Studied by 2 people
What does aqueous (aq) mean?
Dissolved in water
True or False: Given ideal conditions, it is possible for reactions to yield 100%
False
Why is the mole ratio used?
Because moles of reactants do not equation moles of products and because moles cannot be measured but grams can
What is equal on both sides of a reaction?
Atoms of reactants and atoms of products and mass of reactants and mass of products
What does the Law of Conservation of Matter state?
Matter cannot be created or destroyed
Why do we balance equations?
Chemical equations must be balanced to obey the law of conservation of matter
What are the 5 types of chemical reactions?
Combustion, Double Displacement, Single Displacement, Synthesis, Decomposition
What is a combustion reaction?
hydrocarbon burning in oxygen to produce CO2 and H2O
Precipitation reactions are what type of reaction?
Double displacement reaction
When compounds are dissociated what happens to the coefficient?
Coefficients are distributed to each term and the diatomic subscripts are turned into coefficients
What are redox reactions?
When there is a net movement of electrons within a reaction
What is oxidation?
Loss of electrons
What is reduction?
Gain of electrons
What is the oxidizing agent?
Substance that is reduced (causes oxidation)
What is the reducing agent?
Substance that is oxidized (causes reduction)
True or False: Fractions can be used to balance redox half reactions
True
True or False: Oxidation number rules are listed in order of importance
True
Sign before number
Oxidation
Sign after number
Charge
What are the 3 types of redox reactions?
Combination, Decomposition, and Single Displacement
How can decomposition redox reactions occur?
They can be thermal (occurring by heat) or electrolytic (occurring by the use of current
What is an acid/base neutralization reaction?
Double Displacement reaction without a precipitate
What is the Bronsted Lowry definition of an acid?
H+ proton donor
What is the Bronsted Lowry definition of a base?
H+ proton acceptor
What are the 7 strong acids?
HCl, HBr, HI, HNO3, H2SO4, HClO3, HClO4
What are strong bases made of?
Group1+Hydroxides(OH) and Group2+Hydroxides(OH) [except Mg and Be]
What do acid base reactions produce?
Salt and water
What are acid/base titrations used for?
Used to standardize or find the concentration of an unknown acid or base
What solution goes in the buret during acid/base titrations?
Acid/base with a known concentration
What solution goes in the beaker during acid/base titration?
Acid/base with unknown concentration with a specific amount
What is equal during the equivalence point of an acid/base titration?
mol H+=mol OH- (moles of acid=moles of base)
What is the difference between an endpoint and an equivalence point?
There is a slight (insignificant) excess of what is being titrated from the buret in the beaker at the endpoint, while at the equivalence point the chemical reaction comes to an end
How do we in a lab know that the reaction is complete during an acid/base titration?
An indicator (phenolphthalein) changes color indicating the endpoint is reached
What are the steps for calculating quantities for reactions?
Write chemical equation 2. Balance chemical equation 3. Calculate the moles given 4. Use the mole ratio from balanced equation 5. Convert moles to grams for what is needed
How do you determine the limiting reactant?
Convert reactants to moles 2. Divide by coefficient 3. Reactant with smaller number is limiting
What is the percent yield formula?
(actual/theoretical)*100
What is the percent error formula?
[(actual-expected)/expected]*100
How do you calculate how much excess reactant is reacted?
Multiply the limiting reactant by the molar ratio
How do you calculate how much excess reactant is left over?
Subtract excess given yield by calculated yield
What is thermodynamics?
The study of energy
What is thermochemistry?
The study of heat flow in physical/chemical change?
What are examples of physical changes in thermochemistry?
Transferring energy, changing states of matter, making solutions
What is an example of a chemical change in thermochemistry?
Chemical reactions
What is the difference between a system and its surroundings?
A system is a point of reference or the part of the universe being studied, while the surroundings are everything not in the system
What is the relationship between J and kJ?
1000 J=1kJ
What is the SI unit for energy?
J
What is the relationship between cal and J?
4.184J=1 cal
How much energy does it take to raise 1 degree of 1 gram of water?
1 calorie or 4.184 J
What do “+” and “minus” indicate in thermodynamics?
Direction of energy flow
Why is it vital to define a system in thermodynamics?
To determine which sign to use and the flow of energy
What is the difference between “minus” and “+” signs in thermodynamics?
“minus” means energy is flowing out of a system and energy is released, while “+” means energy is flowing into a system and energy is absorbed
What is a state function?
A property whose value does not depend on the path taken to reach that specific value
True or False: ∆Hreaction=0
False, ∆Reaction=∆Products
What is enthalpy?
A thermodynamic quantity equivalent of the total heat of a reaction or system
Why is the change in enthalpy discussed instead of just enthalpy?
It is easier to measure the change of enthalpy than just enthalpy
What is true in exothermic reactions?
H of reactants > H of products, ∆H < 0, usually hot because energy is released
What is true in endothermic reactions?
H of products > H of reactants, ∆H > 0, usually cold because energy is absorbed
What is on the Y axis of enthalpy diagrams?
Enthalpy, ∆H
How do graphs of enthalpy diagrams of endothermic and exothermic diagrams differ?
Reactants go on top and products go on the bottom for exothermic processes, while products go on top and reactants go on the bottom for endothermic reactions
True or False: The enthalpy (∆H) goes on the products side for endothermic reactions
False, ∆H goes the products side for exothermic reactions and goes on the reactants side for endothermic reactions
What is the specific heat capacity and its symbol?
c, heated needed to raise 1 gram of a substance by 1 kelvin or celsius
What is q?
Heat transfer
What is the q equation?
q=mc∆T
What determines the sign of q and makes it “+” or “minus”?
When does q give off heat?
When q is negative
When does q absorb heat?
When q is positive
What are the 2 types of calorimeters?
Constant P (coffee cup) and Constant V (bomb calorimeter)
True or False: Temperature=energy
False, Temperature is measured in C/K, energy is measured in J/cal
What are calorimeters used for?
To determine the specific heat capacity of a metal sample
In calorimeters what is always equivalent?
Final temperature of water and final temperature of metal
What does ∆T mean?
Final temperature-inital temperature
What is the relationship between a system and its surroundings?
qin(absorbs heat)=-qout(gives off heat)
How do you calculate how much energy a reaction produces?
Multiple the molar ratio by the ∆H
Define Hess’s Law
Enthalpy of an overall reaction is the sum of the enthalpy of the step reactions that total the reaction, overall enthalpy=sum of step reactions
Why do we use/need Hess’s Law
Most reactions occur in multiple steps
Define Standard Enthalpy of Formation
Change in enthalpy when 1 mole of a substance at standard state is formed from is pure elements under the same conditions
What role does energy play in Standard Enthalpy of Formation
How much energy it takes/gives off when forming 1 mole of given substance
How does Standard Enthalpy of Reaction differ from Standard Enthalpy of Formation?
Standard heat of reaction (Standard enthalpy of reaction) is the sum of the standard heat (enthalpy) of reaction of the products minus the reactants
Why is the unit kJ/mol used for the standard of enthalpy of reaction problems?
Change in enthalpies have been calculated by standard enthalpies of formations, which is measured per mol
Why do moles cancel out when calculating standard enthalpy of reaction problems?
Moles of substance are been multiplied by standard enthalpy of formation, which is measured in kJ/mol
What is the standard enthalpy of formation of mono/diatomic elements?
0 kJ/mol
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Flashcard (111)