Chapter 8: Chemical Reactions and Thermochemistry

Question 1

types of reactions

Answer 1

• combination/synthesis
• decomposition
• single replacement/single displacement (AB+C–>AC+B)
• double replacement/ double displacement (precipitation, acid-base, reaction that gives off gaseous compound)
• combustion (CxHy + O2 —> CO2 + H2O)
• redox

Question 2

heat of formation

Answer 2

• number of kJ absorbed when the ONE mole of compound is formed (positive means heat absorbed and negative means heat given off)
• if ΔH is a large negative value, then difficult to decompose (put more energy in)
• standard heat (enthalpy) of formation is final minus initial of all elements not in their standard state (at 25 * C and 1 atm)

Question 3

activity series (generally)

Answer 3

• most reactive: alkali metals and alkaline earth metals
• 2nd most reactive: first row of transition metals, Al, Cd
• least reactive: Ag, Au, Pt

Question 4

solubility rules

Answer 4

-any compound with NH4+, nitrate, salt with group 1 elements, acetates, bicarbonates, chlorates are soluble

Question 5

hydrolysis reaction

Answer 5

-opposite of neutralization (acid/base) reactions: salt and water react to form acid and base

Question 6

entropy (ΔS)

Answer 6

-measure of disorder

Question 7

heat of combustion

Answer 7

-heat released by the combustion of one mol of a reactant

Question 8

First Law of Thermodynamics

Answer 8

• energy i neither created nor destroyed

- allows for the use of Hess’s Law

Question 9

standard enthalpy of a reaction

Answer 9

ΔHoreaction=∑nΔHof(products)−∑nΔHof(Reactants)