Chem Cels Flashcards
What element do all organic compounds always contain?
Carbon
Who was the first person to synthesize an organic compound?
Fredrick Wöhler
What are the four classes of biological organic compounds?
- Carbohydrates
- Proteins
- Lipids
- Nucleic acids
What are carbohydrates commonly known as?
Sugars and starches
What is the purpose of indicators in testing for organic compounds?
Indicators react with molecules causing a color change indicating that a substance is present
What is a standard (control) in the context of experimental results?
A known result with which to compare to an experimental result
What color does iodine change to in the presence of starch?
Blackish-purple
What color does Benedict’s reagent change to when heated and sugar is present?
- Green
- Yellowish-orange
- Brick red
What color change indicates the presence of protein when using Biuret reagent?
Lilac or purple
What does a positive result indicate when an indicator is added to a solution?
The corresponding organic compound is present
What does a negative result indicate when an indicator is added to a solution?
The corresponding organic compound is absent
What is pH a measure of?
The strength of acids and bases based on the concentration of hydrogen (H+) and hydroxide (OH-) ions
What is the pH range for acids?
0-6.9
What is the pH of neutral solutions?
7
What is the pH range for bases?
7.1-14
What is the pH of human blood?
7.42
What are buffers?
Substances that resist a change in pH levels
What is the purpose of today’s lab?
To learn how to use indicators to determine the composition and pH of solutions
Fill in the blank: The pH scale ranges from _____ to 14.
0
What common plant indicator will be used to determine pH in today’s lab?
Anthocyanin
