1SBS #25-34 p.52

25. Qualitative tests are tests that identify the presence of absence of a particular substance in a sample, while quantitative tests determine the amount of a specific substance present in a sample.

26. A confirming test is a positive test that confirms that the ion in question is present.

27. The purpose of the reference solution was to have a comparison of one known to contain the sought ion. The purpose of the distilled-water blank was to have a sample that does not contain any ions of interest.

28. No, the student should not conclude that no iron is present because iron dissolves in water and is not visible in water.

29. In a solution, the mixture will have the same composition throughout the entire liquid. In a colloid, the particles will not settle and the mixture will remain cloudy. Finally, in a suspension, the particles will settle. You will know which mixture is which by analyzing each one for each of the characteristics above. 

30. The possible risks in failing to follow the direction “shake before using” on the label of a medicine bottle are that some particles settle to the bottom, and therefore you do not get the full effect of the medicine.

31. It is useful for element symbols to have international acceptance, so that other countries can understand science internationally.

32.

33. No, it is not possible for water to be 100% “chemical free” because the atmospheric gases nitrogen, oxygen, and carbon dioxide will always dissolve in the water to some extent.

34. The physical properties of water are liquids, gases, and solids. The physical properties of hydrogen and oxygen are gases.