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AQA GCSE Chapter 12
AQA GCSE Chapter 12 analysis DOUBLE ONLY
| Question | Answer |
|---|---|
| Describe how to carry out a chromatography experiment | draw a start line in PENCIL, ABOVE the water level; place a dot of your mixture and a dot for references on start line; place the paper in beaker WITH A LID; remove paper before the solvent reaches the top of the paper; draw a line on the solvent FRONT |
| Why does the start line need to be drawn in PENCIL? | if the line was drawn in ink, the ink could rise with the solvent as well as your mixture |
| Why does the start line need to be drawn ABOVE the water level? | If the line was below, the dot from the mixture would dissolve into the water instead of rising up the paper |
| Why do we place a lid on top of the beaker? | to prevent teh solvent from evaporating |
| Looking at a chromatogram, how would you know if a chemical is a mixture? | There would be more than one dot above the start line |
| Looking at a chromatogram, how would you know if HOW MANY different chemicals were in a mixture? | COUNT the dots above the start line |
| Looking at a chromatogram, how would you know if how many different chemicals were in a mixture? | COMPARE the HEIGHT of the dots above the start line of the mixture to the HEIGHT of reference/pure chemicals; if two dots are at the same height, then they are the same chemical |
| Looking at a chromatogram, how would you know which chemical is the most soluble? | the most soluble chemical rises the furthest; has the biggest Rf |
| Explain why a chemical rise up the paper | A chemical rises up the paper when it forms STRONGER bond with the mobile phase (solvent) than the bond it forms with the stationary phase (paper) |
| What is the stationary phase? | the paper |
| What is the mobile phase? | the solvent |
| How do you work out the Rf for a given dot? | measure the distance from the start line to the MIDDLE of the dot; measure the distance from the start line to the solvent front; divide the start-to-dot by start-to-front |
| Looking at a chromatogram, how would you know if how many different chemicals were in a mixture? | COMPARE the Rf of the dots above the start line of the mixture to the Rf of reference/pure chemicals; if two dots are at the same Rf, then they are the same chemical |
| What is the chemical test for oxygen gas? | A GLOWING splint RELIGHTS |
| What is the chemical test for hydrogen gas? | A LIT splint makes a SQUEAKY pop |
| What is the chemical test for carbon dioxide gas? | when BUBBLED through LIMEWATER, the limewater turns cloudy |
| (CHALLENGE) why is it not enough to identify carbon dioxide gas to say "carbon dioxide turns off a flame"? | Because nitrogen gas also turns off a flame |
Created by:
ursulinechem2
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