ISBS #25 - 34 p.50

25) There are many differences between qualitative and quantitative tests. Qualitative tests are tests that identify the presence or absence of a particular substance in a sample. This has to do with the appearance, such as color, of a substance. On the other hand, quantitative tests determine the amount of a specific substance present in a sample.

26) A confirming test is a labratory test that gives a positive result if a particular chemical species is present

27) In the water testing investigation, the purpose of (a) the reference solution, was to be used as a comparison for other tests since it contained the sought ion, and  (b) the distilled water blank didn't contain any ions, so it could also be used as a comparison against the unknown solution.

28) Using the procedure outlined in the water testing investigation, a student tests a sample of groundwater for iron and observes no color change. The student should not conclude that no iron was present because the student also needs to check for a participate before making a conclution.

29) Given an unknown mixture, the steps you would use to classify a solution, a suspension, or a colloid are as follows. For a suspension, you could use filtration, and if a filtrate is left after the procedure, then you could likely conclude that the mixture is a suspension. For a colloid, if the mixtutre appears cloudy, you could shine a light through it to see if there are small solid partilces that are in the substance. If so, it supports the theory that the mixture is a colloid. If both of these procedures tested negative, then you can likely conclude that the mixture is a solution becase the solute had dissolved in the solvent.

30) Possible risks in failing to follow the direction, "shake before using" on the label of a medicine bottle, could be not getting the full dose because you are not reciving all parts of the substance.

31) It is useful for element symbols to have an international appearance because people all over the world can use a universal chemisty language.

32) The drawing shows oxygen gas dissolving in water. The blue cubes represent ice cubes because gas molecules dissolve more easily under cold temperatures.

33) It is not possible for water to be 100% chemical free because the atmosphereic gasses nitrogen, oxygen and carbon dioxide will always disolve in the water to some extent.

34) The physical properties of water are due to the elements that compose the compound. The hydrogen side of the water molecule has a slight positive charge while the oxygen side of the molecule has a slightly negative charge. This molecular polarity causes water to be a powerful solvent and to have strong surface tension.