Halogens: Behavior in Water & Hexane, Interactions with Halides, and Silver Salts | Exams Chemistry

PROPERTIES OF HALOGENS

Procedure:

1. Examine the containers of the elements. Note the color and the physical state of each of

the elements at room temperature. Record results in the table listed in #1 on the data

sheet.

2. Add a small amount of NaCl (equivalent to one shake of a salt shaker) to a 10 X 75 mm

test tube. Now add 15 drops of distilled water using your wash bottle. Mix the contents

of the test tube by flicking the test tube. Does the NaCl dissolve? To a second test tube,

add the same amount of NaCl and instead of water, add 15 drops of hexane. Does the

NaCl dissolve in the hexane? Now add 15 drops of water to the second test tube. Notice

that the water is at the bottom of the test tube and that the hexane layer is at the top. Try

to get the NaCl to dissolve. Do you think the NaCl dissolved in the water layer or in the

hexane layer? You can do this same experiment at home using table salt, NaCl, and

cooking oil instead of hexane. NaCl dissolved in water to form chloride ions or Cl-.

Polar liquids like water dissolve ionic substances. Non-polar liquids such as hexane are

very poor at dissolving ionic salts. Test NaBr and NaI in water and in hexane in a similar

manner. Record results in the table listed in #2 on the data sheet.

3. Add 15 drops of iodine water (I2 dissolved in water) to a 13 X 100 mm test tube. Note

the color of this solution on the data sheet. Now add 10 drops of hexane to the test tube.

Stopper the tube (corks are available at the stockroom window) and shake it vigorously.

Record the color of the hexane layer on your data sheet. From the intensity of the color

in each layer, in which solvent is the halogen more soluble? Record results in the table

listed in #3 on the data sheet.

a.) Repeat the above procedure using bromine water. Notice that both iodine, I2 and

bromine, Br2, color the hexane layer.

b.) Repeat the procedure using chlorine water. Chemically, chlorine, Cl2, is very

similar to the other halogens. However, chlorine does not have very much color

in hexane.

4. Reactions between Halogens and Halide Ions. Record results for all parts in the table

listed in #4 on the data sheet.

a.) Into a 13 X 100 mm test tube add 10 drops of 0.2 M NaI solution (note: 0.2 M is

a measure of concentration; be sure you use the correct bottle and 10 drops of

hexane. In a second 13 x 100 mm test tube, add 10 drops of 0.2 M NaBr and 10

drops of hexane. Note the color of the hexane layer on your data sheet. Why is

there no color in the hexane layer? Are we using halogens or halide ions in this

part of the experiment?

Now add 20 drops of chlorine water, Cl2, to each of the test tubes. Stopper

the tubes and shake them for about 1 minute. Record the color of the hexane

layer. Why is the hexane colored? We added chlorine water, but Cl2 is colorless

in hexane as we observed in part 3 of the procedure. The Br- and I- ions were also

colorless in the beginning before we added the chlorine water. Look at the test

tube with NaI in it. Compare the color of the hexane layer to the color of the

hexane Layer for iodine water, I2, in part 3 of the procedure. A chemical reaction

has taken place. Iodide ion has been converted to iodine. The following equation

illustrates this reaction: Cl2 + 2I1- → I2 + 2Cl1-. Chlorine has been converted to

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PROPERTIES OF HALOGENS

Procedure:

Examine the containers of the elements. Note the color and the physical state of each of the elements at room temperature. Record results in the table listed in #1 on the data sheet.
Add a small amount of NaCl (equivalent to one shake of a salt shaker) to a 10 X 75 mm test tube. Now add 15 drops of distilled water using your wash bottle. Mix the contents of the test tube by flicking the test tube. Does the NaCl dissolve? To a second test tube, add the same amount of NaCl and instead of water, add 15 drops of hexane. Does the NaCl dissolve in the hexane? Now add 15 drops of water to the second test tube. Notice that the water is at the bottom of the test tube and that the hexane layer is at the top. Try to get the NaCl to dissolve. Do you think the NaCl dissolved in the water layer or in the hexane layer? You can do this same experiment at home using table salt, NaCl, and cooking oil instead of hexane. NaCl dissolved in water to form chloride ions or Cl-. Polar liquids like water dissolve ionic substances. Non-polar liquids such as hexane are very poor at dissolving ionic salts. Test NaBr and NaI in water and in hexane in a similar manner. Record results in the table listed in #2 on the data sheet.
Add 15 drops of iodine water (I 2 dissolved in water) to a 13 X 100 mm test tube. Note the color of this solution on the data sheet. Now add 10 drops of hexane to the test tube. Stopper the tube (corks are available at the stockroom window) and shake it vigorously. Record the color of the hexane layer on your data sheet. From the intensity of the color in each layer, in which solvent is the halogen more soluble? Record results in the table listed in #3 on the data sheet. a.) Repeat the above procedure using bromine water. Notice that both iodine, I 2 and bromine, Br 2 , color the hexane layer. b.) Repeat the procedure using chlorine water. Chemically, chlorine, Cl 2 , is very similar to the other halogens. However, chlorine does not have very much color in hexane.
Reactions between Halogens and Halide Ions. Record results for all parts in the table listed in #4 on the data sheet. a.) Into a 13 X 100 mm test tube add 10 drops of 0.2 M NaI solution (note: 0.2 M is a measure of concentration; be sure you use the correct bottle and 10 drops of hexane. In a second 13 x 100 mm test tube, add 10 drops of 0.2 M NaBr and 10 drops of hexane. Note the color of the hexane layer on your data sheet. Why is there no color in the hexane layer? Are we using halogens or halide ions in this part of the experiment? Now add 20 drops of chlorine water, Cl 2 , to each of the test tubes. Stopper the tubes and shake them for about 1 minute. Record the color of the hexane layer. Why is the hexane colored? We added chlorine water, but Cl 2 is colorless in hexane as we observed in part 3 of the procedure. The Br-^ and I-^ ions were also colorless in the beginning before we added the chlorine water. Look at the test tube with NaI in it. Compare the color of the hexane layer to the color of the hexane Layer for iodine water, I 2 , in part 3 of the procedure. A chemical reaction has taken place. Iodide ion has been converted to iodine. The following equation illustrates this reaction: Cl 2 + 2I1-^ → I 2 + 2Cl1-. Chlorine has been converted to

chloride ion and iodide ion has been converted to iodine. What do you think happened in the test tube with NaBr? b.) Into a 13 X 100 mm test tube add 10 drops of 0.2 M NaCl solution and 10 drops of hexane. In a second tube, add 10 drops of 0.2 M NaI and 10 drops of hexane. What is the color of the hexane layer? Now add 10 drops of bromine water (Br 2 ) to each of the test tubes. Stopper and shake the tubes for a few seconds, then allow to settle for about 1 minute. What is the color of the hexane layer? What is present in the hexane layer to give this color? If a reaction occurred, what would be the equation for the single displacement reaction? Did a reaction occur? c.) Into a 13 X 100 mm test tube add 10 drops of 0.2 M NaCl solution and 10 drops of hexane. In a second tube, add 10 drops of 0.2 M NaBr solution and 10 drops of hexane. What is the color of the hexane layer? Now add 20 drops of iodine water (I 2 ) to each test tube. Stopper, and shake each tube for a few seconds, then let settle for about one minute. Write the equation for the single displacement reaction that might occur. What is the color of the hexane layer? What is present in the hexane layer to give this color? Did a reaction occur?

Silver Halide Salts. Record results in the table listed in #5 on the data sheet. a.) Into a 13 X 100 mm test tube, add 5 drops of 0.2 M NaCl. Into a second test tube, add 5 drops of 0.2 M NaBr. Into a third tube, add 5 drops of 0.2 M NaI. Now add 5 drops of 0.20 M AgN0 3 (silver nitrate) to each test tube. Shake each tube to make sure a reaction takes place. Record the color of the silver halide salts that have formed. b.) Solubility tests - i. To each test tube, add 20 drops of dilute (5-7 M) ammonium hydroxide (ammonia solution) and shake the contents of the tube. One of the silver salts should dissolve. ii. Now add 20 drops of concentrated ammonium hydroxide to the two test tubes which still have precipitates. Do this addition under a fume hood. Stopper and shake the test tubes. Again, only one of the silver salts should dissolve. iii. Add 20 more drops of concentrated ammonium hydroxide to the test tube that still has a precipitate. The precipitate will probably still not dissolve.
Check out an unknown salt (NaCl, NaBr, or NaI) from the stockroom window. If your unknown is a solid, add 20 mL of water to it and stir or shake thoroughly to dissolve the salt. If the unknown is a liquid, use as is. Record results in the blanks listed in #6 on the data sheet. a.) To a 13 X 100 mm clean test tube, add 10 drops of the unknown halide solution. Now add 5 drops of 0.2 M AgNO 3 solution. Record the color of the precipitate. b.) Check the solubility of the precipitate in NH 3 solution as in part 5. c.) To a 13 X 100 mm clean test tube add 10 drops of the unknown halide solution, 10 drops of hexane, and 10 drops of chlorine water. The color of the hexane layer should indicate whether Cl-,^ Br-,^ or I-^ was in the unknown solution. Check your results with part 3 of this experiment. d.) Record your unknown number and report which unknown salt was checked out from the stockroom window. Return the 13 X 100 test tube that contained your unknown salt to the stockroom window.

Reactions between Halogens and Halide Ions Halogen Halide Ion Cl 2 I- Br- Chlorine Water Color of hexane layer before addition of Cl 2 Write equation for possible reaction. Color of hexane layer after addition of Cl 2 Is there a reaction? Cl- I- Br 2 Bromine Water Color of hexane layer before addition of Br 2 Write equation for possible reaction Color of hexane layer after addition of Br 2 Is there a reaction?

Halogen Halide Ion I 2 Cl- Br- Iodine Water Color of hexane layer before addition of I 2 Write equation for possible reaction. Color of hexane layer after addition of I 2 Is there a reaction?

Solubility of Silver Salts AgCl AgBr AgI Color of ppt Solubility in NH 3 solution*

Key: S - Soluble in dilute NH 3 ; SS - Soluble in concentrated NH 3 ; IS - Insoluble in NH 3 solution of any concentration
1. Analysis of Unknown Halide Unknown Number______________ Color of silver halide ___ Solubility of silver halide__________ Color of hexane layer after reaction with chlorine water___________ Unknown is_____________

Halogens: Behavior in Water & Hexane, Interactions with Halides, and Silver Salts, Exams of Chemistry

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PROPERTIES OF HALOGENS