Chapter 6: Ions: Charged Particles in Solution Flashcards
How are acids/bases used in food science?
- Food preservation
- Wine, cheese, bread making
Define ionization.
Ionization is the process of forming ions.
How does H3O+ form?
H atom breaks away and bonds with H2O
How does OH- form?
H atom remaining in the OH group shares its electron with the O atom
What chemical compounds are used to define acids/bases?
H+, H3O+, OH-
Define acids.
Acids produce H+ or H3O+ in water-based solutions and have a positive charge
Define bases.
Bases produce OH- in water-based solutions and have a negative charge
Define Bronsted-Lowry’s theory.
- Acids/Bases separate in H2O to form ions
- Acids: proton donors
- Bases: proton acceptors
- Acids and Bases react together to produce a neutral product
Define Lewis’s theory.
- Described in terms of electrons
- Bases donate electrons
- Acids accept electrons
Name two methods to identify acids and bases.
1) Sensory Evaluation
2) Organic Dyes
How do bases feel?
Slippery
How do acids/bases taste?
Acids: sour
Bases: bitter
What colour does Litmus paper become for bases? And acids?
Acids: red
Bases: blue
How does a base affect a green vegetable?
Green vegetables turn brighter if a base is added
Name the 3 ways to measure acids and bases.
1) pH scale
2) Titration
3) Indicators/Organic Dyes
What does the pH scale measure?
The degree of (H+) or (H3O+) ions present in a solution
What do indicators do?
Demonstrate the degree of acidity of a solution through colour change
How does titration work?
- Adding an acid (known pH) to an unknown base or the opposite and observe for a colour change
What do we need to calculate for a titration?
When the colour changes, calculate how many acid molecules it took to neutralize the base molecule
Define the endpoint/equivalence point.
Where neutralization occurs (acid/base molecules are equal)
What does titration require?
Knowing the volume and concentration of a solution
What is a mole?
Avogadro’s number of particles of any substance
What is molarity?
moles/L
Name some roles of buffers.
- Maintaining blood pH
- Coating aspirin (helps digestion and prevents damage to the digestive system)
What are Tums?
Antiacids -> neutralize acids for heartburn
What can a more basic stomach lead to?
++ chances of contaminating substances to survive
What is a great way to preserve food?
Low pH
What is botulism?
Caused by a toxin that affects low-acid foods with a pH above 4.6 (dealdy)
When does yeast grow? Mold?
Yeast: 4.0-7.0
Mold: 2.0 to 8.5
How do salts work to preserve food?
Dehydration
What does pH affect in baking?
Colour, flavour, texture
What is a chemical leavening agent?
Acid and a base that neutralizes batters and doughs to lighten or aerate baked products
How does baking soda work?
Salt base that needs an acidic ingredient to produce CO2 for leavening
How does baking powder work?
Leavens when liquid is added and again when the mixture is heated
What is baking powder made of?
Baking soda, dry acids and a filler
Give an example of how pH affects angel food cake
Acids are added to angel food cake to increase the white color
How does pH affect chocolate cake?
Chocolate cakes have a deeper, darker colour and smoother flavour if the batter is more basic
What happens to the pH of eggs over time? Why?
Eggs become more basic in storage as CO2 escapes through the egg shell
Mousse, soufflés and meringues need fresh eggs, why?
Need fresh eggs because their thicker egg whites trap more air
What happens when fruit matures?
Acids develop that improve juice quality, affect colour, and increase sugar content
Why do we need to test the pH of fruit?
Helps determine the ideal harvest time
What happens to red cabbage when it is cooked in acidity? Alkalinity?
Acid: red
Alkaline: bluish purple
What does pH stand for?
power of Hydronium ions
Are these substances acidic or basic?
Saliva, stomach, pancreatic juice, bile, blood
Saliva: acidic Stomach: acidic Pancreatic juice: basic Bile: basic Blood: basic
How can low-acid foods be preserved? How will it change the food?
Pickling, changes texture and flavour
