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How to distinguish NaOH from Ca [OH ]2
1. Introduce carbon dioxide into the liquid to be measured, and Ca (OH)2 will be generated if there is precipitation.
2. Put a small amount of sodium carbonate into the liquid to be measured, and the precipitation is Ca (OH)2.
3. When saturated solution of the same mass is evaporated, Ca (OH)2 is the less precipitated crystal.
4. Add a small amount of sulfuric acid to precipitate Ca (OH)2
1. Introduce carbon dioxide into the liquid to be measured, and Ca (OH)2 will be generated if there is precipitation.
2. Take a small amount of sodium carbonate and put it into the liquid to be measured, and the precipitation is Ca (OH)2.
3. When saturated solution of the same mass is evaporated, Ca (OH)2 is the less precipitated crystal.
4. Add a small amount of sulfuric acid to precipitate Ca (OH)2
How to analyze the problem of excessive and small amount of NaHCO3 reacting with Ca (OH)2 I don't know how it came from. The teacher told us to do it with "set one ", but I still don't understand. I' m a little stupid. Can you tell me more?
In ion equation balancing, a small amount of ion coefficient is 1.
For example, add excess calcium hydroxide to sodium bicarbonate:
A small amount of sodium bicarbonate has a factor of 1 NaHCO3+ Ca (OH)2
Because the reaction of HCO3- with OH- precedes the reaction of CO3(2-) with Ca2+
So only half of the OH- in calcium hydroxide is consumed, and the other half combines with Na+ to form NaOH
That is,1NaHCO3+Ca (OH)2=CaCO3+NaOH+H2O
Change the ion equation to HCO3-+ Ca2++ OH-== CaCO3+ H2O
The reaction between sodium bicarbonate and calcium hydroxide is actually two-step [HCO3-+OH-\Ca2++CO3(2-)], and there is almost no sequence. I say this for your understanding.
The coefficient of small amount of calcium hydroxide is 1NaHCO3+1Ca (OH)2
Because the reaction of HCO3- with OH- precedes the reaction of CO3(2-) with Ca2+
Therefore, the total consumption of OH- in calcium hydroxide requires 2 HCO3-
Ca2++2CO3(2-) remaining 1 CO32-, bound to Na+ to Na2CO3
I.e.2NaHCO3+Ca (OH)2=CaCO3+Na2CO3+2H2O
Change the ion equation to 2HCO3-+Ca2++2OH-=CaCO3+CO3(2-)+2H2
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