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The coldest temperature ever recorded on Earth was
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- A rebreathing gas mask contains potassium superoxide, KO2, which reacts with moisture in the breath to give oxygen. 4KO2(s)+2H2O(l)4KOH(s)+3O2(g) Estimate the grams of potassium superoxide required to supply a persons oxygen needs for one hour. Assume a person requires 1.00 102 kcal of energy for this time period. Further assume that this energy can be equated to the heat of combustion of a quantity of glucose, C6H12O6, to CO2(g) and H2O(l). From the amount of glucose required to give 1.00 102 kcal of heat, calculate the amount of oxygen consumed and hence the amount of KO2 required. The ff0 for glucose(s) is 1273 kJ/mol.arrow_forwardfriend of yours reads that the process of water freezing is exothermic. This friend tells you that this can’t be true because exothermic implies “hot,” and ice is cold. Is the process of water freezing exothermic? If so, explain this process so your friend can understand it. If not, explain why not.arrow_forwardIf 14.5 kJ of heat were added to 485 g of liquid water, how much would its temperature increase?arrow_forward
- How much heat, in joules and in calories, must be added to a 75.0g iron block with a specific heat of 0.449 Jig C to increase its temperature from 25 C to its melting temperature of 1535 C?arrow_forwardExplain why oceanfront areas generally have smaller temperature fluctuations than inland areas.arrow_forwardDetermine whether the statements given below are true or false. Consider an endothermic process taking place in a beaker at room temperature. (a) Heat flows from the surroundings to the system. (b) The beaker is cold to the touch. (c) The pressure of the system decreases. (d) The value of q for the system is positive.arrow_forward
- A piece of lead of mass 121.6 g was heated by an electrical coil. From the resistance of the coil, the current, and the Time the current flowed, it was calculated that 235 J of heat was added to the lead. The temperature of the lead rose from 20.4C to 35.5C. What is the specific heat of the lead?arrow_forwardA book is held 6 feet above the floor and then dropped. Which statement is true? a.The potential energy of the book is converted to kinetic energy. b.The potential energy of the book is destroyed. c.Kinetic energy is created. d.The total energy of the system will not be conserved.arrow_forwardA piece of iron was heated to 95.4C and dropped into a constant-pressure calorimeter containing 284 g of water at 32.2C. The final temperature of the water and iron was 51.9C. Assuming that the calorimeter itself absorbs a negligible amount of heat, what was the mass (in grams) of the piece of iron? The specific heat of iron is 0.449 J/(gC), and the specific heat of water is 4.18 J/(gC).arrow_forward
- The specific heat of copper metal was determined by putting a piece of the metal weighing 35.4 g in hot water. The quantity of heat absorbed by the metal was calculated to be 47.0 J from the temperature drop of the water. What was the specific heat of the metal if the temperature of the metal rose 3.45C?arrow_forwardSuppose that you are closing a cabin in the north woods for the winter and you do not want the water in the toilet tank to freeze. You know that the temperature might get as low as 30. C, and you want to protect about 4.0 L water in the toilet tank from freezing. Calculate the volume of ethylene glycol (density = 1.113 g/mL; molar mass = 62.1 g/mol) you should add to the 4.0 L water.arrow_forwardA newspaper article about the danger of global warming from the accumulation of greenhouse gases such as carbon dioxide states that "reducing driving your car by 20.0 miles a week would prevent release of over 1000. pounds of CO₂ per year into the atmosphere." To decide if this is a reasonable statement, calculate the reduction in the number of pounds of CO₂ a car would release in a year if its use was decreased by 20.0 miles per week. Think about the effects of possible variations in gas mileage on your answer. Gasoline is a complex mixture of hydrocarbons. In your calculations, assume that gasoline is octane (molecular formula C8H₁8) and that it is burned completely to CO₂ and H₂O in the engine of your car. Also assume that the car averages 26.4 miles per gallon and that the density of octane is 0.703 g cm-3. Reduction in pounds of CO₂ released = lbarrow_forward
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