Fig. 1 shows a technician measuring temperature while 50.0 g samples of tin and solder cool in identical crucibles. Solder is an alloy used to join copper p...
Question 1 Report
Fig. 1 shows a technician measuring temperature while 50.0 g samples of tin and solder cool in identical crucibles. Solder is an alloy used to join copper pipes in plumbing. Table 1 gives the cooling data.
| material | temperature where solidification starts / degrees C | temperature where solidification ends / degrees C |
|---|---|---|
| pure tin | 232 | 232 |
| solder | 190 | 183 |
(a) Use Table 1 to state the melting point of pure tin. [1]
(b) Describe the melting behaviour of the solder. [2]
(c) Explain why an alloy melts over a range of temperatures. [3]
(d) Use the data to explain one advantage of solder for joining copper pipes. [2]
(e) What apparatus is used to measure the temperature accurately? [1]
(f) Complete the safety advice: use tongs because the crucible is ____. [2]
Answer Details
(a) Pure tin melts at 232 °C. A pure substance solidifies, and therefore melts, at one fixed temperature. [1]
(b) Solder starts to solidify at 190 °C and finishes solidifying at 183 °C. Thus, it freezes over a 7 °C temperature range rather than at a single temperature. [2]
(c) An alloy contains more than one type of atom. The atoms have different attractions, or bonding environments, in different parts of the structure. Consequently, different parts need different amounts of energy and temperatures to melt, giving a melting range. [3]
(d) Solder melts at a lower temperature than pure tin. Less heating is required, so the copper pipe is less likely to be damaged during joining. [2]
(e) A thermometer or temperature probe is used to measure temperature accurately. [1]
(f) Use tongs because the crucible is hot and may cause burns. [2]
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