An air compressor is used to charge an initially empty 200-L tank with air up to 5 MPa. The air inlet to the compressor is at 100 kPa, 17$^{\circ} \mathrm{C}$ and the compressor’s isentropic efficiency is 80%. Find the total compressor work and the change in exergy of the air.

The energy necessary to break the ionic bond between a sodium ion and a fluorine ion is 4.99 eV. The energy necessary to separate the sodium and fluorine ions that form the ionic NaF crystal is 9,30 eV per ion pair. Explain the difference qualitatively.

The vertices of a tetrahedron are four vertices of a cube symmetrically chosen so that no two are adjacent. Show that the angle between the vertices of a tetrahedron is $109.5^\circ.$

Air in an automobile tire is initially at −10$^{\circ} \mathrm{C}$ and 190 kPa. After the automobile is driven a while, the temperature rises to 10$^{\circ} \mathrm{C}$. Find the new pressure. You must make one assumption on your own.

A new refrigerant, R-125, is stored as a liquid at −20$^{\circ} \mathrm{C}$ with a small amount of vapor. For 1.5 kg of R-125, find the pressure and volume.

Ammonia, 2 kg, at 400 kPa, 40$^{\circ} \mathrm{C}$ is in a piston/ cylinder together with an unknown mass of saturated liquid ammonia at 400 kPa. The piston is loaded, so it maintains constant pressure, and the two masses are allowed to mix to a final uniform state of saturated vapor without external heat transfer. Find the total exergy destruction (irreversibility) in the process.

Give two examples of industries in which joint costs are found. For each example, what are the individual products at the splitoff point?

On a chilly 10$^{\circ} \mathrm{C}$ fall day a house, with an indoor temperature of 20$^{\circ} \mathrm{C}$, loses 6 kW by heat transfer. What transfer happens on a warm summer day with an indoor temperature of 30$^{\circ} \mathrm{C}$, assuming everything else is the same?

“There’s no reason for me to get excited about the choice between the weighted-average and FIFO methods in my process-costing system. I have long-term contracts with my materials suppliers at fixed prices.” Do you agree with this statement made by a plant controller? Explain.

Determine Q for the reaction $_{3}^{7} \mathrm{Li}+_{1}^{1} \mathrm{H} \rightarrow_{4}^{7} \mathrm{Be}+\frac{1}{0} \mathrm{n}$

(CPA) Choose the best answer. 1. The Cozy Company manufactures slippers and sells them at $10 a pair. Variable manufacturing cost is$5.75 a pair, and allocated fixed manufacturing cost is $1.75 a pair. It has enough idle capacity available to accept a one-time-only special order of 25,000 pairs of slippers at$7.50 a pair. Cozy will not incur any marketing costs as a result of the special order. What would the effect on operating income be if the special order could be accepted without affecting normal sales: (a) $0, (b)$43,750 increase, (c) $143,750 increase, or (d)$187,500 increase? Show your calculations. 2. The Manchester Company manufactures Part No. 498 for use in its production line. The manufacturing cost per unit for 10,000 units of Part No. 498 is as follows: The Remnant Company has offered to sell 10,000 units of Part No. 498 to Manchester for $71 per unit. Manchester will make the decision to buy the part from Remnant if there is an overall savings of at least$45,000 for Manchester. If Manchester accepts Remnant’s offer, $11 per unit of the fixed overhead allocated would be eliminated. Furthermore, Manchester has determined that the released facilities could be used to save relevant costs in the manufacture of Part No. 575. For Manchester to achieve an overall savings of$45,000, the amount of relevant costs that would have to be saved by using the released facilities in the manufacture of Part No. 575 would be which of the following: (a) $30,000, (b)$115,000, (c) $125,000, or (d)$100,000? Show your calculations. What other factors might Manchester consider before outsourcing to Remnant?

$$\begin{matrix} \text{Direct materials} & \text{\$3}\\ \text{Variable direct manufacturing labor} & \text{40}\\ \text{Variable manufacturing overhead} & \text{10}\\ \text{Fixed manufacturing overhead allocated} & \text{21}\\ \text{Total manufacturing cost per unit} & \text{\$74}\\ \end{matrix}$$

A small house kept at 20$^{\circ} \mathrm{C}$ inside loses 12 kW to the outside ambient at 0$^{\circ} \mathrm{C}$. A heat pump is used to help heat the house together with possible electrical heat. The heat pump is driven by a motor of 2.5 kW, and it has a COP that is one-quarter that of a Carnot heat pump unit. Find the actual heat pump COP and the exergy destruction in the whole process.

Consider a large classroom with 90 students on a hot summer day. All the lights with 2.0 kW of rated power are kept on. The room has no external walls, and thus heat gain through the walls and the roof is negligible. Chilled air is available at $15^\circ C,$ and the temperature of the return air is not to exceed $25^\circ C.$ The average rate of metabolic heat generation by a person sitting or doing light work is 115 W (70 W sensible and 45 W latent). Determine the required flow rate of air that needs to be supplied to the room.

An air conditioner on a hot summer day removes 8 kW of energy from a house at 21$^{\circ} \mathrm{C}$ and pushes energy to the outside, which is at 31$^{\circ} \mathrm{C}$. The house has a mass of 15 000 kg with an average specific heat of 0.95 kJ/kgK. In order to do this, the cold side of the air conditioner is at 5$^{\circ} \mathrm{C}$ and the hot side is at 40$^{\circ} \mathrm{C}$. The air conditioner (refrigerator) has a COP that is 60% that of a corresponding Carnot refrigerator. Find the actual COP of the air conditioner and the power required to run it.