Chemistry of Powders

Powders

• Sodium Acetate: White, soluble in water, pH 8, negative Iodine test (doesn't turn black), vinegar odor with HCl.
• Sand: Insoluble in water, pH 6, negative Iodine test, vinegar odor with Iodine, no reaction with HCl.
• Calcium Carbonate: White, insoluble, pH 7-8, negative Iodine test (color like mustard/peanut butter), fizzes with HCl.
• Ascorbic Acid: White, soluble in water, pH 2, clears iodine, no reaction with HCl.
• Salt: Soluble, pH 6-7, negative Iodine test, no reaction with HCl.
• Sugar: Similar to salt, but less square-shaped grains.
• Flour: Insoluble in water, pH 6-7, positive Iodine test (iodine clumps), no reaction with HCl.
• Cornstarch: Turns into oobleck with water, pH 6-7, turns black with Iodine, no reaction with HCl.
• Gelatin: Light yellow grains, swells with water, pH 6, negative Iodine test, no reaction with HCl.
• Alka-Seltzer: White, soluble in water, pH 6-7, fizzes with Iodine and all other mixtures, including HCl.
• Yeast: Tan pellets, insoluble in water, pH 7, no reaction with HCl.
• Baking Soda: Soluble, pH 8, red-brown with Iodine, very fizzy with HCl.
• Gypsum: White, insoluble in water, pH 6, negative Iodine test, no reaction with HCl.

Liquids

• Lemon Juice: Cloudy yellow, pH 2-3, negative Iodine test.
• Rubbing Alcohol: Clear, pH 6, sweet smell, negative Iodine test.
• Ammonia: Cloudy after shaking, pH 10-11, strong smell, negative Iodine test.
• Vinegar: Clear, pH 2-3, negative Iodine test.
• Water: pH 7, negative Iodine test.
• Hydrogen Peroxide: Clear, pH 6, no scent, bubbles with Iodine.

Metals

• Aluminum: Gray, light, dull, no reaction with water, slight fizz with HCl, not magnetic.
• Copper: Heavy, no reaction with water or HCl, not magnetic.
• Iron: Black, heavy, no reaction with water, fizzes with HCl, magnetic.
• Tin: Gray, sometimes yellowish, light, shiny, no reaction with water, fizzes with HCl.
• Zinc: Gray, heavy, no reaction with water, fizzes with HCl.
• Magnesium: Gray, light, fizzes with water after time, fizzes with HCl, often steams with HCl, strong odor.

Hair

• Hair Structure: Composed of cuticle (outer overlapping scales), cortex (pigment layer), and medulla (central core).
• Scale Types: Coronal, Spinous, Imbricate.
• Medulla Variations: Humans generally have less than ⅓ medulla, while other animals can have more.
• Root Information: DNA location, reveals pulling/falling out.

Fibers

• Burn Test Differences (Natural vs. Synthetic): Natural fibers have characteristic smells and forms of ash production along with extinguishing. Synthetic fibers often produce beads, smolder, and may melt during the burning process.
• Wool: Burns like burning hair, small flame, brittle ash, self-extinguishing.
• Silk: Burns like burning feathers, calm flame, no smoldering, black bead forms, and crumbles, self-extinguishing.
• Cotton: Burns like burning paper, amber/yellow flame, greyish ash, continues to burn after removal from flame.
• Linen: Burns like burning grass, yellowish flame, burns constantly, sparks, continues to burn after removal.
• Nylon: Burns with celery smell, hard orange bead forms, self-extinguishing.
• Acrylic: Pungent smell, rapid burning, hard black bead forms, partially crushable, continues to melt after removal.
• Polyester: Sweet chemical taste, rapid burning, black bead forms that can't be crushed, continues to burn after removal.
• Rayon: Burns like burning wood, rapid burning, no ash, continues to burn after removal.
• Crunch Test Differences: Natural fibers wrinkle and crease, synthetic fibers do not or slightly wrinkle.

Fingerprints

• Fingerprint Patterns: Arches (simplest, no deltas), Tented arches (similar to arches, with a central spike), Loops (most common, one delta), Whorls (two deltas, complete circle), Accidental (combination of patterns).
• Delta Definition: Where ridges converge to form a triangle
• Core Definition: The center of the fingerprint
• Fingerprint Types: Patent (visible), Plastic (indented), Latent (invisible).

Soil

• Soil Types: Peaty, loamy, sandy, clay, chalky, silty.
• Color Correlations: Dark brown (loamy), darker brown (nearly black) (peaty), lighter than loamy (silty), similar to sand (sandy), lighter than others (clay), similar to limestone (chalky)
• Soil Composition Chart: A chart allows visualization of relative percentages of sand, clay, and silt to determine soil type.
• pH Test: Different soils have different ranges of pH, allowing different soils to be separated based on their pH value.
• Soil Diameter: Clay < Silty < Sandy.

Spatters

• Blood Spatter Velocity: Determined by diameter.
  • Low (4 mm or more): Accidental wounding.
  • Medium (2-4 mm): Beating, stabbing.
  • High (2 mm or less): Gunshot, bombing.
• Blood Spatter Direction: Determined by the direction of the tail of the spatter.

DNA

• DNA Structure: Double helix shaped molecule; made up of atoms forming a ladder.
• DNA Function: Codes for traits and qualities of living organisms.
• Amino Acids: Building blocks of life, 20 different types.
• Amino Acid Formation: Combine to form proteins
• Protein Function: Cells, tissues, organs, living organisms
• DNA's role in forming proteins: DNA provides the instructions telling amino acids how to form proteins correctly.
• Nucleotides: Basic building blocks of DNA, four types: adenine (A), thymine (T), guanine (G), and cytosine (C).
• Base Pairs: A with T, and G with C
• RNA: Partial copies of DNA, crucial for delivering instructions to amino acids.
• Ribosomes: Read RNA codes, assemble amino acids into proteins.
• Protein Formation: Ribosomes follow RNA’s instructions to produce strings of amino acids that fold into correct 3D structures.

Nucleotides

• Nucleotide Composition: Five-carbon sugar (pentose), phosphate group, nitrogenous base.
• Pentose Sugar Variations: Ribose in RNA, Deoxyribose in DNA (one less oxygen).
• Nitrogenous Bases: Specific to DNA (adenine, guanine, cytosine, thymine) and RNA (adenine, guanine, cytosine, uracil).