Q1)

Suppose that 23 g of each of the following substances is initially at 27.0 C. What is the final temperature of each substance upon absorbing 2.45 kJ of heat?

Part A

gold

Part B

silver

Part C

aluminum

Part D

water

Q2) A 32.5 g iron rod, initially at 22.7 C, is submerged into an unknown mass of water at 63.1 C, in an insulated container. The final temperature of the mixture upon reaching thermal equilibrium is58.4 C.

What is the mass of the water?

Express your answer to two significant figures and include the appropriate units.

Q3)Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction: NH4NO3(s)NH+4(aq)+NO3(aq) In order to measure the enthalpy change for this reaction, 1.25 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8 C and the final temperature (after the solid dissolves) is 21.9 C.

Part A

Calculate the change in enthalpy for the reaction in kilojoules per mole. (Use 1.0g/mL as the density of the solution and 4.18J/gC as the specific heat capacity.)

Express your answer to two significant figures and include the appropriate units.

Q4)Zinc metal reacts with hydrochloric acid according to the following balanced equation.

Zn(s)+2HCl(aq)ZnCl2(aq)+H2(g)

When 0.107 g of Zn(s) is combined with enough HCl to make 54.4 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.3 C to 24.3 C.

Part A

Find Hrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/gC as the specific heat capacity.)