Specific Heat

DIRECTIONS: Use q = (m)(ΔT)(Cp) to solve the following problems. Show all work and units.

1. A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°C to 175°C. Calculate the specific heat capacity of iron.

2. How many joules of heat are needed to raise the temperature of 10.0 g of aluminum from 22°C to 55°C, if the specific heat of aluminum is 0.90 J/g°C?

3. To what temperature will a 50.0 g piece of glass raise if it absorbs 5275 joules of heat and its specific heat capacity is 0.50 J/g°C? The initial temperature of the glass is 20.0°C.

4. Calculate the heat capacity of a piece of wood if 1500.0 g of the wood absorbs 6.75×104 joules of heat, and its temperature changes from 32°C to 57°C.

5. 100.0 mL of 4.0°C water is heated until its temperature is 37°C. If the specific heat of water is 4.18 J/g°C, calculate the amount of heat energy needed to cause this rise in temperature.

6. 25.0 g of mercury is heated from 25°C to 155°C, and absorbs 455 joules of heat in the process. Calculate the specific heat capacity of mercury.

7. What is the specific heat capacity of silver metal if 55.00 g of the metal absorbs 47.3 calories of heat and the temperature rises 15.0°C?

8. If a sample of chloroform is initially at 25°C, what is its final temperature if 150.0 g of chloroform absorbs 1.0 kilojoules of heat, and the specific heat of chloroform is 0.96 J/g°C?

Specific and Conservation of Energy

1.  A 500 g piece of iron changes 7°C when heat is added. How much heat energy produced this change in temperature?

2.  When 1255 J of energy is lost from a 125 g object, the temperature decreases from 45.0°C to 40.0°C. What is the specific heat of this object?

3.  5021 J of heat energy is added to a liquid with a specific heat of 2.26 J/g°C. If the temperature increases from 20.°C to 33°C, what is the mass of the liquid?

4. If a piece of aluminum metal with a mass of 6550 grams has a temperature of 50.0 o C and it is dropped into a swimming pool full of water at 25.0 oC, how much heat energy was transferred to the pool water? Cp for Al is 0.8897 J/gCo

5. How much energy is required to heat a #10 iron nail with a mass of 7.0 grams from 250 oC until it becomes red hot at 7500 oC.

6.  If 5750 joules of energy are added to 455 grams of granite at 24.00 C, what is the final temperature of the granite? Cp granite is 0.79 J/g oC.

7.  If a piece of aluminum with a mass of 3.99 g and a temperature of 100.0 oC is dropped in 10.0 g of water at 21.0 oC, what will be the final temperature of the system?

8.  A piece of unknown metal with a mass of 7.79 g is heated to 100.00 oC and dropped into 10.0 g of water at 22.00 oC. The final temperature of the system is 23.83 oC. What is the specific heat capacity of the metal? Use page one of the reference table to identify the metal.

1. How much heat is required to melt 233.0 grams of ice into water, from -15.00°C to room temperature (25.00°C)? ANSWER: heating ice = 7095 J, heating water = 24349 J, heat of fusion = 77822 J, TOTAL HEAT = 110 kJ

2. How much heat is required to change 32.5 grams water into steam, from room temperature (25.0°C) to 115°C? ANSWER: heating water = 10189 J, heating steam = 960 J, heat vaporization = 73418 J, TOTAL HEAT = 85 kJ

3. How much heat is needed to melt 1.43 grams of ice into water from -5.34°C to 84.3°C?

ANSWER: heating ice = 15.5 J, heating water = 504 J, heat fusion = 478 J, TOTAL HEAT = 998 J

4. How much heat is needed to convert 0.232 grams water into steam, from 32.5°C to 112°C?

ANSWER: heating water = 65.5 J, heating steam = 5.48 J, heat vaporization = 524 J, TOTAL HEAT = 595 J

5. How much heat do you need to add to 3.22 grams H2O to raise the temperature from -23.0°C to 152°C?

ANSWER: heating ice=150 J, heating water=1346 J, heating steam=330 J, heat fusion=1075 J, heat vaporization=7274 J, TOTAL=10. kJ

6. How much heat is needed to raise the temperature of 199 grams H2O from -10.3°C to 154°C?

ANSWER: heating ice=4161 J, heating water=83182 J, heating steam=21170 J, heat fusion=66466 J, heat vaporization=449541 J, TOTAL = 625 kJ

Write the equilibrium expressions for each reaction.

1. 2NO2 (g) àN2O4 (g)

2. H2 (g) + I2 (g) à2HI (g)

3. CaSO4 (s) àCa2+ (aq) + SO42– (aq)

4. Mg(s) + 2Ag+ (aq) à Mg2+ (aq) + 2Ag (s)

5. C (s) + H2O (g) àCO (g) + H2 (g)

6. CO2 (aq) + H2O (l) à H+ (aq) + HCO3– (aq)

7. CO (g) + 2H2 (g) à CH3OH (g)

8. 2POCl3 (g) à2PCl3 (g) + O2 (g)

9. Sn (s) + 2CO2 (g) àSnO2 (g) + 2CO (g)

10. 2HBr (g) àH2 (g) + Br2 (l)

11. O2 (g) + NO2 (g) àO3 (g) + NO (g)

12. Fe (s) + H2O (g) àFeO (s) + H2 (g)

Balance the following equations. Write the equilibrium expressions for each reaction.

13. __O3 (g) à__O2 (g)

14. __NO (g) + __Cl2 (g) à __NOCl (g)

15. __CO (g) à__C (s) + __O2 (g)

16. __SO3 (g) à __SO2 (g) + __O2 (g)

17. __HCl (g) + __O2 (g) à __H2O (l) + __Cl2 (g)

18. __Sb2S3 (s) + __H2 (g) à__Sb (s) + __H2S (g)