Electrochemistry

What is an indicator electrode?

Electrode that only reacts with the analyte of interest

What is a reference electrode?

Electrode that generates a stable electrical potential

What is an ion selective electrode (ISE)?

An electrode that selects for ions through transportation of the analyte through a membrane with a carrier molecule

What is osmometry?

measurement of particle concentrations within a specific volume as related to osmotic pressure

What is osmolality?

the number of moles of particles per kilogram of solvent

What is osmolarity?

the number of particles per liter of solution

What is electrochemistry?

the measurement of electrical signals associated with chemical systems within an electrochemical cell

Describe how an electrochemical cell works.

two electrodes (reference and indicator) bridge between a chemical and electrical system

a chemical reaction creates a current that is proportional to the ion concentration in solution

The electrons flow away from the anode (oxidation) and move to the cathode (reduction)

What is potentiometry?

The measurement of the potential difference between two half cells in a solution

Specifically used to measure hydrogen ions as a pH meter

What is coulometry?

the measurement of an electrical charge consumed or produced in an electrochemical reaction

Specifically used to measure chloride ions in a sweat test

What is amperometry?

the measurement of the current response of the electrode system as a result of external potential 

Specifically used to measure oxygen tension in ABG

What are the four colligative properties of osmometry?

1. osmotic pressure

2. boil point

3. freeze point

4. vapor pressure

As solute concentration increases, what happens to the osmotic pressure?

osmotic pressure increases

As solute concentration increases, what happens to the boil point?

boil point increases

As solute concentration increases, what happens to the vapor pressure?

vapor pressure decreases

As solute concentration increases, what happens to the freeze point?

freeze point decreases

Which of the colligative properties are used to measure osmolality?

vapor pressure and freeze point

What is the simple formula to calculate an osmol gap?

measured values - calculated values

What is the normal osmol gap value?

< 10 mOsm/kg

If the osmol gap is over 10, what can it indicate?

toxins or ketone bodies present