Question

19. How much heat is liberated (in kJ) from 2.47E+2 g of silver when it cools from 8.86E+1 °C to 2.57E+1 °C? The heat capacity of silver is 0.235 J g^{-1} °C^{-1} g−1°C−1. Note, "heat liberated" implies that the change in heat is negative. Enter a positive number

20. A sample of sand initially at 2.18E+1 °C absorbs 1.386E+3 J of heat. The final temperature of the sand is 6.7E+1 °C. What is the mass (in g) of sand in the sample? The heat capacity of sand is 0.84 J g^{-1} °C^{-1}g−1°C−1.

21. 1.13E+1 ounces of water are heated during the preparation of a cup of coffee. 1.186E+3 J of heat are added to the water, which is initially at 1.96E+1 °C. What is the final temperature of the coffee?

38. A sample of copper absorbs 4.28E+1 kJ of heat, resulting in a temperature rise of 6.86E+1 °C. Determine the mass (in kg) of the copper sample if the specific heat capacity of copper is 0.385 J/g°C.

39. A 5.51E+1 g sample of water at 9.979E+1 °C is placed in a constant pressure calorimeter. Then, 2.31E+1 g of zinc metal at 2.19E+1 °C is added to the water and the temperature drops to 9.61E+1 °C. What is the specific heat capacity of the zinc metal measured in this experiment?

40. A 2.61E+1 g sample of aluminum at 1.009E+2 °C is added to 1.001E+2 g of water at 2.23E+1 °C in a constant pressure calorimeter. What is the final temperature of the water in °C? The specific heat capacity of aluminum is 0.903 J/g°C .

43. Copper (Cu) pellets with a mass of 2.71E+1 g at 9.970E+1 °C are placed in a constant pressure calorimeter of negligible heat capacity containing 1.07E+2 mL of water. The temperature of the water rises from 2.19E+1 °C to 2.31E+1 °C. What is the specific heat capacity of the copper pellets?

In scientific notation.

44. When 1.03E-1 g of Zn(s) combines with 5.86E+1 mL of HCl(aq) in a coffee cup calorimeter, all of the zinc reacts, which increases the temperature of the HCl solution from 2.31E+1 °C to 2.49E+1 °C: Zn(s) + 2HCl(aq) → ZnCl_22 (aq) + H_22 (g)

Calculate the enthalpy change of the reaction ΔH_{rxn}rxn in J/mol. (Assume the volume of the solution doesn't change, density of the solution is 1.00 g/mL and the specific heat capacity of the solution is 4.184 J/g°C.) Answer in scientific notation.

48. What is the enthalpy of formation (\DeltaΔH^{\circ}∘_ff ) of NaHCO_33 (s) from its constituent elements.

49. Use standard enthalpies of formation to calculate the standard enthalpy of reaction for the following reaction:

2 H_22 S(g) + 3 O_22 (g) → 2 H_22 O(l) + 2 SO_22 (g) \DeltaΔH^{\circ}∘_{rxn}rxn​

ALL ANSWERS MUST BE IN SCIENTIFIC NOTATION.

Answer 1