Chemical tests Flashcards
What is the definition of chemical analysis?
Chemical analysis is the process of determining the composition of a substance.
True or False: Chemical analysis can only be qualitative.
False
What does qualitative analysis determine?
Qualitative analysis determines the presence or absence of particular substances.
What does quantitative analysis measure?
Quantitative analysis measures the amount or concentration of a substance.
Fill in the blank: The process of separating mixtures into their components is called ______.
fractionation
What is chromatography used for?
Chromatography is used to separate and identify different components in a mixture.
What is the purpose of a standard solution in titration?
A standard solution is used to determine the concentration of an unknown solution.
True or False: A titration can be used to find the pH of a solution.
True
What is a precipitate?
A precipitate is an insoluble solid that forms when two solutions are mixed.
Which method can be used to determine the purity of a substance?
Melting point determination can be used to assess purity.
What is the role of a pH indicator in chemical analysis?
A pH indicator shows the acidity or alkalinity of a solution.
Fill in the blank: In chromatography, the mobile phase is usually a ______.
liquid or gas
What is the Rf value in chromatography?
The Rf value is the ratio of the distance traveled by the compound to the distance traveled by the solvent front.
True or False: A higher Rf value indicates a more polar substance.
False
What is the first step in performing a titration?
The first step is to measure a known volume of the solution using a pipette.
What does the term ‘end point’ mean in titration?
The end point is the stage in a titration where the reaction is complete, indicated by a color change.
What is the significance of calibration in analytical chemistry?
Calibration ensures that the measurements taken are accurate and reliable.
Fill in the blank: A spectrophotometer measures the ______ of light absorbed by a solution.
intensity
What is the purpose of a blank solution in spectrophotometry?
A blank solution is used to zero the instrument and eliminate background noise from the measurements.
True or False: The greater the concentration of a solution, the more light it will absorb.
True
What is the law that relates absorbance to concentration?
Beer-Lambert Law
What is an alkali?
An alkali is a soluble base that releases hydroxide ions (OH-) in solution.
Fill in the blank: Acid-base reactions often produce ______ and ______.
water; salt
What is the difference between strong and weak acids?
Strong acids completely dissociate in water, while weak acids only partially dissociate.
True or False: All metal oxides are bases.
True
What is a titration curve?
A titration curve is a graph that shows the change in pH as a titrant is added.
Fill in the blank: The pH scale ranges from ______ to ______.
0; 14
What is the main purpose of using a buffer solution?
A buffer solution resists changes in pH when small amounts of acid or base are added.
What is the chemical formula for hydrochloric acid?
HCl
What is the main component of vinegar?
Acetic acid
True or False: All salts are neutral.
False
What is the method used to determine the concentration of an unknown acid using a base?
Titration
Fill in the blank: A solution with a pH less than 7 is considered ______.
acidic
What does the term ‘dilution’ refer to?
Dilution refers to the process of reducing the concentration of a solute in a solution.
What is the effect of temperature on the solubility of most solids in liquids?
Generally, solubility increases with temperature.
Fill in the blank: The process of heating a solution to evaporate the solvent is called ______.
evaporation
What is the principle behind gravimetric analysis?
Gravimetric analysis involves measuring the mass of a substance to determine its concentration.
True or False: All chemical reactions are reversible.
False
What is a limiting reactant?
The limiting reactant is the reactant that is completely consumed in a chemical reaction, limiting the amount of product formed.
Fill in the blank: The process of determining the molecular weight of a compound is called ______.
molar mass determination
What is the significance of using indicators in chemical analysis?
Indicators help to visually represent changes in pH or concentration during a reaction.
What is the formula for calculating concentration?
Concentration = Amount of solute / Volume of solution
