The African bombardier beetle Stenaptinus insignis can emit a jet of defensive s
ID: 1553126 • Letter: T
Question
The African bombardier beetle Stenaptinus insignis can emit a jet of defensive spray from the moveable tip of its abdomen (Figure 1). The beetle's body has reservoirs of two different chemicals; when the beetle is disturbed, these chemicals are combined in a reaction chamber, producing a compound that is warmed from 20 degree C to 100 degree C by the heat of reaction. The high pressure produced allows the compound to be sprayed out at speeds up to 19 m/s (68 km/h), scaring away tethered to a wire fastened to its back by wax. It is responding to having its left foreleg pinched by forceps. The beetle is 2 cm long.) Calculate the heat of reaction of the two chemicals. Assume that the specific heat capacity of the two chemicals and the spray is the same as that of water, 4.19 times 10^3 J/kg middot K, and that the initial temperature of the chemicals is 20 degree C. Express your answer using two significant figures.Explanation / Answer
Q = C(t2-t1)
Where Q is heat/kg
C is specific heat capacity
= 4.19*10^3*80 = 335.2*10^3 J/kg
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