A spoon weighing 50 g was lowered to boiling water of 100 degrees, weighing 200 g, while the temperature dropped to 99 degrees. What material is the spoon made of if its initial temperature is 29 degrees?
mw = 200 g = 0.2 kg.
tv = 100 ° C.
Sv = 4200 J / kg * ° C.
ml = 50 g = 0.05 kg.
tl = 29 ° C.
t = 99 ° C.
In order to establish what material the spoon is made of, it is necessary to determine the specific heat capacity Сl, and then, according to the table of specific heat capacity of substances, determine which material it is.
Let’s write down the heat balance equation: mw * Cw * (tv – t) = ml * Cl * (t – tl).
Cl = mw * Cw * (tv – t) / ml * (t – tl).
Сl = 0.2 kg * 4200 J / kg * ° C * (100 ° C – 99 ° C) / 0.05 kg * (99 ° C – 29 ° C) = 240 J / kg * ° C.
According to the table of specific heat capacity of substances, this value corresponds to the metal silver.
Answer: a spoon made of silver Cl = 240 J / kg * ° C.
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