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How can the density of unknown liquids be determined?

Date : ...............................................................

Partners : ...............................................................

...............................................................

Grade : ...............................................................

PURPOSE : To determine the density of unknown liquids.

EQUIPMENT and MATERIALS:

Equipment

 

Chemicals and Other Materials

• Graduated cylinder, 10 mL

(1)

• Unknown liquid

• Beaker, 100 mL

(1)

 

• Balance

(1)

 

PRE-LAB DISCUSSION

Density is a characteristic property of matter. In order to determine density, mass and volume of substance must be determined.

density =

mass (g)

volume (cm3)

Mass of substances can be determined with a balance. Volume of a liquid can be measured with a graduated cylinder.

PROCEDURE

Set-up

Figure

Weigh the mass of a clean and dry 10 mL graduated cylinder and record the result in the Table in “Observations and Data Tables”.

Procedure

1.Take your unknown liquid with 100 mL beaker from your instructor.

2. Put some amount of the unknown liquid into the graduated cylinder.

3.Read the volume of unknown liquid as seen in the Figure. Record the result in the Table in “Observations and Data Tables”.

4.Weigh the mass of graduated cylinder which includes the unknown liquid with balance. Record the result in the Table in “Observations and Data Tables” as total mass.

Experiment – 1 How can the density of unknown liquids be determined?

13

 

OBSERVATIONS AND DATA TABLES

1.Record your measurements in the Table below.

Mass of graduated

 

 

Total mass

 

 

Mass of the liquid

 

 

Volume of the liquid

cylinder (mC)

 

 

(mT)

 

 

(mT – mC)

 

 

(VL)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

..................................

g

 

..................................

g

 

..................................

g

 

.................................. cm3

CALCULATIONS

Density of unknown liquid (d=m/V) = ..................

g / ..................

cm3 = ..................

g/cm3

EVALUATIONS AND CONCLUSIONS

1.Compare your result with the results obtained by the other groups. What can be the reason of the difference?

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

2.Is density always enough to distinguish liquids itself? Explain.

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

Experiment – 1 How can the density of unknown liquids be determined?

14

How can the density of regular and irregular objects be determined?

Date : ...............................................................

Partners : ...............................................................

...............................................................

Grade : ...............................................................

PURPOSE : To determine the density of regular and irregular object.

EQUIPMENT and MATERIALS:

Equipment

 

Chemicals and Other Materials

• Graduated cylinder, 50 mL

(1)

• Regular object

• Balance

(1)

• Irregular object

• Ruler

(1)

• Thread

PRE-LAB DISCUSSION

Mass of objects can be determined by a balance. The volume of a regular object is calculated by multiplying their dimensions. On the other hand, volume of an irregular object

can not be determined as above. Their volume can be determined according to the amount of water which is displaced by them in a graduated cylinder.

PROCEDURE

Set-up

 

 

— Weigh the mass of the given regular object by equal

Figure

arm balance and record the result in the Table in “Ob-

servations and Data Tables”.

 

 

 

 

Weigh the mass of the given irregular object by equal arm balance and record the result in the Table in “Observations and Data Tables”.

Add 20 mL of water to the 50 mL graduated cylinder. Record the water volume in the Table in “Observations and Data Tables”.

Procedure

1.Measure the dimensions of the regular object by a ruler. Record the results in the Table in “Observations and Data Tables”.

2.Tie the irregular object with thread.

3.Immerse the object in the water in the graduated cylinder by holding the thread from other edge as seen in the Figure.

4.Read the final water volume in the graduated cylinder. Record the result in the Table in “Observations and Data Tables”.

Experiment – 2 How can the density of regular and irregular objects be determined?

15

 

OBSERVATIONS AND DATA TABLES

1.Record your measurements on regular object in the Table below.

Mass of the

 

 

Dimensions of the object

 

regular object

 

 

 

 

 

 

 

 

 

X

 

 

Y

 

 

Z

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

............... g

 

...........

cm

 

........... cm

 

...........

cm

 

 

 

 

 

 

 

 

 

2.Record your measurements on irregular object in the Table below.

Mass of the

 

Volume of water

 

irregular object

 

 

 

 

 

 

Before

 

 

After

 

 

 

 

 

 

 

 

 

 

........... g

 

........... cm

 

...........

cm

Volume of the object

(X x Y x Z)

........... cm3

Volume of the

object

........... cm3

CALCULATIONS

Density

of regular object (d=m/V) = ..................

/ ..................

= ..................

g/cm3

Density

of irregular object (d=m/V) = ..................

/ ..................

= ..................

g/cm3

EVALUATIONS AND CONCLUSIONS

1.Compare your result with the results obtained by the other groups. What can be the reason of the difference?

...........................................................................................................................................................................................

...........................................................................................................................................................................................

2.Can density of all irregular objects be determined by this method? Explain.

...........................................................................................................................................................................................

...........................................................................................................................................................................................

3.Suggest a method to determine the density of an irregularly shaped plastic object which has lower density of [0,8 - 1,0 g/mL]. You are given alcohol (ethanol) and water. (dethanol= 0,79 g/mL, dwater = 1,0 g/mL)

...........................................................................................................................................................................................

...........................................................................................................................................................................................

Experiment – 2 How can the density of regular and irregular objects be determined?

16

How can pure substances be differentiated?

Date : ...............................................................

Partners : ...............................................................

...............................................................

Grade : ...............................................................

PURPOSE : To determine the boiling point of distilled water and salt solutions with different concentration. To identify substances by using boiling points.

EQUIPMENT and MATERIALS:

Equipment

 

• Timer

(1)

• Wire gauze

(1)

• Erlenmeyer, 250 mL

(1)

• Support base

(1)

• Burner

(1)

• Thermometer

(1)

• Support rod

(1)

• Rubber stopper, with two hole

(1)

• Stirring rod

(1)

• Bosshead

(1)

Chemicals and Other Materials

 

• Right-angled glass tube

(1)

• Universal clamp

(1)

Distilled water

 

• Balance

(1)

• Tripod

(1)

Table salt

 

PRE-LAB DISCUSSION

Compounds are matter that have two or more kinds of atoms and they are pure substances. Compounds have constant melting and boiling points but mixtures have not.

If you draw temperature versus time graph for compounds, you can obtain 2 straight lines. One of them is for melting

and the other one is for boiling. But in mixtures number of lines depends on the number of substances in the mixture. Because melting point and boiling point of each compound is different.

PROCEDURE

Set-up

Figure

 

Put the 250 mL erlenmeyer flask on the tripod and fix it on the support rod.

Place about 100 mL of distilled water into 250 mL erlenmeyer flask. Then add some small porcelain chips into the flask to regulate boiling.

Connect the thermometer and right-angled glass tube with rubber stopper, then close the flask with rubber stopper as in the Figure.

Note: Lubricate the holes of the rubber stopper with glycerol before inserting the thermometer. While doing so, hold the thermometer vertically.

Caution: Be sure that the thermometer is about 1 cm over the bottom of the erlenmeyer flask.

Procedure

1.Ignite the burner and heat the water until temperature become about 90oC. Record this temperature as initial temperature in the Table in “Observations and Data Tables”.

2.Continue heating and read the temperature every minute for ten minutes. Record the readings in the Table in “Observations and Data Tables”.

Experiment – 3 How can pure substances be differentiated?

17

 

3.Extinguish the burner and let the water to cool slightly.

4.Open the erlenmeyer flask, then put 10 g of table salt into the water and mix it with stirring rod.

5.Close the flask with rubber stopper which is connected with thermometer and right-angled glass tube.

6.Ignite the burner and reheat the solution up to about 90oC. Record this temperature as initial temperature in Table for 10 g of salt.

7.Continue heating and read the temperature every minute for ten minutes. Record the readings in the Table in “Observations and Data Tables” for 10 g of the salt.

8.Repeat the steps from 3 to 7 by adding 20 g of table salt and record the results in the Table in “Observations and Data Tables” for 30 g of the salt.

Note: Before starting step 8 make sure that volume of the water is about the same as the step 6.

OBSERVATIONS AND DATA TABLES

1.Record the read temperatures for distilled water in the Table below.

Time (minute)

 

0

 

1

 

2

 

3

 

4

 

5

 

6

 

7

 

8

 

9

 

10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Temperature

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.Record the read temperatures for salty water in the Table below.

Time (minute)

 

0

 

1

 

2

 

3

 

4

 

5

 

6

 

7

 

8

 

9

 

10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Temp

 

10 g salt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

30 g salt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EVALUATIONS AND CONCLUSIONS

1.Plot the measured values for water and the salt solutions on the millimetric papers below.

For distilled water

For 10 g of table salt

For 30 g of table salt

Experiment – 3 How can pure substances be differentiated?

18

2.How can you determine that a given liquid is pure or not? Explain.

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

3.Can the boiling point of liquids always be used to identify them?

...........................................................................................................................................................................................

...........................................................................................................................................................................................

4.How does the amount of dissolved salt in a pure liquid affect the boiling point? Explain.

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

5.Why temperature does not stay constant during the boiling of the salty water? Explain.

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

Experiment – 3 How can pure substances be differentiated?

19

 

Is the solubility of solids the same in water and in other liquids?

Date : ...............................................................

Partners : ...............................................................

...............................................................

Grade : ...............................................................

PURPOSE : To examine the solubility of solids in water, in ethyl alcohol and in olive oil.

EQUIPMENT and MATERIALS:

Equipment

 

Chemicals and Other Materials

• Test tubes

(3)

• Sodium chloride

• Test tube rack

(1)

• Calcium carbonate

• Graduated cylinder, 10 mL

(1)

• Sugar

• Balance

(1)

• Ethyl alcohol

• Rubber stopper

(3)

• Olive oil

 

 

• Distilled water

PRE-LAB DISCUSSION

A solution can be defined as homogeneous mixture of two or more substances. Solution has mainly two components; solute and solvent.

The solvent is the medium in which the solutes are dissolved. Water is a typical and very common solvent, but

there are many other solvents. Solubility of solids is different in different solvent. Solubility of solids in a solvent is related with their similarity in their structures. Polar solid dissolves in polar solvents. Nonpolar solid dissolves in non-polar solvents.

PROCEDURE

Set-up

Place three test tube into the test tube rack.

Add 10 mL of distilled water in each test tube with 10 mL graduated cylinder.

Weigh 2 g of each of sodium chloride, calcium carbonate and sugar.

Procedure

1.Put sodium chloride in the first test tube.

2.Close the test tube with a stopper and shake it vigorously for several minutes. Then place it into the test tube rack.

3.Put calcium carbonate in the second test tube and sugar in the third test tube. Then Repeat the step 2 for both salts. Record your observations in Table in “Observations and Data Tables”.

4.Let the mixtures rest for awhile. Compare the amount of salts remaining at the bottom of the tubes. Record your observations in the Table in “Observations and Data Tables”.

5.Repeat above steps by using ethyl alcohol and olive oil as a solvent instead of water. Compare the solubility of

solids in water, in ethyl alcohol and in olive oil. Record your observation in the Table in “Observations and Data Tables”..

Figure

Experiment – 4 Is the solubility of solids the same in water and in other liquids?

20

OBSERVATIONS AND DATA TABLES

1.Note your observations in the Table below.

Solubility of solids in water and other liquids (insoluble, low solubility, high solubility).

Solids

 

Solubility in water

 

Solubility in ethyl alcohol

 

Solubility in olive oil

 

 

 

 

 

 

 

Sodium chloride

Calcium carbonate

Sugar

EVALUATIONS AND CONCLUSIONS

1.Classify the substances as solvent and solute for all the experiments?

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

2.Compare the solubility of the substances in increasing order in water, ethanol and olive oil?

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

3.Can solubility always be distinctive property for all solids in a solvent? Explain

...........................................................................................................................................................................................

...........................................................................................................................................................................................

...........................................................................................................................................................................................

Experiment – 4 Is the solubility of solids the same in water and in other liquids?

21

 

Do all liquids dissolve in water?

Date : ...............................................................

Partners : ...............................................................

...............................................................

Grade : ...............................................................

PURPOSE : To examine the solubility of different liquids in water.

EQUIPMENT and MATERIALS:

Equipment

 

Chemicals and Other Materials

• Test tubes

(3)

• Carbon tetrachloride

• Test tube rack

(1)

• Ethyl alcohol

• Graduated cylinder, 10 mL

(1)

• Olive oil

• Rubber stopper

(3)

 

PRE-LAB DISCUSSION

Water is a typical and very common solvent. It dissolves many solids, liquids and gases. If two liquids can be mixed

in any ratio, they are called as miscible liquids. If two liquids can not be mixed, they are named as immiscible liquids.

PROCEDURE

Set-up

Figure

 

Place three test tubes into the test tube rack.

Add 10 mL of water in each test tube with 10 mL graduated cylinder.

Procedure

1.Add 5 mL of ethyl alcohol into the first test tube, 5 mL of olive oil into the second test tube and 5 mL of carbon tetrachloride into the third test tube by using 10 mL graduated cylinder.

2.Close the test tubes with the stoppers and shake them vigorously for several minutes. Place them into the test tube rack.

3.Let the mixtures rest for awhile. Compare the solubility of the liquids in water and record your observations in the Table in “Observations and Data Tables”.

OBSERVATIONS AND DATA TABLES

1.Write your observations in the table below.

Solubility of liquids in water (soluble, Insoluble).

Olive oil

 

Ethyl alcohol

 

Carbon tetrachloride

 

 

 

 

 

........................................................

 

........................................................

 

........................................................

Experiment – 5 Do all liquids dissolve in water?

22

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