25. Qualitative tests have to do with the qualities of substance, these tests identify the presence or absence of a particular substance in a sample. Quantitative tests determine the amount of a specific substance is present in a sample.
26. A confirming test is a test that confirms ions are present.
27.
a) A reference solution is a solution of known components. The purpose of the reference solution is to have a solution where you can compare your other solutions to.
b) The purpose of a distilled water bank is it is a bank known not to contain any ions of interest; therefore, when an ion solution is added to it, there is no reaction. It acts as another comparison solution.
28. If a student tests for iron and observes no water change, then student should not conclude that no iron is present because sometimes when there is a negative test that may either mean there is no ion present, or the ion in present in such low amounts; therefore, it is not certain there is an accurate result.
29.
a) Given an un known mixture, the steps I would follow to classify it as a solution, a suspension, or a colloid would be first mixing the mixture and allowing it to sit for a while. By doing this I can see if particles settle to the bottom of the container. Another way I would classify the mixture would be by using the Tyndall effect.
b) These steps would help me distinguish between the three mixtures by allowing me to see if particles settle to the bottom of the solution after it is mixed and is allowed to settle for a minute. If the particles separate and collect to the bottom, it would show a suspension. If the mixture has a positive Tyndall effect (scattering of light caused by the suspension of particles), then it is a colloid. And if neither of these techniques work, then it is a solution.
30. Failing to follow the instructions "shake before using" on a label of a medicine bottle would be a risk because most of the large particles are on the bottom of the bottle, and are not eventually distributed within the bottle. Therefore, you must shake the bottle to mix the large particles and the liquid together. If you fail to do this you may not be taking the actual medicine part of the mixture, meaning your medication may not work to the best of its ability.
31. It is useful for element symbols to have international acceptance because it allows scientist from all over the world to be able to study the same elements.
32. A model of a solution where water is the solvent and oxygen gas is the solute:
33. No. It is possible to have 100% "chemical free" water because it is impossible to have completely pure water when the atmospheric gases, nitrogen, oxygen, and carbon dioxide, always dissolve in water. Even with the expensive process of distillation, it is still impossible to have 100% "chemical free" water.
34. Water is composed of two hydrogen atoms and one oxygen atom and water's physical property is a liquid. However, the elements that make up water are not a liquid. The physical property of both hydrogen and oxygen is a gas.
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