Question

I just have a question about interpreting my Lab Instructions. Chemistry/Math Related. Its about graphing Ratios.

Answer 1

Here's the instructions:
3. Use a spreadsheet to determine the ratio of ethanol area count to 1-propanol area count for each standard.
4. Use the format established in Preliminary Exercise lab to perform linear regression on the data and obtain the slope (m) and intercept (b).
5. Use the % ethanol as x-values and area ratios of ethanol to 1-propanol are y-values.

6. Construct a calibration plot for visual presentation. Next, enter data for the three samples and determine ethanol/1-propanol peak area ratios. For each sample, substitute sample area ratio for Y in the Y= mx + b equation, where m is the slope and b is the intercept of the calibration plot above. Solve the equation for x to determine % ethanol in each prepared sample.

Answer 2

do you know how to enter the data on excel?
You should have one column (say A) devoted to ethanol area and another one (B) to 1-propanol (label these columns in cells A1, B1.
Then in another column C type the formula for ratio: =A2/B2
This will automatically calculate the ratio in column C and you can click and drag the formula down to cover all cells in Column C.

Answer 3

@NotTim
It might help more if you can specify which part of the instruction you're having difficulties with.
If you are given these instructions, there is an expectation that you know how to do at least some of the items, if not all.

Answer 4

My problem is with ratios. How would one plot that on a graph? I was thinking just dividing the 2 values. Would that be valid?

Answer 5

Short answer: ratios can be determined using the method proposed by @mww above.
Long answer:
To know what is actually expected, you need to define/describe all variables.
It is not clear, but it seems that you have a data set where you have 3 variables, something like:
%ethanol, ethanol area, 1-propanol area.
which would be reduced to two variables by taking the ratio of the two latter variables:
X=%ethanol, Y=ratio of ethanol/1-propanol areas.

As for the regression, it is not clear to me what the variables are. Perhaps it is %ethanol vs ratio, perhaps something else. The `format established in Preliminary Exercise lab` should elucidate this question.

Hope the above makes sense to you.

Answer 6

So ratio can be determined by dividing the two values correct? It doesn't have to be in the form Number:Number?