Chemical Reactions Flashcards
Define enthalpy
The H Heat contained in a system
Identify whether the enthalpy of a reaction would be positive or negative, based on:
Energy diagram
Temperature change
/\H > 0 = positve reaction and requires energy
/\H < 0 = negative reaction and relases energy
Define /\H
Change in enthalpy during a chemical reaction
H products - Hreactants
Draw an energy diagram from:
Exothermic reaction
Endothermic reaction
If it takes less energy to break apart bonds than released when forming new bonds then the reaction will release more energy than required - causing an increase of thermal energy in the surroundings causing an exothermic reaction, where the products are less than the reactants.
If it takes more energy to break apart bonds than released when forming new bonds then the reaction will require more energy than it releases. - causing a decrease in thermal energy in soundings as the reaction absorbs the heat, making it endothermic.
Describe how energy changes during a chemical reaction; in terms of chemical bonds breaking and reforming
To break a bond energy is required
When a chemical bond is formed, energy is released
Combustion
C H + O = CO2 + H2O
Synthesis
A + B = AB
Decomposition
AB = A + B
Single Replacement
AB + C = AC + B
Double Replacement
AB + CD = AD +CB
Acid-Base Neutralization
Acid + Base = H + OH + salt
Law of conservation of Mass:
Total mass in a closed system does not change during a chemical reaction
Closed system
Nothing can enter or leave
Open system
Things can enter and leave
Acid
below 7
Base
above 7
Equivalence point
when acid and base reaction becomes neutral
standardization
determining the concentration of a solution by titration
endpoint
when the indicator changes color
Indicator
a chemical whose color changes at different pH levels.
pH
scale used to determine the acidity and basicity of a solution
What is neutral?
water and salts, NaCl, H2O
Define titration and identify the purpose of the procedure:
a chemical analysis method to quantitatively determine the concentration of a solution
- the unknown concentration solution is reacted with a solution of known concentration
- color change is used to determine the endpoint of the reaction
Why perform a titration?
to verify the concentration of a solution that has been created