Science e-Portfolio Post 2

Hi everyone, this is my 2nd e-Portfolio post. Please enjoy!

Reflection on science experiences, laboratory sessions

Topics	Reflection
2P01- Properties of Acids and Bases	This was our 1st science lab lesson. I learnt about alkaline and acids. I got to taste acid and feel alkali for the 1st time in my life. I learnt that acid’s taste is sour while alkali feels soapy. I also learnt that different reagents have different effects on different pH indicators. In addition, I learnt that an acid can neutralize an alkali and vice versa.
2P02 -Strength of Acids and Alkalis	In this laboratory session, I learnt that acids and alkalis are conductors of electricity, unlike water, which is a non-conductor of electricity. The stronger the acids and alkalis, the better they conduct electricity. Strong acids are substances that ionise completely in water to produce hydrogen ions (H+), while strong alkalis are substances that ionise completely in water to produce hydroxide ions (OH-). However, weak acids and alkalis can only conduct electricity to a certain extent.
2P03	For this lab session, I learnt that the higher the volume of dilute sodium hydroxide, the higher the pH level. I also learnt that when alkali is added to acid, pH increases whereas when acid is added to alkali, pH decreases.
2P04 - When Dilute Acid Meets Metals	Today, I learnt that dilute acids react with reactive metals to produce hydrogen gas. To test for hydrogen, we can use a lighted splint into a test tube containing the gas. If the gas is hydrogen, the lighted splint will be extinguished and a ‘pop’ sound will be heard. I have also learnt that copper is a noble metal, therefore it is not affected by non-oxidizing acids. Copper's oxidation potential is lower than that of hydrogen, so it cannot displace hydrogen from hydrochloric acid. The measure of a material to oxidize or lose electrons is known as its 'oxidation potential.'
2P05 - When Dilute Acid Meets Carbonates	This experiment concludes that Dilute acid reacts with a carbonate to produce carbon dioxide gas. However the exception is when calcium carbonate reacts with sulphuric acid. This is because the reaction between calcium carbonate and sulfuric acid is incomplete. The product, calcium sulfate, is insoluble in water. It will form a coating around the insoluble calcium carbonate, hence preventing further reaction from taking place. Generally, all sulphates are soluble EXCEPT those of silver, lead, mercury(I), barium, strontium and calcium. Comparing with 2P04, hydrogen is a neutral gas, however carbon dioxide is acidic.
2P06 - When Acid Meets Alkali	This experiment demonstrates that an acid reacts with an alkali to produce a salt. Salt is neutral pH.
2P07 - When Alkali Meets Ammonium Salts	Alkali reacts with ammonium salt to produce ammonia gas. The ammonia gas is alkaline in nature. An alkali only shows its alkaline properties in the presence of water, thus dry red litmus paper does not change color when it reacts with ammonia gas.

Thank you!