Page 238 - Chemistry ICSE Class IX
P. 238
226 ICSE Chemistry – 9
Procedure
Proceed through the steps given below:
y Take the two given samples in separate beakers, and label them as A and B.
y Take about 2 mL of each sample in separate test tubes. Label them as A and B.
y Add a few drops of soap solution in each, and shake both the solutions. Note if the solutions give lather
or not.
y Now, add washing soda solution dropwise in both the samples of water in the two beakers A and B.
Stir both the solutions.
y Filter both the solutions separately and collect the filtrate in different test tubes.
y Add 0.5 mL of soap solution to each of the test tubes, and shake these vigorously.
y Observe if lather is formed or not.
y Record your observations.
Observations
Before adding washing soda solution #HVGT CFFKPI YCUJKPI UQFC CPF ſNVTCVKQP
5CORNG # 6GUV VWDG # 5CORNG $ 6GUV VWDG $ 5CORNG # 6GUV VWDG # 5CORNG $ 6GUV VWDG $
Does not give lather Does not give lather Gives lather with soap Gives lather with soap
with soap solution. with soap solution. solution. solution.
Forms curdy precipitate Forms curdy precipitate No curdy precipitate No curdy precipitate
with soap solution. with soap solution. formed with soap formed with soap
solution. solution.
Results
The hardness of both the samples of water is removed by treating with washing soda.
Conclusions
Both, temporary hardness and permanent hardness in water can be removed by adding washing soda.
Reactions
y (QT VGORQTCT[ JCTFPGUU
Ca(HCO ) + Na CO (aq) o CaCO (s)p + 2NaHCO (aq)
3 2
3
3
2
3
calcium bicarbonate washing soda white precipitate sodium hydrogencarbonate
(causes temporary hardness)
y (QT RGTOCPGPV JCTFPGUU
CaSO (aq) + Na CO (aq) o CaCO (s)p + Na SO (aq)
4
3
2
4
3
2
calcium sulphate white precipitate sodium sulphate
(causes permanent hardness)
