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# What is the pricinple behind 1.8g NaHCO3 per litter when CO2 is 5%?

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### #1 AllenChiu

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Posted 07 May 2010 - 05:09 AM

When the partial pressure of CO2 is 5%,you should add 1.8g NaHCO3 to 1L DMEM (high glucose GIBCO）,
when it's 10%,you should add 3.7g NaHCO3.
then what is the pricinple/theory/formula behind this?
How to convert?
I added 3.7g NaHCO3 per litter when CO2 is 5%,what is the harm?
Does it have anything to do with the relatively fast change of the color to yellow?

### #2 Inmost sun

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Posted 09 May 2010 - 12:54 PM

AllenChiu, on May 7 2010, 01:09 PM, said:

When the partial pressure of CO2 is 5%,you should add 1.8g NaHCO3 to 1L DMEM (high glucose GIBCO）,
when it's 10%,you should add 3.7g NaHCO3.
then what is the pricinple/theory/formula behind this?
How to convert?
I added 3.7g NaHCO3 per litter when CO2 is 5%,what is the harm?
Does it have anything to do with the relatively fast change of the color to yellow?

NaHCO3 + H2O = Na+ + H2CO3 + OH- = CO2 + H2O + Na+ + OH-

or

NaHCO3 + 2H2O +CO2 = Na+ + 2H2CO3 +OH- = 2CO2 + 2H2O +Na+ + OH-

NaHCO3 and CO2 will be in balance, regard the K for NaHCO3, and K for H2CO3; to calculate the correct percentage of CO2 you also need the incubator volume

### #3 AllenChiu

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Posted 10 May 2010 - 07:58 AM

Inmost sun, on May 10 2010, 04:54 AM, said:

AllenChiu, on May 7 2010, 01:09 PM, said:

When the partial pressure of CO2 is 5%,you should add 1.8g NaHCO3 to 1L DMEM (high glucose GIBCO）,
when it's 10%,you should add 3.7g NaHCO3.
then what is the pricinple/theory/formula behind this?
How to convert?
I added 3.7g NaHCO3 per litter when CO2 is 5%,what is the harm?
Does it have anything to do with the relatively fast change of the color to yellow?

NaHCO3 + H2O = Na+ + H2CO3 + OH- = CO2 + H2O + Na+ + OH-

or

NaHCO3 + 2H2O +CO2 = Na+ + 2H2CO3 +OH- = 2CO2 + 2H2O +Na+ + OH-

NaHCO3 and CO2 will be in balance, regard the K for NaHCO3, and K for H2CO3; to calculate the correct percentage of CO2 you also need the incubator volume
great，Thank you！

### #4 hobglobin

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Posted 10 May 2010 - 08:23 AM

Inmost sun, on May 10 2010, 04:54 AM, said:

AllenChiu, on May 7 2010, 01:09 PM, said:

When the partial pressure of CO2 is 5%,you should add 1.8g NaHCO3 to 1L DMEM (high glucose GIBCO）,
when it's 10%,you should add 3.7g NaHCO3.
then what is the pricinple/theory/formula behind this?
How to convert?
I added 3.7g NaHCO3 per litter when CO2 is 5%,what is the harm?
Does it have anything to do with the relatively fast change of the color to yellow?

NaHCO3 + H2O = Na+ + H2CO3 + OH- = CO2 + H2O + Na+ + OH-

or

NaHCO3 + 2H2O +CO2 = Na+ + 2H2CO3 +OH- = 2CO2 + 2H2O +Na+ + OH-

NaHCO3 and CO2 will be in balance, regard the K for NaHCO3, and K for H2CO3; to calculate the correct percentage of CO2 you also need the incubator volume

But temperature (and presumable pressure) should also be considered, as it influences the balance too a lot...i.e. the specification should be completed with a fixed temperature such as 20°C, or STP.

Edited by hobglobin, 10 May 2010 - 08:57 AM.

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