Bio SPA
SPA is on Monday. Report punctually at the bio SPA lab by 10.45am latest. Topics tested are Nutrition and Nutrition in Humans.
7. You may have seen "Hydrogen Carbonate" indicator. All I can say is that Hydrogen Carbonate is better know as the bicarbonate ion, HCO3- . Taken from http://www.probertencyclopaedia.com/G_BICARBONATE_INDICATOR.HTM. Take the info with a pinch of salt, but I doubt it's too far from the truth. A bicarbonate indicator is a PH indicator sensitive enough to show a colour change as the concentration of the gas carbon dioxide increases. The indicator is used in photosynthesis and respiration experiments to find out whether carbon dioxide is being liberated. The initial red colour changes to yellow as the pH becomes more acidic. Carbon dioxide, even in the concentrations found in exhaled air, will dissolve in the indicator to form a weak solution of carbonic acid, which will lower the pH and therefore give the characteristic colour change.
ADVICE (My two cents worth):
1. Bring all your stationary, a calculator and a curved ruler. Bring these for all SPAs regardless of which science it is.
2. Read through the entire set of instructions and questions before you start any experiments. Don't be too brash and start off immediately. You have an hour for the entire thing. It wouldn't harm to spend 2 to 3 minutes reading the instructions.
3. For graphs, make them as large as possible. Label the axis. Draw a curve only if the shape is very obvious. If it's more like a straight line, draw a best fit line.
4. Memorise all food tests (and learn from the biuret test mistake that most of you made. Add very little biuret solution and observe for changes before you add even more. You may see a faint violet) as well the enzymes in the alimentary canal.
5. Safety first. If you conduct benedict's test, YOU MUST wear goggles. Failure to do so may result in a deduction in marks for skill 1.1.
6. Do not wash or dismantle apparatus until told to do so. The examiner may want to check your apparatus for grading purposes.
7. You may have seen "Hydrogen Carbonate" indicator. All I can say is that Hydrogen Carbonate is better know as the bicarbonate ion, HCO3- . Taken from http://www.probertencyclopaedia.com/G_BICARBONATE_INDICATOR.HTM. Take the info with a pinch of salt, but I doubt it's too far from the truth. A bicarbonate indicator is a PH indicator sensitive enough to show a colour change as the concentration of the gas carbon dioxide increases. The indicator is used in photosynthesis and respiration experiments to find out whether carbon dioxide is being liberated. The initial red colour changes to yellow as the pH becomes more acidic. Carbon dioxide, even in the concentrations found in exhaled air, will dissolve in the indicator to form a weak solution of carbonic acid, which will lower the pH and therefore give the characteristic colour change.
If you've any other tips to share, please feel free to add on. =P Good luck for SPA.
posted by Colin Cheng at
7:18 PM
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