Difference between revisions of "GCSE Chemistry Required Practical: Calculating Retention Factors"
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==Key Stage 4== | ==Key Stage 4== | ||
| + | {{#ev:youtube|https://www.youtube.com/watch?v=pnTGNAfu6GE}} | ||
===Meaning=== | ===Meaning=== | ||
| − | Use a [[Chromatography]] [[experiment]] to produce a [[Chromatogram]] and calculate the [[Retention Factor|Retention Factors (R<sub>f</sub>)]] for they [[dye]]s found within different | + | Use a [[Chromatography]] [[experiment]] to produce a [[Chromatogram]] and calculate the [[Retention Factor|Retention Factors (R<sub>f</sub>)]] for they [[dye]]s found within different inks. |
===Method=== | ===Method=== | ||
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#Use a ruler to measure the distance that the [[solvent]] has traveled up the paper. | #Use a ruler to measure the distance that the [[solvent]] has traveled up the paper. | ||
#Use a ruler to measure the distance that the different [[dye]]s have traveled up the paper. | #Use a ruler to measure the distance that the different [[dye]]s have traveled up the paper. | ||
| − | #Use the following equation to find the [[Retention Factor]] for each [[dye]] | + | #Use the following equation to find the [[Retention Factor]] for each [[dye]] |
| − | + | <math>R_f = \frac{d_c}{d_s}</math> | |
:Where: | :Where: | ||
:R<sub>f</sub> = [[Retention Factor]] | :R<sub>f</sub> = [[Retention Factor]] | ||
:d<sub>c</sub> = distance moved by the [[chemical]] | :d<sub>c</sub> = distance moved by the [[chemical]] | ||
:d<sub>s</sub> = distance moved by the [[solvent]] | :d<sub>s</sub> = distance moved by the [[solvent]] | ||
Latest revision as of 19:04, 19 January 2020
Key Stage 4
Meaning
Use a Chromatography experiment to produce a Chromatogram and calculate the Retention Factors (Rf) for they dyes found within different inks.
Method
- Take a piece of chromatography paper of width 6cm and height 10cm.
- Using a ruler draw a line with pencil across the width 2cm up from the end.
- Add a dot of each unknown sample on the pencil line at 1cm intervals.
- Suspend the chromatography paper in a suitable solvent just below the pencil line with most of the paper above the solvent.
- Wait until the solvent stops rising up the paper.
- Remove the paper from the solvent and draw a pencil line at the boundary between the dry and wet areas, then leave the paper to dry completely.
- Use a ruler to measure the distance that the solvent has traveled up the paper.
- Use a ruler to measure the distance that the different dyes have traveled up the paper.
- Use the following equation to find the Retention Factor for each dye
\(R_f = \frac{d_c}{d_s}\)
- Where:
- Rf = Retention Factor
- dc = distance moved by the chemical
- ds = distance moved by the solvent