Methane combusts according to the following thermochemical equation: CH4 (g) +2O2 (g) - CO2 (g) + 2H2O(I) AH = -891 kJ
If 25 g of methane combusts, how much energy is released in the reaction?
(Show all work and answer with the correct significant figures and units.)
CH4(g) + 202(g) --> CO2(g) + 2H2O(g)deltaH = -891 kJ/mol.
Multipliedby2: = - 1780.8.4k) multipled by ZAH=-
I= -445.2kJ
AH°rxn = [2AHºf(CO2) + 3AHºf(H20)]-[AH°f(C2H5OH) + 3AH° S(02)] = [2( - 393.5kJ).+31 - 2
41.8)] - [ - 277.7) + 3(0)]= -1234.7kJ

Which of the following statements is not true? • a. covalent compounds have low melting and boiling points. • ob. covalent bonds between atoms of a compound are relatively weak compared to bonds between molecules. • c. covalent bonds occur between nonmetals. • d. covalent compounds are often gases or liquids.

Darla claims that the first periodic table developed by mendeleev was not completely accurate, so it is not useful at all. harmony argues that it establish the periodic table we use today, making it more credible. who is correct and why? darla is correct, because a model that has any mistakes should be thrown out. darla is correct, because a good model would not need to change. harmony is correct, because mendeleev’s model had all of the information correct in the first version. harmony is correct, because mendeleev’s model made predictions that came true.

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.