SUPER URGENT - for Thursday - fertiliser experiment. (1 Viewer)

[Mr_Kap]

I have a report due tomorrow so any help is appreciated greatly.

The report is on finding sulfate content of lawn fertiliser experiment...and i have 2 question:

1) What are the assumptions made that the experiments validity is dependant on?

and 2) what is the difference between accuracy, and validity in this experiment?

 

[Kaido]

1. Complete precipitation, complete dryness, no particles accidentally fell through the filter paper
2. Accuracy - results of the experiment (in this case, a titration) are compared with other groups to show they are similar
Validity - correct method able to satisfy the aim of the experiment

 

[Mr_Kap]

1. Complete precipitation, complete dryness, no particles accidentally fell through the filter paper
2. Accuracy - results of the experiment (in this case, a titration) are compared with other groups to show they are similar
Validity - correct method able to satisfy the aim of the experiment

We didn't perform a titration for this....and i thought that comparing to other groups was reliability?

 

[InteGrand]

We didn't perform a titration for this....and i thought that comparing to other groups was reliability?

Yeah, reliability is comparing with other groups.

Accuracy is based on how far your obtained value differs from the theoretical value, which you would probably only know if you were told this (e.g. if it was known beforehand what the concentration of sulfate in the lawn fertiliser was).

 

[Crisium]

A few general tips (because I haven't started Chemical Monitoring and Management yet):

Variables:

• Independent Variable: The variable that is changed during the experiment.

• Dependent Variable: The variable which is specifically measured.

• Controlled Variable: The variable that is kept constant throughout the experiment.

• Graphing With Variables:

- Independent Variable: Horizontal Axis (i.e. X-Axis)

- Dependent Variable: Vertical Axis (i.e. Y-Axis)

Risk Analysis:

• Comment on the risks associated with using the equipment and chemicals involved in the investigation, and explain why they pose a risk.

• Provide necessary precautions for the experiment so as to minimise or eliminate the risk.

Discussion:

• Accuracy:

- The experimental data should be compared to the accepted values.

- The instruments used in the experiment affect the accuracy.

- Comment on the possible sources of error.

• Reliability:

- The experiment should be repeated a minimum of 5 times in conjunction with an examination of a consistency in results.

- The experimental data should be compared to others performing the same experiment under the same conditions.

• Validity:

- The investigation should apply accepted laws and mathematical relationships.

- All variables should be controlled, barring the dependent and independent variables.

- The type of analysis of the experimental data should be appropriate.

- The experimental method should be testing the aim whilst being scientifically valid.

Definitions:

• Inference: A logical explanation for a problem that takes into account all the known facts and observations.

• Generalisation: A broad statement which explains a problem taking into account all the known facts and observations.

• Transcription Error: Accidentally recording the incorrect value obtained from an electronic device.

• Parallax Error: Not reading the measuring scale properly.

• Interpolate: Find data in between the known range of values.

• Extrapolate: Find data outside the known range of values.

 

[Mr_Kap]

thx so much guys!!!!!