8. An etching solution for silicon wafers is made up of four parts (by volume) of concentrated hydrofluoric acid to one part concentrated nitric acid to three parts concentrated acetic acid. The hydrofluoric acid is 49% (by mass) HF, and has s specific gravity of 1.198; the nitric acid is 70% HNO3, with a specific gravity of 1.413, and the acetic acid is pure CH3CO₂H with a specific gravity of 1.049. a. How many liters of each acid will be required to make up 100kg of etching solution? b. What is the molarity (moles per liter) of HF and HNO3 in the etching solution?

A mixture of gases has the following composition by mass (kg): Methanol Ethanol Propanol Water CH3OH C₂H5OH C3H7OH H₂O 2.00 80.0 5.00 20.0 a) What is the mixture composition in mass fractions? b) What is the mixture composition in mole fractions? Atomic masses (g/mol) are: 1, 12, and 16 for H, C, and O, respectively. c) What is the average molecular weight of this mixture? d) What is the mole fraction of propanol if all of the water is removed?

10.73 The normal melting point of benzene, C,H, is 5.5°C. For process of melting, what is the sign of each of the fol- lowing? (a) AH°, (b) AS°, (c) AG° at 5.5°C, (d) AG° at 0.0°C, (e) AG° at 25.0°C the

1)For Magnesium (Mg) with a HCP crystal structure. 1a) Show volume of the unit cell given by 6√3R³c. 1b) With the atomic radius of 0.160 mm and a density of 1.74 g/cm³ for Mg, Calculate the c/a ratio of the unit cell.