1. A sample of gas undergoes a process in which there is both heat and work. The temperature increases while the vol-ume expands. What are the signs of ΔU, Q, and W? What are the relative magnitudes of Q and W? Briefly explain how you determined your answers. 2. For this problem, refer to the attached figure. Starting at T=1250K, 3 moles of a gas undergo a constant volume process in which the internal energy de-creases by 1.37 kJ and the temperature decreases by 10K. What gas is this and why?7A 2C Quiz 8 DL Sec. ____ Name_____________________ __________________ last first for office use onlyI certify by my signature that I will abide by the codeof academic conduct of the University of California. Signature _____________________________Formulas: ΔU = Q+W; Cv = Q/ΔT; ΔEth = (1/2)R(#modes)(#moles)ΔT; R = 8.3 J/mol·K; W= -∫PdV Chapter 3 Applying Particle Models to Matter 55 3-2 Phenomena, Data Patterns, and Kinds of Questions and Explanations Phenomena The particulate nature of matter provides a model that allows explanations of a large range of phenomena that simply cannot be explained without invoking this fundamental idea regarding what matter is. In this chapter much of the focus will be simply developing a basic particle model, Intro Particle Model of Matter, sufficiently far so that, with a Particle Model of Bond Energy and a Particle Model of Thermal Energy it will be possible to develop explanations for many of the empirically determined thermal properties of matter encountered in Chapter 1. Specifically, how do we make sense of the range of thermal and bond energies we encountered in Chapter 1? Data Patterns In addition to the sampling of heat capacity data and heats of fusion and vaporization presented in Chapter 1, we would expect our models to provide us with the capability of explaining the heat capacity values, both at constant pressure and at constant volume for a large range of substances. Several of these data patterns are presented on this and the next page. This first graph shows the constant volume molar heat capacity of several gases from room temperature up to several thousand kelvin. The values of the heat capacities have been divided by the gas constant, R. There are several obvious trends. The monatomic gases have the lowest molar constant-volume heat capacity at 3/2 R and the values are independent of temperature. Diatomic gases seem to have higher values starting at about 5/2 R, while polyatomic gases have significantly larger values, but also a much more pronounced temperature dependence. These are some of the trends our models should enable us to provide explanations for. 9.58.57.56.55.54.5Monatomic gases (He, Ar, Ne, etc.)H2N2Cl2CO2CH4NH330050010002000T