Copper and its alloys

How copper interacts with other compounds

[Deposit Photos]

Cop­per is a non-fer­rous soft met­al which has been used by hu­man­i­ty for sev­er­al thou­sand years. Cop­per con­tin­ues to play an im­por­tant role and is wide­ly used in in­dus­try and for oth­er pur­pos­es.

Gen­er­al char­ac­ter­is­tics of the met­al

Cop­per is found in the fourth ma­jor pe­ri­od and 11-th group of the pe­ri­od­ic ta­ble. The atom­ic num­ber of cop­per is 29, its atom­ic weight is 63.546. Cop­per has two sta­ble nat­u­ral iso­topes, with the mass num­bers 63 and 65. The Latin name of the el­e­ment is cuprum, and the chem­i­cal sym­bol is Cu.

Copper melting [Wikimedia]

Cop­per has high duc­til­i­ty and is an ex­cel­lent con­duc­tor of heat and elec­tric­i­ty. Its melt­ing tem­per­a­ture is 1084.62 de­grees Cel­sius. The den­si­ty of the met­al is 8.96 g/cm3. In na­ture, the el­e­ment is en­coun­tered both in min­er­als and in free form.

Chem­i­cal prop­er­ties of cop­per

Cop­per is a rather chem­i­cal­ly in­ert met­al, with two ox­i­da­tion states shown in com­pounds: +1 and +2.

[Deposit Photos]

Sub­stances in which these val­ues change to +3 are en­coun­tered rarely. Cop­per in­ter­acts with oxy­gen, hy­drochlo­ric acid and oth­er com­pounds at high tem­per­a­tures. Also, on heat­ing a pro­tec­tive ox­ide film forms on the sur­face of the met­al, which pro­tects it from fur­ther ox­i­da­tion. Cop­per in­ter­acts with sim­ple sub­stances: se­le­ni­um, halo­gens and sul­fur. The el­e­ment can form com­plex com­pounds or bi­na­ry salts. Al­most all com­plex cop­per com­pounds are poi­sonous. Mono­va­lent cop­per in var­i­ous com­pounds read­i­ly ox­i­dizes to bi­va­lent cop­per.

Here you’ll find awe­some ex­per­i­ments for learn­ing prop­er­ties of cop­per.

Cop­per al­loys and their prop­er­ties

Nu­mer­ous al­loys con­tain a cop­per base. When cer­tain com­po­nents are added, the prop­er­ties of the cop­per al­loy are sig­nif­i­cant­ly im­proved in com­par­i­son with pure cop­per.

The fol­low­ing al­loys ex­ist:

Brass cups [Flickr, Creative commons by The Living Room is licensed under CC BY 2.0]

  • brass – a com­bi­na­tion of cop­per and zinc in var­i­ous ra­tios (this al­loy has high dura­bil­i­ty and re­sis­tance to chem­i­cal im­pact);

  • bronze – a cop­per al­loy with 12% tin;

  • cupron­ick­el – an al­loy of 5–30% nick­el and cop­per;

  • con­stan­tan – an al­loy of 45% nick­el and 55% cop­per.

Cop­per ox­ide

Copper(I) oxide [Wikimedia]

Cop­per(I) ox­ide is a brown-red sol­id sub­stance with a mo­lar mass of 143.09 g/mol. Its melt­ing tem­per­a­ture is 1,232 de­grees Cel­sius, and boil­ing tem­per­a­ture is 1,800 de­grees Cel­sius. Cop­per ox­ide does not dis­solve in wa­ter, but dis­solves in acids. Cop­per(I) ox­ide is di­lut­ed in a con­cen­trat­ed so­lu­tion of am­mo­nia, form­ing the col­or­less com­plex [Cu(NH₃)₂]⁺, and eas­i­ly ox­i­dizes in air to an am­mo­ni­um com­plex of a blue-vi­o­let col­or [Cu(NH₃)₄(H₂O)₂]²⁺, which dis­solves in hy­drochlo­ric acid with the for­ma­tion of Cu­Cl₂. Cop­per(I) ox­ide can be ob­tained by the ox­i­da­tion of cop­per in a lack of oxy­gen, the equa­tion of the re­ac­tion is:

4Cu + O₂ → 2 Cu₂O.

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