Double-Replacement Reactions



Background: Research and report information on double replacement reactions here. Check pages in your textbook for a general discussion of double-replacement reactions. Use the internet.

Go to the following site, find and explore the examples of double replacement reactions: chemical reaction examples

Give an example of a double replacement reaction not being done in this class. Also include information about solutions , precipitates, filtration methods , ions , Lead Nitrate and Potassium Iodide. Focus on the potential health hazards of each compound above.

Problem: Identify a clue that shows that a double replacement reaction produces new products.

Hypothesis: Write a hypothesis for this lab.

Materials: (per group)

safety goggles electronic balance 2 250-ml beakers
weighing paper lead nitrate potassium iodide
stirring rod graduated cylinder apron
filter paper funnel

Procedure:

  1. Put on safety goggles and your apron.
  2. Place a piece of weighing paper on the balance and note its mass. Rezero your balance (tare). Measure out 1.5g of lead nitrate and place it in one of the beakers. Discard the paper.
  3. Add 25 ml of distilled water to the beaker and stir thoroughly to make sure that all the solid has dissolved. Rinse off the stirring rod and wipe it dry. Label the beaker Lead nitrate solution.
  4. Repeat steps 2 and 3 using potassium iodide. Label the beaker Potassium iodide solution.
  5. Pour the solution from one beaker into the other beaker and observe the results. Stir with the stirring rod and observe.
  6. Set up a filtration system using the filter paper, funnel and a small beaker.
    Folding a piece of filter paper for insertion into a conical filter consists of a simple set of steps shown here in the six photographs below. From left to right and top to bottom, one first folds the round piece of filter paper in half and creases it.Then it is folded again and creased to produce a quarter circle. One outer layer of paper is separated from the other three (not two and two!) and the opening made wider by squeezing slightly together at the creases. The conical shaped piece of filter paper is placed into a glass or plastic funnel and wetted slightly with distilled water from your wash bottle:

  7. Pour the solution into the filter paper and let the solution filter through. Examine the separated products. Describe each product in the data section.
  8. To dispose of your product, put the filtered liquid into the waste container indicated by your teacher. Do not spill the product down the sink. Rinse the beaker once with tap water and dispose of this material in the waste container. Thoroughly wash the beakers and stirring rod with soap and water. Place the product in the filter paper in the indicated trash can.

Data/Observations: Use the following questions to help you focus on the observations.

  1. What did you observe when you mixed the lead nitrate with water?
  2. What did you observe when you mixed the potassium iodide with water?
  3. What did you observe when you mixed the two solutions together?
  4. Did stirring the combination of the two solutions result in any change? Explain.

Analysis: Use the following questions to help you analize your data.

  1. What ions were present in the lead nitrate solution?
  2. What ions were present in the potassium iodide solution?
  3. Write an equation for the reaction that took place.
  4. A double-replacement reaction is also called an ion-exchange reaction. Describe the exchange of ions that occurred in this investigation.
  5. What must always be one of the products of a double-replacement reaction? ( think States of Matter)
  6. What must the other product(s) always be?
  7. Describe what happened when the product you obtained in this reaction was filtered through a filtering apparatus.

Conclusion: Summarize your answer to the problem question using the data you collected.

Going Further

  • Identify each of the following chemical equations as representing a synthesis, decomposition, single-replacement, or double-replacement reaction. Write a balanced equation for each reaction.
    1. Carbon monoxide -> Carbon + Oxygen
      • CO --> C + O2


    2. Sodium + Water -> Sodium hydroxide + Hydrogen gas
      • Na + H2O --> NaOH + H2


    3. Aluminum sulfate + Barium chloride -> Aluminum chloride + Barium sulfate
      • Al2(SO4)3 + BaCl2 --> AlCl3 + BaSO4


    4. Aluminum + Chlorine -> Aluminum chloride
      • Al + Cl2 --> AlCl3


    5. Sodium carbonate + Calcium hydroxide -> Sodium hydroxide + Calcium carbonate
      • Na2CO3 + Ca(OH)2 --> NaOH + CaCO3





    Go to the following site and take the review quiz. Double Replacement

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    This page was last updated on 08.15.08