Chapter 1 Flashcards
Quality of Analytical Measurements
Define Analytical Chemistry.
Analytical Chemistry is the study of the chemical composition of materials.
What does qualitative analysis reveal?
The identity of the elements and compounds in a sample.
What does quantitative analysis reveal?
The amount of each substance in a sample.
What is an analyte?
Element or compound determined in a sample.
List the typical steps in quantitative analysis.
- Select method
- Measure property X
- Calculate results
- Acquire sample
- Eliminate interferences
- Estimate reliability
- Process sample
- Check solubility
- Report results
What are the four main types of analytical methods?
- Gravimetric methods
- Volumetric methods
- Electroanalytical methods
- Spectroscopic methods
How can sample size and analyte concentration be classified?
Based on the size of the sample and the analyte concentration.
What is the value of 1 mole?
6.02214 x 10^23 particles.
What is the molar mass of a substance?
The mass of 1 mol of a substance.
What does molarity express?
The amount of solute (in moles) divided by the volume of solution (in litres).
What is the formula for calculating molarity?
M = n / V
What is the difference between analytical concentration and equilibrium concentration?
Analytical concentration is the total number of moles in L of solution; equilibrium concentration is the molar concentration at equilibrium.
How can concentrations be expressed in terms of percent?
Common methods include weight/weight percent, volume/volume percent, and weight/volume percent.
Define accuracy in measurements.
Accuracy indicates the closeness of the measurement to the true or accepted value.
What are the three types of errors in analytical measurements?
- Gross errors
- Systematic errors
- Random errors
What is relative standard deviation (RSD)?
When multiplied by 100%, it is called the coefficient of variation (CV).
What does precision describe?
The reproducibility of measurements.
What do significant figures indicate?
The level of certainty in a measurement.
True or False: All analytical measurements carry a level of uncertainty.
True
