The most spectacular household chemicals

The most use­ful sub­stance in house­hold chem­i­cals, for home chemists, is sur­face ac­tive agents, or SAAs. They sig­nif­i­cant­ly re­duce the elec­tro­stat­ic ten­sion be­tween par­ti­cles of sub­stances, break­ing up con­glom­er­ates into small­er sizes. This fea­ture is used in re­mov­ing dirt on cloth­ing etc. And on our list of the chem­i­cal re­ac­tions which you can make with house­hold chem­i­cals, SAAs cre­ate im­pres­sive ef­fects in ex­per­i­ments.

First ex­per­i­ment: a foam­ing vol­cano in a jar

It’s very easy to con­duct this in­ter­est­ing ex­per­i­ment at home.

You will need:

• hy­droperite (hy­dro­gen per­ox­ide). The high­er the con­cen­trate of so­lu­tion, the more in­ten­sive the re­ac­tion will be, and the more ef­fec­tive the erup­tion of the “vol­cano”. So buy pills at the phar­ma­cy and dis­solve them in a small amount of wa­ter just be­fore use, in the pro­por­tion of 1/1 (the so­lu­tion will be 50%, an ex­cel­lent con­cen­tra­tion);
• a small amount of dish­wash­ing liq­uid di­lut­ed with wa­ter. 50 mil­lime­ters will be enough. You can add col­or­ing if you wish. Now you need to do a bit of chem­istry to get an ef­fec­tive cat­a­lyst — cop­per am­mine. Work with it care­ful­ly, adding a few drops of am­mo­nia to cop­per sul­fate un­til it dis­solves com­plete­ly

Let’s look at the for­mu­la:

Cu­SO₄ + 6NH₃ + 2H₂O = [Cu(NH₃)₄](OH)₂(cop­per am­mine) + (NH₄)₂SO₄

Re­ac­tion of the break­down of per­ox­ide:

2H₂O₂ → 2H₂O + O₂

Mak­ing the vol­cano: mix am­mine with the wash­ing so­lu­tion in a jar or a long-necked flask and quick­ly add the hy­droperite so­lu­tion. The “erup­tion” may go up very high into the air, so we rec­om­mend you place a con­tain­er un­der the ex­per­i­ment.

Sec­ond ex­per­i­ment: re­ac­tion be­tween acid and sodi­um salt

The most fa­mil­iar com­pound that is present in ev­ery home, sodi­um salt, is kitchen soda. It re­acts with acid (to save time, you can use acetic acid or cit­ric acid). As a re­sult a new salt, a lit­tle wa­ter and car­bon diox­ide are formed. You can de­tect that it is be­ing re­leased by the hiss­ing and bub­bles in the area of the re­ac­tion.

Third ex­per­i­ment: “swim­ming” soap bub­bles

You can use a sim­ple com­pound: kitchen soda, which is used for clean­ing kitchen uten­sils, re­mov­ing fat, and for culi­nary pur­pos­es. You will need:

• an aquar­i­um with a wide bot­tom;
• kitchen soda (150—200 grams);
• acetic acid in a so­lu­tion of 6—9%;
• soap bub­bles (mak­ing bub­bles your­self is not hard, mix wa­ter, dish­wash­ing liq­uid and glyc­erin).

Sprin­kle salt even­ly on the bot­tom of the aquar­i­um, and pour acetic acid over it. The car­bon diox­ide that is re­leased is heav­ier than the air, so it will stay at the bot­tom of the aquar­i­um. How do we tell that it’s there? Place a light­ed match on the bot­tom, and the car­bon diox­ide will put it out im­me­di­ate­ly.

NaH­CO₃ + CH₃­COOH → CH₃­COONa + H₂O + CO₂↑

Blow bub­bles into the aquar­i­um. They will slow­ly move in a hor­i­zon­tal line (the in­vis­i­ble bound­ary where the car­bon diox­ide and air touch, as if they were swim­ming in the aquar­i­um).

Fourth ex­per­i­ment: an­oth­er vari­a­tion on the theme of soda and acid.

You will need:

• var­i­ous types of non-hy­gro­scop­ic food prod­ucts (for ex­am­ple gum­drops). Cut them with a sharp knife into strips (1-3 cm);
• a glass with di­lut­ed soda (one ta­ble­spoon);
• a glass with a so­lu­tion of ac­etate or an­oth­er avail­able acid (ap­ple, cit­ric).

Place the gum­drop pieces in the glass with the soda so­lu­tion. Leave them there for 10 min­utes, then move them to the oth­er glass with the acidic so­lu­tion.

The gum­drop pieces, like live worms, will form bub­bles of car­bon diox­ide gas and float to the sur­face, where the bub­bles will evap­o­rate, the lift­ing pow­er of the gas will dis­ap­pear and the pieces will sink. Bub­bles will form again, and the process will con­tin­ue un­til the reagents in the con­tain­er have run out.

Fifth ex­per­i­ment: demon­stra­tion of the prop­er­ties of an al­ka­li on lit­mus pa­per

Most wash­ing agents con­tain caus­tic soda, the most com­mon al­ka­li. You can prove they are present in the so­lu­tion of a wash­ing agent with a sim­ple ex­per­i­ment which a young en­thu­si­ast can eas­i­ly pre­pare at home.

1. Take a piece of lit­mus pa­per
2. Dis­solve a lit­tle liq­uid soap in wa­ter
3. Low­er the lit­mus pa­per into the soap.
4. Wait un­til the pa­per turns blue, which will show the al­ka­line re­ac­tion of the so­lu­tion. Click here for find­ing more bright re­ac­tions be­tween “ev­ery­day com­pounds”.

Sixth ex­per­i­ment: col­or bursts and pat­terns in milk

This ex­per­i­ment is based on the prop­er­ties of in­ter­ac­tion of fats and SAA. Fat mol­e­cules have a dual struc­ture is dual: they have a hy­drophilic end (that in­ter­acts and dis­so­ci­ates with wa­ter) and a hy­dropho­bic end (the “tail” of a poly­atom­ic com­pound that is in­sol­u­ble in wa­ter).

1. Pour milk into a wide, shal­low con­tain­er (as the “can­vas” on which the col­or burst will be vis­i­ble). Milk is a sus­pen­sion of fat mol­e­cules in wa­ter.
2. With a pipette, add sev­er­al drops of a wa­ter-sol­u­ble liq­uid dye into the con­tain­er of milk. You can make a mul­ti-col­ored ex­plo­sion, by adding dif­fer­ent dyes to dif­fer­ent parts of the con­tain­er.
3. Then soak a cot­ton swab in the dish­wash­ing liq­uid and touch the sur­face of the milk. The white “can­vas” of milk turns into a mov­ing pal­ette of col­ors which form spi­rals in the liq­uid, and twist into in­cred­i­ble shapes.

The ba­sis of this phe­nom­e­non is the abil­i­ty of SAAs to break down a film of fat mol­e­cules on the sur­face of a liq­uid into frag­ments. Fat mol­e­cules, push­ing off with their hy­dropho­bic “tails”, shift around with­in the milk sus­pen­sion, and the par­tial­ly undis­solved dye moves with them.