Confused with the reaction beetween CaCl2 and NaHCO3?

Question

We have done this lab in our school: http://www.pcds.org/share/sci8/labs/chemrx.htm

This is the reaction I am guessing on right now because during the lab CO2 was formed.

CaCl2 + 2NaHCO3 = CaCO3 + H2O + NaCl + CO2

1) Why do I have 2NaHCO3 when I take the double amount of CaCl2 as NaHCO3

2) We had phenol red in the solution and it turned yellow and foamy when those two reacted, is it an acidly reaction?

3) Why does CaCl2 and PhenolRed together yields heat?

4) After the reaction I filered the solution and found that the NaCl went through the filter and reacted with AgNO3 and formed AgCl and NaNO3.
Is it posible that NaCl can go through the filter?

5) To the "foam" that was left in the filter I added HCl and it fizzed abit. I've heard that CaCO3 does that when it reacts with HCl but what really happens?

Anonymous · Accepted Answer

you havent balanced AT ALL!!!.
4CaCl2 + 6NaHCO3 -------- 4CaCO3 + 2HCl +6NaCl  +2H2O + 2CO2
i dont no what you mean by 1.

2) HCl is hydrochlroic acid so yes it is acidic
3) because its an exothermic reaction
4)yes as NaCl is salt and it dissolves
5) no idea

drbillmacmo · Answer

1.  
CaCl2  +  2NaHCO3  ==>  CaCO3  +  2NaCl  +  H2O  +  CO2
Check your balanced equation
2.
Your reaction is a neutralizion reaction.  CaCl2 is an acid salt and NaHCO3 is basic. 
A preliminary product was H2CO3, carbonic acid.  That turned the phenol red yellow.  The foaming came from the immediate decomposition of H2CO3 to H2O _ CO2.
3.
Phenol Red acts as a buffering solution.  The CaCl2 is neutralizing the phenol red.  Neutralization reactions are exothermic.
4.  Yes.  NaCl in solution is Na+ and CL- ions aqueous.  Your filter could not capture anything the size of an ion.
5.  
CaCO3  +  2HCl  ==>  CaCl2  +  H20  +  CO2
The CO2, once again, created bubbles.

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Confused with the reaction beetween CaCl2 and NaHCO3?

2 Answers