Select all that apply. Considering the following compounds, which two structures represent the same compound? 0 CH3CH₂CH(CH3)CH₂CH₂CH3 CH3(CH₂)3CH(CH3)2

A 19.51 g sample of impure methylamine, which contains 72.58% (by mass) of CH;NH: , is reacted with 30.81 g of pure oxygen gas: 2.1 4CH, NH,(2) + 90,(8) - 4C0,(8) + 10H,0(?) + 2N;(8) 2.1.1 What is the percentage yield of this reaction if 5.54 g of nitrogen gas is collected? 2.1.2 In another experiment, this impure methylamine was used as follows: • An unknown mass of the impure compound is dissolved in enough water to make 500.0 m of solution. • 20 ml of this solution was transferred by pipette to a clean 250 ml volumetric flask and made up to the mark. • The molarity of the CH;NH; in the final solution was determined to be 0.103 M. Determine the mass of CH;NH; present in the original amount of impure compound used make this solution.

1. More than 2000 years ago human cultures figured out a way to produce iron metal from rocks containing iron ores. This iron could be worked by a blacksmith (repeated heating and hammering) to make iron metal pure enough for creating useful tools (even Samurai swords). This direct heating technique was common up until about 200 years ago when people found a better way to obtain iron metal. When hematite, Fe2O3(s), is strongly heated in a blast furnace in the presence of charcoal (carbon), pure iron metal is obtained. Fe2O3() 2 Fe(s) + 3/2 O2 (g) (1) C(s) + O2 (g) → CO2(g) (2) When reaction 1 is coupled to reaction 2, overall chemical equation is Fe2O3() + 3/2 C() 3/2 CO2(g) + 2 Fee) Use the thermodynamic data given below for the following calculations: AG¡ (kJ/mol) | 4H¡ (kJ/mol) | S (J/mol-K) Fe2O3(s) -742.2 -824.2 87.40 Fes) 27.28 CO2(8) -394.36 -393.51 213.74 C (6) 5.74 O2 (2) 205.14 a) Calculate the standard Gibb's free energy change for reaction 1 b) Calculate the standard Gibb’s…

The great French chemist Antoine Lavoisier discovered the Law of Conservation of Mass in part by doing a famous experiment in 1775. In this experiment Lavoisier found that mercury(II) oxide, when heated, decomposed into liquid mercury and an invisible and previously unknown substance: oxygen gas. 1. Write a balanced chemical equation, including physical state symbols, for the decomposition of solid mercury(II) oxide (HgO) into liquid mercury and gaseous dioxygen.   2. Suppose 53.0mL of dioxygen gas are produced by this reaction, at a temperature of 50.0°C and pressure of exactly 1atm. Calculate the mass of mercury(II) oxide that must have reacted. Be sure your answer has the correct number of significant digits.