prac assesment report

[bluesoleli]

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I need some help on how to do my practical assesment report for EES. It's a report for soil analysis and testing for salts, pH and organic content.
I'm confused about the section which asks me about the independent, dependent variable and constant. For the independent I put down the soil environment, dependent I put down the storage environement and handling process and for constant i had down the fact that the incubator was used to keep some samples at a constant temperature to dry it out.... i'm not sure if i've done it correctly.

My next task is to write a discussion and I don't even know where to start or what to write.... any help would be good.

Thanks.

[henry08]

The independent variable is the period of time the soil was in the incubator for, or the temperature in the incubator. The dependent variable is what occurs (it is a relationship of the independent variable, i.e. if x = a, then y = b, or what you observe etc), i.e. the amount of a certain salt left in the soil sample after it has been incubated. Your constant would be the time period each sample was placed in the incubator for, and the temperature of the incubator. I'm not really sure of the experiment you are trying to do, but I'm fairly sure that you have the wrong dependent/independent/constant.

Why are you using an incubator?
To test pH, sprinke some Barium sulfate powder (which is white) onto a soil sample, and mix it in. Then add a couple of drops of Universal Indicator and you can easily determine the pH.
To test organic content, place the soil sample in a container with small ventilation hoels and let it dry out. Then weigh the soils mass. Now burn the soil and all the organic matter will burn away. Reweigh teh soil. The mass lost was the organic matter.
To test for salts (such as Ca, Ba etc) there are simple tests involving a few simple chemicals and from the esulting color change you can determine if that salt is present (process of elimination steps). Let me know if you want mroe info or help.