝒔 𝒐𝒇 𝒄𝒓𝒖𝒅𝒆 𝒐𝒊𝒍
𝒗 𝟏
𝒎𝒂𝒔𝒔 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓
𝒗 𝟐
(V1=V2)
Sp.Gr=
𝒎𝒂𝒔𝒔 𝒐𝒇 𝒄𝒓𝒖𝒅𝒚 𝒐𝒊𝒍
𝒎𝒂𝒔𝒔 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓
=
𝒎𝒂𝒔𝒔 𝒐𝒇 𝒑𝒚𝒌𝒏𝒐𝒎𝒆𝒕𝒆𝒓 𝒘𝒊𝒕𝒉 𝒄𝒓𝒖𝒅𝒆 𝒐𝒊𝒍−𝒎𝒂𝒔𝒔 𝒐𝒇 𝒑𝒚𝒌𝒏𝒐
𝒎𝒂𝒔𝒔 𝒐𝒇 𝒑𝒚𝒌𝒏𝒐𝒎𝒆𝒕𝒆𝒓 𝒘𝒊𝒕𝒉 𝒘𝒂𝒕𝒆𝒓−𝒎𝒂𝒔𝒔 𝒐𝒇 𝒑𝒚𝒌𝒏𝒐
Sp.Gr =
𝑴𝟐−𝑴𝟏
𝑴𝟑−𝑴𝟏

𝟕𝟏.𝟗𝟕−𝟑𝟑.𝟎𝟒
𝟖𝟐.𝟔𝟎−𝟑𝟑.𝟎𝟒

𝟑𝟖.𝟗𝟑
𝟒𝟗.𝟓𝟔
 0. 7855
Temperature (T) of crude oil = 18 cͦ
CR or α = 0.00066
Sp.Gr( at 60cͦ for 15.6 cͦ)=Sp.Gr(at T)+ α ×( T -15.6)
Sp.Gr (at 60 cͦ for 15.6 cͦ) = 0.7855+ (0.00066)(21cͦ -15.6cͦ)
Sp.Gr = 0.789
API =
𝟏𝟒𝟏.𝟓
𝟎.𝟕𝟖𝟗
– 131.5 = 47.84 this value of (API) it mean

6. Discussion:
1- Explain which method is much accurate ?
Method two (pykometer is more accurate then the hydrometer and
the reasons belongs to those factorythat affectthe hydrometer like
temperature , carbondioxide and presence ofalcohol..
2- What are factoreffecting on the hydrometer ?
The factorthat effects the hydrometer are :
 Temperature that causes the change in density
 Carbon dioxide
 Presence ofalcohol
3- What are the advantage of API value ?
The more API gravity value of crude oil more expansive and more
effectualbecause it contain more gasoline and it is the most wanted
product at the whole world . the other advantage ofAPI gravity vale
that we can determine the sulfur contain in crude oil , the higher
value of API gravity mean the less containof sulfur , the high levels
of sulfur contains can be toxic and dangerous and cancause
breathing hazards .

7. Reference :
www.wikpedia.org
http://study.com
http://whatis.techtarget.com