Investigating the Chemical Properties of Four Liquids

Pairs are preferred but you may work alone if you wish. Groups of three or more are not permitted.

The Report

One report per person. Use standard headings for lab reports. Include in your report data Table 1 and the answers to all questions using complete sentences.

The Problem:

Suppose there are four colourless liquids in front of you. How do you tell whether they are the same or different? In this experiment you will do some simple chemical tests to determine whether any of these four liquids have the same chemical properties.

CAUTION: Some of these liquids are very corrosive and can react with your clothing or your skin. Do not be afraid of them, but do follow safe procedures. If any splash on you, let your teacher know right away.

Reagents and Equipment

red litmus paper

blue litmus paper

mossy zinc metal

potassium iodide powder

cobalt chloride paper

aluminum metal foil

4 colourless liquids (labeled A, B, C, D)

spot plate

Data

Copy and complete the following table:

Table 1: Observations

Liquid A / Liquid B / Liquid C / Liquid D
red litmus paper
blue litmus paper
cobalt(II) chloride paper
mossy zinc metal
aluminum metal foil
potassium iodide powder /

Procedure

  1. Get a spot plate. Place liquid A into each of 6 wells, filling each well about half full. This should form a column of wells down the left side of the spot plate. Repeat with the other three liquids in each of the subsequent columns. Ultimately there will be a grid of four columns and six rows. You may want to label them.
  1. By referring back to Table 1 in the data section, perform the 6 different tests on each liquid. Use reagents sparingly. For example, one piece of litmus paper can be cut up into at least 4 smaller pieces. For the potassium iodide powder, add only a few crystals to each well.
  1. Record your observations in a data table. Be sure to say the colour or the appearance. If, for example, a red test paper stays red, don’t write “no change”, write “red”. In some cases, bubbles will form.

Questions

Refer to page 44 of Hebden, and read the definitions on that page. Answer the following in complete sentences:

Responses written in the form of sentence fragments or point form will not be marked.

  1. Define the term chemical property.
  1. State the difference between extensive and intensive properties and give one example of each.
  1. Suppose two identical looking substances are tested in ten different chemical tests, and all the results of the tests are the same for both substances. Is it possible to conclude that the two substances must be the same chemical? Explain why or why not.
  1. Using the data from your experiment, is it possible to conclude that any two of these unknowns are actually the same? Explain why or why not.