Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
1) balance the following chemical equation for the reaction of hypothetical elements X, Y, and Z.
_X3Y6Z2 + _Z2 -> _XZ2 + _Y2Z
2) The solubility of the hydroxide of a hypothetical metal, Me, in water is 132.97 g MeOH per 54.44 mL water. Calculate the amount of water in mL needed to dissolve 62.75 g of MeOH.
Me: 68.32 g/mol
O: 15.999 g/mol
H: 1.00784 g/mol
3)The reaction of hypothetical elements: A, B, C, D, and E, follows the molecular equation:
AB2(aq) + CDE(aq) -> AE(s) + CB(aq) + DB(aq)
4) Assuming that all aqueous compounds would fully dissociate, indicate the element/s that would form spectator ions in the subsequent total ionic equation.
Note: Write the element/s and not the ion/s. Write the element/s in alphabetical order and separate multiple answers by a comma (ex. M, N, O, P, Q)
Which element/s form spectator ions?
5) Ammonia is reacted with phosphoric acid in a neutralization reaction. Indicate the ion/s that are spectator ions in the total ionic equation of this reaction.
Note: Write the ion/s with the correct charge/s and not the element/s. Write the ion/s in alphabetical order and separate multiple answers by a comma (ex. M3+, N2+, O1+, P1-, Q2-)
Which ion/s are spectator ions?
6) Barium sulfate is formed from reacting barium hydroxide and sulfuric acid. Indicate the ion/s that are spectator ions in the total ionic equation of this reaction.
Note: Write the ion/s with the correct charge/s and not the element/s. Write the ion/s in alphabetical order and separate multiple answers by a comma (ex. M3+, N2+, O1+, P1-, Q2-)
Which ion/s are spectator ions?
7) A chemical compound containing hypothetical elements Av, Bw, Cx, Dy, Ez has mass percentages of 18.024% Av, 9.752% Bw, 45.407% Cx, 9.210% Dy, and 17.607% Ez. Determine the molecular formula if the molar mass of the compound is 1556.13 g/mol.
Atomic Mass:
Av: 18.25 g/mol
Bw: 4.32 g/mol
Cx: 26.82 g/mol
Dy: 8.16 g/mol
Ez: 12.48 g/mol
Note: Write the answer in this format: Av1Bw2Cx3Dy5Ez5. 1, 2, 3, 4, and 5 are sample answers
What is the molecular formula of the compound?
8) An acid, HEl, is formed from a hypothetical element, El, and a subsequent aqueous solution is created with the acid and water. The solution is measured to be 27.35% HEl by weight. Calculate the mol % of the acid in the solution.
Atomic Mass:
H: 1.00784 g/mol
O: 15.999 g/mol
El: 168.7549 g/mol
14) Lead (II) nitrate is reacted with sodium iodide. Calculate the number of Pb2+ ions required to form 0.83 g of precipitate. Write the balanced molecular, total ionic, and net ionic equations of the reaction.
Atomic Mass:
Pb: 207.2 g/mol
N: 14.0067 g/mol
O: 15.999 g/mol
Na: 22.989769 g/mol
I: 126.90447 g/mol
Note: Use scientific notation with the format (n)e(x) where n = number and x = exponent (Example: 6.022e23 for 6.022 x 1023)
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
