Joules of Heat

HEAT / Joules Practice Problems Bill Name: KEY How many joules of heat are absorbed to raise the temperature of 435 grams of water at 1 atm from 25°C to its boiling point, 100°C?   4.5 x 10^4 J 4 x 10^5 J 2.5 x 10^7 J 7.4 x 10^7 J Which temperature represents the highest average kinetic energy of the particles in a sample of matter? Highest Temp! 298 K 267 K 273 K 285 K What is the total amount of heat required to completely melt 347 grams of ice at its melting point? 334 J 1450 J 115898 J 784,000 J 4.1 Starting as a solid, a sample is heated at a constant rate. The graph below shows the changes in temperature of this sample. Temperature Versus Time for a Sample   temperature vs. time graph What is the melting point of the sample and the total time required to completely melt the sample after it has reached its melting point?   50°C and 3 min 110°C and 4 min 50°C and 5 min 110°C and 14 min 5.2 The graph represents the uniform heating of a solid, starting below its melting point. temperature vs. time graph Which portion of the graph shows the solid and liquid phase existing in equilibrium? AB BC CD DE 6.1 What is the number of Kelvin degrees between the freezing point and the boiling point of water? 100 212 273 373 7.2 What is the amount of heat released when a 5.00-gram sample of water changes from liquid to solid at 0°C? 334 J 1670 J 2260 J 11300 J 8.4 In a laboratory where the air is 22°C, a steel cylinder at 100°C is submerged in a sample of water at 40°C. In this situation, heat flows from both the air and the water to the cylinder both the cylinder and the air to the water the air to the water and from the water to the cylinder the cylinder to the water and from the water to the air   9.4 Which transfer of energy occurs when ice cubes are placed in water that has a temperature of 45°C? Chemical energy is transferred from the ice to the water. Chemical energy is transferred from the water to the ice. Thermal energy is transferred from the ice to the water. Thermal energy is transferred from the water to the ice.   10. The graph below represents the uniform heating of a substance, starting below its melting point, when the substance is solid.   temperature vs. time graph Which line segments represent an increase in kinetic energy? AB and BC AB and CD BC and DE DE and BF 11. Which physical change is endothermic? CO2(s) -> CO2(g) CO2(l) -> CO2(s) CO2(g) -> CO2(l) CO2(g) -> CO2(s) 12. The temperature of a sample of matter is a measure of the: total kinetic energy of the particles in the sample total potential energy of the particles in the sample average potential energy of the particles in the sample average kinetic energy of the particles in the sample   13. Which type of energy is associated with the random motion of atoms and molecules in a sample of air? chemical energy electrical energy nuclear energy thermal energy   14. What occurs when a 35-gram aluminum cube at 100°C is placed in 90 grams of water at 25°C in an insulated cup? Heat is transferred from the aluminum to the water, and the temperature of the water decreases.   Heat is transferred from the aluminum to the water, and the temperature of the water increases. Heat is transferred from the water to the aluminum, and the temperature of the water decreases. Heat is transferred from the water to the aluminum, and the temperature of the water increases.   15. The graph represents the relationship between temperature and time as heat was added uniformly to a substance starting at a solid below its melting point.   temperature vs. time graph During the BC portion of the curve, the average kinetic energy of the molecules of the substance: increases and the potential energy increases decreases and the potential energy increases remains the same and the potential energy increases remains the same and the potential energy decreases   Calculations: 16. 650.0 joules of heat are added to 25.0 grams of water at 35°C. What is the final temperature of the water? q = mcΔT 650.0 J = 25.0 g x 4.18 J/g°C x ΔT ΔT = 6.22°C Final Temp = 35°C + 6.22°C = 41.22°C 17. 3500.0 joules of heat are needed to vaporize 55.0 grams of water at its boiling temperature. What is the Heat of Vaporization of this liquid? q = mHv 3500.0 J = 55.0 g x Hv Hv = 63.6 J/g Handwritten text: The majority of the text appears to be handwritten in a cursive style. Graphs: Two temperature vs. time graphs are present, each labeled with letters along the x-axis (A, B, C, D, E, F) and numbers along the y-axis. Equations: Several mathematical equations are present, including: q = mcΔT q = mHv Arrows: Arrows are used to indicate the direction of heat transfer in some of the questions.