Explain why lead can be used for this purpose but mercury cannot?
2007-01-05 07:03:55 · 10 answers · asked by :) Anfield 2 in Science & Mathematics ➔ Chemistry
A solder joint needs to be solid at working temperatures in electrical devices. Mercury is liquid.
However, mercury is used to make electrical connections in certain switches where contact is temporary and reversible.
2007-01-05 07:06:34 · answer #1 · answered by Jerry P 6 · 0⤊ 0⤋
BTW - most solders these days no longer contain lead, as it is poisonous. Those that do, or did, were not pure lead, but a mixture of lead and other metals (eg. tin, perhaps silver and copper). A mixture of metals is generally referred to as an alloy.
It is possible to form alloys with Mercury. These are known as amalgams. If you have had a filling at the dentist you may have heard the term. In dentistry mercury is mixed cold with other metals, it is then put inside a tooth where it rapidly hardens. I expect a similar technique could be used for joining electrical conductors, however mercury is even more poisonous than lead (dentists take special precautions). In addition these amalgams may also lack some of the other good characteristics of lead solder like cheapness, electrical conductivity, reasonably high melting point etc.
2007-01-05 18:43:37 · answer #2 · answered by AT 1 · 0⤊ 0⤋
Solder is a solid mixture of tin and lead. The ratio of tin to lead is chosen to get a material with a relatively low melting point (lower than the melting point of lead) but not so low that it isn't a solid at room temperature.
Possible candidates for solder should have an appropriate melting point.
2007-01-05 16:12:01 · answer #3 · answered by primenumber 3 · 0⤊ 0⤋
The heat melts the lead which becomes solid again when it cools. Mercury is generally liquid and does not solidify. Silver is also used in solder.
2007-01-05 15:07:53 · answer #4 · answered by Anonymous · 0⤊ 0⤋
lead-free solder
A coil of lead-free solder wire
According to the European Union Waste Electrical and Electronic Equipment Directive (WEEE) and Restriction of Hazardous Substances Directive (RoHS), lead had to be eliminated from electronic systems by July 1, 2006, leading to much interest in lead-free solders. These contain tin, copper, silver, and sometimes bismuth, indium, zinc, antimony, and other metals in varying amounts. The lead-free replacements for conventional Sn60/Pb40 solder have higher melting points, requiring re-engineering of most components and materials used in electronic assemblies. Lead-free solder joints may produce mechanically weaker joints depending on service and manufacture conditions, which may lead to a decrease in reliability using such solders. "Tin Whiskers" are another problem with many lead-free solders, where slender crystals of tin slowly grow out of the solder joint. These whiskers can bridge a short circuit years after a device's manufacture.
2007-01-05 15:08:16 · answer #5 · answered by beckett 2 · 1⤊ 0⤋
mercury is liquid at room temperature so it wont work as a solder as it would but liquid and not join the wires together
2007-01-05 15:08:20 · answer #6 · answered by julie t 5 · 1⤊ 0⤋
Pure mercury is not a solid at normal room temperature. Lead has a low melting point, but is solid at normal temperature.
2007-01-05 15:07:14 · answer #7 · answered by Thomas K 6 · 0⤊ 0⤋
lead would be solid at room temperature after it is heated for joining the wires. mercury is liquid at room temperature and would not joing wires also mercury is posionous so its not used
2007-01-05 15:08:34 · answer #8 · answered by izzy 1 · 1⤊ 0⤋
You can melt lead, then when it cools it goes solid again. Lead is a very good conductor of electricity, so good for wire joints. Good luck.
2007-01-05 15:10:22 · answer #9 · answered by Anonymous · 0⤊ 1⤋
because mercury is liquid duh!!!!!!!
2007-01-05 15:07:25 · answer #10 · answered by I-love-taz 1 · 0⤊ 0⤋