1. which of the following is a correctly written thermochemical equation?

nh4cl nh4+ + cl
2c8h18 + 25o2 16co2 + 18h2o, h = 5,471 kj/mol
fe (s) + o2 (g) fe2o3 (s), h = 3,926 kj
--> c3h8 (g) + 5o2 (g) 3co2 (g) + 4h2o (l), h = 2,220 kj/mol
2. how does a phase change affect a thermochemical equation?

it alters the moles of reactants.
--> it can affect the (delta) h value.
it alters the products.
it affects the balance of the equation.

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution.calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.