Question

35. Consider the following specific heats of metals. Metal Specific Heat Copper 0.385 J/(g. °C) Cobalt0.418 J/(g °C) Chromium 0.447 J/(g. °C) Gold Silver0.237 J/(g. °C) 0.129 J/(g.°C) If the same amount of heat is added to 100-g samples of each of the metals, which are all at the same temperature, which metal will reach the lowest temperature? a. copper b. cobalt c chromium d. gold e. silver x 36. The sign of AH for the process 12(s)- 12(3) is positive, and the process is endothermic negative, and the process is endothermic c. positive, and the process is exothermic d. negative, and the process is exothermic e. impossible to predict with confidence because AH for 12(s) and AHo for 12(g) are not given.

Answer 1

Q35. Correct answer is (c.) Chromium

Q36. Correct answer is (a.) positive, and the process is endothermic

Explanation

Q35. Specific heat is the amount of heat required to raise the temperature of 1 gram of substance by 1 ^oC. If specific heat is higher then more heat is required to raise the temperature of substance. If amount of heat is fixed, then highest specific heat will yield lowest temperature. Form the given data, chromium has the highest specific heat. Hence chromium will have lowest temperature.

Q36. According to the given chemical equation, iodine in solid form is converted to iodine in gaseous form. Converting a substance from solid to gaseous form requires adding heat to the substance to first melt the solid and then boil the liquid. Since heat is added to the system therefore the process is endothermic and value of enthalpy change will be positive