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The coldest temperature ever recorded on Earth was
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Chemistry
- 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_forwardInsoluble AgCl(s) precipitates when solutions of AgNO3(aq) and NaCl(aq) are mixed. AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) rH = ? To measure the energy evolved in this reaction, 250. mL of 0.16 M AgNO3(aq) and 125 mL of 0.32 M NaCl(aq) are mixed in a coffee-cup calorimeter. The temperature of the mixture rises from 21.15 C to 22.90 C. Calculate the enthalpy change for the precipitation of AgCl(s), in kJ/mol. (Assume the density of the solution is 1.0 g/mL and its specific heat capacity is 4.2 J/g K.)arrow_forwardExplain why oceanfront areas generally have smaller temperature fluctuations than inland areas.arrow_forward
- Determine 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_forwardA 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_forward
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