Oxygen $\left(\mathrm{O}_{2}\right) \text { at } 25^{\circ} \mathrm{C},$ 100 kPa enters a compressor operating at steady state and exits at $260^\circ C,$ 650 kPa. Stray heat transfer and kinetic and potential energy effects are negligible. Modeling the oxygen as an ideal gas with k = 1.379, determine the isentropic compressor efficiency and the work in kJ per kg of oxygen flowing.

Refrigerant 134a is the working fluid in an ideal vaporcompression refrigeration cycle operating at steady state. Refrigerant enters the compressor at 1 .4 bar, $-12^{\circ} \mathrm{C},$ and the condenser pressure is 9 bar. Liquid exits the condenser at $32^\circ C.$ The mass flow rate of refrigerant is 7 kg/min. Determine a. the compressor power, in kW. b. the refrigeration capacity, in tons. c. the coefficient of performance.

As stated in the chapter, potassium superoxide $\left(\mathrm{KO}_2\right)$ is a useful source of oxygen employed in breathing equipment. Calculate the pressure at which oxygen gas stored at $20^{\circ} \mathrm{C}$ would have the same density as the oxygen gas provided by $\mathrm{KO}_2$. The density of $\mathrm{KO}_2$ at $20^{\circ} \mathrm{C}$ is $2.15 \mathrm{~g} / \mathrm{cm}^3$.

An engineer has proposed mixing extra oxygen with normal air in internal combustion engines to control some of the exhaust products. If an additional 5 percent (by volume) of oxygen is mixed with standard atmospheric air, how will this change the mixture's molecular weight?

Ammonium nitrate reacts explosively upon heating to form nitrogen gas, oxygen gas, and gaseous water. Write a balanced equation for this reaction and determine how much oxygen in grams is produced by the complete reaction of $1.00 \mathrm{~kg}$ of ammonium nitrate.

A beam of singly ionized (1+) oxygen atoms is sent through a mass spectrometer. The values are $B=7.2 \times 10^{-2} \mathrm{T}, q=1.60 \times 10^{-19} \mathrm{C}$, r=0.085 m, and V=110 V. Find the mass of an oxygen atom.

The average oxygen content of arterial blood is approximately 0.25 g of O$_2$ per liter. Assuming a body temperature of 37 degree celcius, how many moles of oxygen are transported by each liter of arterial blood? How many milliliters?

An atom of carbon and an atom of element Z together have a mass of $6$ amu less than double the mass of an atom of oxygen. If an atom of oxygen has a mass of 16 amu and the mass of an atom of carbon is $12$ amu, what is the mass of an atom of element Z?

Fish breathe the dissolved air in water through their gills. Assuming the partial pressures of oxygen and nitrogen in air to be 0.20 atm and 0.80 atm, respectively, calculate the mole fractions of oxygen and nitrogen in water at 298 K. Comment on your results.

A residential heat pump system operating at a steady state is shown schematically in the given figure. Refrigerant 134a circulates through the components of the system, and property data at the numbered locations are given in the figure. The mass flow rate of the refrigerant is $4.6 \mathrm{~kg} / \mathrm{min}$. Kinetic and potential energy effects are negligible. Find

(a) rate of heat transfer between the compressor and the surroundings, in $\mathrm{kJ} / \mathrm{min}$.

(b) the coefficient of performance.

As stated in the chapter, potassium superoxide $\left(\mathrm{KO}_2\right)$ is a useful source of oxygen employed in breathing equipment. Calculate the pressure at which oxygen gas stored at $20^{\circ} \mathrm{C}$ would have the same density as the oxygen gas provided by $\mathrm{KO}_2$. The density of $\mathrm{KO}_2$ at $20^{\circ} \mathrm{C}$ is $2.15 \mathrm{~g} / \mathrm{cm}^3$.

Analyzing Data A mole of a certain compound contains 207.2 g of lead and 32.00 g of oxygen. Without doing any calculations , tell whether a formula unit of the compound contains more atoms of lead or more atoms of oxygen. Explain.

Consider a two-stage turbine operating at steady state with reheat at constant pressure between the stages. Show that the maximum work is developed when the pressure ratio is the same across each stage. Use a cold air-standard analysis, assuming the inlet state and the exit pressure are specified, each expansion process is isentropic, and the temperature at the inlet to each turbine stage is the same. Kinetic and potential energy effects can be ignored.

A mass spectrometer is being used to separate common oxygen- $16$ from the much rarer oxygen-$18$, taken from a sample of old glacial ice. (The relative abundance of these oxygen isotopes is related to climatic temperature at the time the ice was deposited.) The ratio of the masses of these two ions is $16$ to $18$ , the mass of oxygen- $16$ is $2.66 \times 10^{-26} \mathrm{~kg}$, and they are singly charged and travel at $5.00 \times 10^6 \mathrm{~m} / \mathrm{s}$ in a $1.20 \mathrm{~T}$ magnetic field. What is the separation between their paths when they hit a target after traversing a semicircle?