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sep 23

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Termini in questo insieme (20)

  • Why is solid water (ice) less dense than liquid water?

    Hydrogen bonds in ice are stable and form a 3D crystal lattice, creating more space between molecules than in liquid water where hydrogen bonds constantly break and reform.

  • What role does ice play in aquatic ecosystems during winter?

    Ice floats on top of lakes, insulating the liquid water below and allowing aquatic organisms to survive underneath.

  • Define solution, solvent, solute, and aqueous solution.

    solution: a liquid consisting of a uniform mixture of 2 or more substances Solvent: dissolving agent; Solute: substance dissolved; Aqueous solution: solution where water is the solvent.

  • How does water dissolve ionic compounds like NaCl?

    Water's positive hydrogen atoms attract negative ions (Cl-), and negative oxygen atoms attract positive ions (Na+), separating the ions in solution.

  • How does water dissolve non-ionic compounds such as sugar?

    Water forms hydrogen bonds with polar regions of the compound, surrounding and dissolving it.

  • What happens when water dissociates into ions?

    Water molecules dissociate into H+ (hydrogen ions) and OH- (hydroxide ions), which affect the reactivity of molecules and pH.

  • What defines an acid and a base in terms of H+ concentration?

    Acid: donates H+ and has higher H+ concentration than OH-; Base: reduces H+ concentration by accepting H+ or releasing OH-.

  • Explain the pH scale and its significance.

    The pH scale ranges from 0 to 14, each unit representing a tenfold change in H+ concentration; pH 7 is neutral with equal H+ and OH-.

  • Why is pH regulation important in the human body?

    Most cells function near pH 7.0; blood pH is about 7.4. Deviations outside 7.0–7.8 can be fatal. Buffers maintain stable pH by accepting or donating H+.

  • What causes ocean acidification and how does it affect coral reefs?

    CO2 absorption lowers ocean pH, increasing bicarbonate ions, which harms coral reef formation and health.

  • Why is carbon essential for life molecules?

    Carbon forms the backbone of organic molecules due to its ability to form four covalent bonds and complex 3D structures.

  • What are isomers in organic chemistry?

    Compounds with the same chemical formula but different structural arrangements, leading to different properties.

  • Give an example of isomers and their significance in pharmacology.

    Butane and isobutane (C4H10) differ structurally; drug isomers like methamphetamine can have very different effects.

  • What are hydrocarbons and where are they commonly found?

    Molecules made of only carbon and hydrogen; major components of fossil fuels and parts of larger molecules like farts.

  • Describe the shape of a methane molecule and its bonding.

    Methane (CH4) has a tetrahedral shape with four single covalent bonds between carbon and hydrogen atoms.

  • What is a carbon skeleton in organic molecules?

    The chain of carbon atoms forming the backbone of an organic molecule.

  • How do double bonds affect the shape of organic molecules?

    Double bonds restrict rotation and change the molecule's 3D shape, affecting its properties.

  • What is the difference between 1-butene and 2-butene?

    Both have formula C4H8 but differ in the position of the double bond, altering their structure and shape.

  • How does branching affect carbon skeletons?

    Branching creates different isomers with the same formula but different shapes and properties, like butane vs. isobutane.

  • What is the role of buffers in biological systems?

    Buffers minimize pH changes by accepting excess H+ or donating H+ when depleted, maintaining stable conditions.