Qualitative Analysis | Test for Cations

[@mercyheneson6951]

I guess you should have added the observations of each test because people actually find difficulties in differentiating some of the observation like the white chalky ppt,white gel ppt and the coloured ppt.

[@boofang10]

PERFECT Mr Jansen !!! And I like the catchy tunes to go with it !!! Definitely going to be helpful in my Online Class today for my F5 students as they prepare for their SPM Practical Exams this Tuesday, 15th Feb 2022 !!

[@MrJansenTan]

Thank you! Happy to hear that it is helpful :)

[@mim.h97]

Thankyou for this amazing video

[@user-vt5nf6is9j]

Thank you very much! Your video so helpful for online teaching)

[@DavidAloro-kc2bp]

Excellent

[@AmyYTZhang]

just wondering: for each set of tubes, the salt solution is inside( Zn2+, Al3+, Pb 2+, Ca 2+,Fe3+, Fe2+, Cu2+, NH4+), while the addition solution are NaOH and NH3. is it correct?

[@MrJansenTan]

yes that's correct :)

[@dedinagames]

Really cool, thank u

[@njoneone7599]

thanks 😊

[@roger2bro]

What are the concentrations/molarities in each tube, and in the solutions that you are adding?

[@MrJansenTan]

hi, the sodium hydroxide and aqueous ammonia are 1 mol/dm³ while the salt solutions are 0.5 mol/dm³

[@meenuchauhan3337]

Really helped me a lot👍👍👍

[@kosy7580]

Thank you!!!!! Really helped a lot. 😋😋

[@olhakravtsova6023]

Nice video! II want use it for my students! But could you explain please why you are using NH3? Or it is NH4OH?

[@MrJansenTan]

thanks! Since NH₃ is a weak alkali, it dissociates partially in water. Therefore, aqueous ammonia mainly consists of NH₃ molecules. To write it as NH₄OH is less accurate as that would imply it is ionic and consists entirely of NH₄⁺ and OH⁻ ions.
Hence, we would write the equation for dissociation as such:
NH₃ + H₂O ⇌ NH₄⁺ + OH⁻

[@olhakravtsova6023]

@@MrJansenTan Thanks a lot