“Silver mirror” experiment

How to make a mirror from 2 solutions

How can you make a mir­ror from two so­lu­tions in 20 min­utes? Here’s an ex­per­i­ment to make a mir­ror sur­face based on the qual­i­ta­tive “Sil­ver mir­ror re­ac­tion”.

Safe­ty pre­cau­tions

Wear gloves and pro­tec­tive glass­es and work in a well-ven­ti­lat­ed room when con­duct­ing the ex­per­i­ment.

Reagents and equip­ment:

  • sil­ver ni­trate 5 g/l;
  • glu­cose 5 g/l;
  • am­mo­nia so­lu­tion 10%;
  • sodi­um hy­drox­ide 5 g/l;
  • dis­tilled wa­ter 200 ml;
  • Petri dish;
  • beakers.

Step-by-step in­struc­tions

To pre­pare the sil­very so­lu­tion, name­ly the am­mo­nia so­lu­tion of sil­ver ox­ide (Tol­lens’ reagent), mix the so­lu­tion of sil­ver ni­trate and a few milliliters of sodi­um hy­drox­ide. A brown sed­i­ment of sil­ver ox­ide forms. Then add the am­mo­nia un­til the sed­i­ment dis­solves com­plete­ly. It’s im­por­tant to re­mem­ber that an abun­dance of am­mo­nia can af­fect the qual­i­ty off the cov­er­ing and the speed at which the sil­ver set­tles.

Into a Petri dish, pour the am­mo­nia so­lu­tion of sil­ver ox­ide (or Tol­lens’ reagent) and the glu­cose so­lu­tion. Af­ter a while the dish will start to be­come cov­ered with a thin lay­er of sil­ver. Rinse the residue of the re­ac­tive mix­ture from the Petri dish with wa­ter.

Pro­cess­es de­scrip­tion

Metal­lic coat­ings are wide­ly used in in­dus­try, in par­tic­u­lar coat­ings of sil­ver. The tech­nol­o­gy is based on the well-known “sil­ver mir­ror” re­ac­tion, i.e. the re­duc­tion of sil­ver ions from the am­mo­nia so­lu­tion of sil­ver ox­ide by any sub­stance from the alde­hyde group, for ex­am­ple glu­cose. The re­duced sil­ver set­tles on the sur­face of the Petri dish in the form of a mir­ror coat­ing.

НОСН₂(СНОН)₄HС=O (glu­cose) + 2[Ag(NH₃)₂]OH => НОСН₂(CHОН)₄СООH + 2Ag +4NH₃ + 2H₂O