science lab experiments

The Pop Test

The pop test is used to conclude whether there is hydrogen (H2) present.

The pop sound is the sound of the hydrogen combusting with oxygen.

2Mg + 2HCl -> 2MgCl + H2

We mix together Magnesium and Hydrochloric acid to react, which forms Magnesium Chloride and Hydrogen gas.

Equipment:

2 test tubes

Magnesium

Hydrochloric acid  

Splint

Bunsen burner

Method:

1. Put Mg in test tube
2. HCl in test tube
3. Put another test tube over top to capture H2 gas
4. Light it on fire.

Observation: when we added the acid to the Mg, it started to bubble and it was giving off gas.

Once we trapped the gas we lit it on fire resulting in a high pitched pop. This indicated that the gas was hydrogen.

Tollens’ Test

Tollens reagent is used to distinguish if something is a sugar

Tollens will only react with a sugar and will create a silver mirror

C2H4O + 2Ag+ + 2OH- -> C2H4O2 + 2Ag + H2O

Equipment:

Test tube

Tollens

Sugar

Method:

1.  Add sugar to test tube

2. Add tollens to the test tube

3. Swirl it around

Observation When we added the reagent we expected to see silver mirror form on the inside of the test tube. Instead of it going silver shiny it was more a dull silver and wasn't very shiny.

Nickel Amine Complex

Adding ethylenediamine to nickel replaces two waters with one ethylenediamine.

We can do this three times to form tris ethylenediamine nickel II

We can do this using just NH2 instead to form [Ni(NH2)6]

[Ni(H2O)6] + NH2CH2CH2NH2 -> [Ni(H2O)4(en)] + 2H2O

[Ni(H2O)4(en)] + en -> [Ni(H2O)2(en)2] + 2H2O

[Ni(H2O)2(en)2] + en -> [Ni(en)3] + 2H2O

Equipment:

3 Test tubes

We need a b

eaker

We need the ethylenediamine

We also need the nickel.

Observation:  we started with a nickel water complex we started adding ethylenediamine to the complex as we added more en the colour started to change from teal to blue then to pink. This is because as we add more en, it replaces the water molecules on the complex. The picture below is the hexammine complex we also made with some of the other complex on top.