The rate of photosynthesis

[zainub94]

Im doing a coursework, im at GCSE level. This coursework is late:-( and this doesnt really need to be included in it, but I was thinking about it. The investigation is simple: How does light intensity affect the rate of photosynthesis? We used the classic method, of pondweed in a beaker of water, with a lamp shining at it, from varied distances for a minute at each. To make sure no other factors affected the rate, we took soem measures. One was to add a spatula full of sodium hydrogen carbonate, to prevent carbon dioxide being a limiting factor to the rate of photosynthesis. what i wanted to include in my coursework was exactly how and what reacts, releasing the carbon dioxide. Sorry if this is a very low level question, its just that, I havent even finished secondary school yet, almost at college, jus need to sort these GCSE's. Id really appreciate some help. Thanks.

[Bluenoise]

Im doing a coursework, im at GCSE level. This coursework is late:-( and this doesnt really need to be included in it, but I was thinking about it. The investigation is simple: How does light intensity affect the rate of photosynthesis? We used the classic method, of pondweed in a beaker of water, with a lamp shining at it, from varied distances for a minute at each. To make sure no other factors affected the rate, we took soem measures. One was to add a spatula full of sodium hydrogen carbonate, to prevent carbon dioxide being a limiting factor to the rate of photosynthesis. what i wanted to include in my coursework was exactly how and what reacts, releasing the carbon dioxide. Sorry if this is a very low level question, its just that, I havent even finished secondary school yet, almost at college, jus need to sort these GCSE's. Id really appreciate some help. Thanks.

 

This is definatley not a low level question. Much higher level than most of what's asked around here I'd say.

 

Carbon dioxide actually has very low solubility in Water. However it can react with water to produce carbonic acid. Most of it is in an equalibrium between the two.

 

Now if you replace one of the hydrogen atoms in carbonic acid with sodium you get Sodium hydrogen carbonate aka baking soda.

This is why you have to store sodium hydroxide in an air tight container, CO2 will disolve in it convert to carbonic acid and react with the sodium hydroxide producing baking soda.

 

Now to get the reverse to happen all you need to do is supply more hydrogen, by lets say an acid. So any acid in the solution will react with the baking soda, which gives carbonic acid. Now as carbonic acid goes up it will equilibrate with Carbon dioxide raising the CO2 concentration in the liquid. Which saturates the liquid most often as CO2 has very low solubility.

 

Now the acid comes from metabolism of the plant (I believe).

 

So acid from plant + baking soda = more CO2

 

IE HNaCO3 + acid = CO2 H2O + salt.

[zainub94]

Thanks very, very much, thats was very useful. It definitely took me a while to fully undertsand it due to the fact Ive never been through that before at school, but I finally did, n I find it very useful. Thanks for your time n help, much appreciated.

[arron]

Take a look at the following article on Photosynthesis, helped me with my coursework hugely Photosynthesis