..ooo Verizon LTE 4:18 PM 76% nersp.nerdc.ufl.edu CO5 Write thr chemical reactio
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..ooo Verizon LTE 4:18 PM 76% nersp.nerdc.ufl.edu CO5 Write thr chemical reaction of the analgamation process for low and high copper amalgams and discass how the difermer reaction provlacts afect the final properties of the amalgam. Contrastloor and itigh capper amalgams. The Setting Reaction The above pictures (a d) show that dental amalgam alloy particles are mixed with mercury.During the mixing process silver, tin and copper atoms are dissolved in the mercury where they start forming different precipitates. These precipitates form a matrix that retain the remaining partly dissolved amalgam alloy particles. The amount of mercury needed to wet all particles and occupy the space between the particles range from 40-60% mercury by weight. In other words, the final "silver filling" after it has been condensed contains around 40-50% mercury. Traditional Amalgams (low copper amalgams) Ag 3Sn Hg Ag2Hg3. Sn7.8Hg Ag3Sn (unreacted) The Ag3Sn phase is the gamma phase in the silver-tin phase diagram, the Ag2Hg3 phase is the gamma phase in the silver-in phase diagram, and the Sn7.8Hg phase is the gamma phase in the tin- mercury phase diagram. To avoid confusion. the Ag3Sn is therefore called the gamma phase, the Ag2Hg3 the gamma-1 phase and the Sn7-8 the gamma 2 phase. Below is a picture showing how the set low-copper amalgam looks Admixed High Copper AmalgamExplanation / Answer
Amalgams are alloys (mixtures) of metals where the participating metals are in 0 oxidation state.
Ag3Sn + Hg -----> Ag2Hg3 Sn7-8Hg + Ag3Sn (unreacted)
Start with Sn8Hg and balance Sn atoms on both sides.
9 Ag3Sn + 37 Hg ----> 12 Ag2Hg3 + Sn8Hg + Ag3Sn (unreacted)
Since the atoms present in an alloy are in 0 oxidation state, the reaction cannot be termed as oxidation or reduction. Infact, the reaction is a displacement reaction where the metal atoms change their respective positions.
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