Lab Quiz #2 [Thermodynamics + Buffers] Flashcards
What is thermodynamics?
Give an example
- is the flow of energy in living system
- ex. chem. energy (E found in bonds)
State the first law of thermodynamics
Give some examples
energy cannot be created or destroyed; can only be transformed from one state to another
ex. chem energy -> mech. energy
glucose -> muscle energy
State the second law of thermodynamics
With each transformation, energy is lost as heat (not 100% transformed)
all living organisms require continue input of energy
Describe an ENDERGONIC reaction
- requires input of E for rxn to proceed
- products contain more free E than reactants
Describe an EXERGONIC reaction
- release E as rxn proceeds
- product contains less free E than reactants
What type of reaction is this?
e + A + B -> C
endergonic rxn
(reactants are low e, product is high e)
What type of reaction is this?
A + B -> C + e
exergonic rxn
(reactants are high E, product is low E)
If E is released by ________ rxn, it may lead to running the ___________ rxn
exergonic
endergonic
What ΔG sign means an EXERGONIC rxn?
What does it mean? What type of reaction is it?
-ΔG
negative
It means you are releasing E; spontaneous reaction
What ΔG sign means an ENDERGONIC rxn?
What does it mean? What type of reaction is it?
+ΔG
positive
It means you are adding E to reactants; nonspontaneous rxn
Can Rxn #1 run Rxn #2? Why or why not?
Rxn#1: ΔG = -100 cal
Rxn #2: ΔG = 25 cal
Rxn #1 CAN run rxn #2. This is because rxn #1 is releasing 100 cal of energy, and rxn #2 only requires 25 cal of energy to be ran.
What happened to the temperature when KOH was added to water?
What type of reaction? Where did the energy go?
Is ΔG positive or negative?
The final solution temperature increased
Exergonic reaction; there was more energy in the bonds of the reactants than needed to make the product; therefore, when the bonds broke, energy was released in the form of heat (which is why the final solution temperature was warmer)
-ΔG (negative) because energy was released
What happened to the temperature when NH4Cl was added to water?
What type of reaction? Where did the energy go?
Is ΔG positive or negative?
The final solution temperature decreased
Endergonic reaction; the energy in the bonds of the reactants was lower compared to the energy needed to create the product, thus more energy was needed to be inputted into the rxn
+ΔG (positive) because energy was inputted
Describe what happened when barium hydroxide and ammonium thiocyanate were mixed together?
Was the energy found in the bonds of the original reactants greater or less than that found in the final products?
Exergonic or endergonic? Positive or negative ΔG?
The two solids were mixed which led to the transformation of a slush. The final temperature decreased, which means that heat was NOT released. The reaction must have taken in heat which is why the temperature decreased
The energy found in the bonds of the original reactants was less than in the products.
Endergonic reaction; +ΔG (positive)
Define pH
measure of concentration of H ions in a solution in a log scale (power of 10); equals 1 * 10^-7
What numbers on the pH scale indicate if a solution is acidic, neutral, or basic?
acidic - 1
neutral - 7
alkaline/basic - 14
Which ion is measured with a pH meter?
H+ ions
What does it mean if a solution is acidic?
more H+ present than OH-
What does it mean if a solution is basic?
more OH- present than H+
What does it mean if a solution is neutral?
H+ = OH-
What is the normal range for blood pH?
How is this normal range maintained?
7.35 - 7.45
normal range is maintained through buffer; bicarbonate - HCO3
When does acidosis occur?
pH < 7.35
Define buffers
What are some common buffers?
molecules that slow changes in pH by combining with or releasing H+
protein, phosphate, bicarbonate
Write the rxn for the bicarbonate system in blood
H20 + C02 - H2CO3 - H+ + HCO3-
Which way will the reaction run if the blood is too basic?
H20 + C02 - H2CO3 - H+ + HCO3-
basic means more OH- than H+
reaction will run from left to right in order to release H+ ions. this will make the blood less basic and move toward homeostasis
Which way will the reaction run if the blood is too acidic?
H20 + C02 - H2CO3 - H+ + HCO3-
acidic means more H+ than OH-
reaction will run from right to left. bicarbonate will combine with excess H+ ions, which will reduce the acidity of the blood.
What happened when HCl was added to distilled H20?
What happened when HCl was added to a phosphate buffer?
pH decreased in larger increments (became more acidic)
pH still decreased but in smaller increments
What happened when NaOH was added to distilled H20?
What happened when NaOH was added to a phosphate buffer?
pH increased in larger increments (became more basic)
pH still increased but in smaller increments
