chemical reaction and bioaccumalation

Carbon Dioxide and Gas Detection

  • Carbon Dioxide Test

    • When carbon dioxide is bubbled through lime water, the solution turns milky/cloudy.

  • Test for Hydrogen Gas

    • When hydrogen gas is present, it burns with a pop sound when bringing a lit splint close to it.

  • Test for Oxygen Gas

    • Oxygen gas can be identified because it will cause a glowing splint to burst into flames.

Experimental Context

  • Experiment

    • The diagram shows an experiment where zinc metal reacts with sulfuric acid.
      a. Name of the gas produced: Hydrogen gas
      b. Testing method: Lit splint pop test
      c. Products formed: Hydrogen gas and zinc sulfate.

    • Reaction equation:

      ext{zinc} + ext{sulfuric acid}
      ightarrow ext{zinc sulfate} + ext{hydrogen gas}

Testing for Gases Produced by Chemical Reactions

  • Common Gases from Reactions:

    • Oxygen

    • Hydrogen

    • Carbon Dioxide

  • Chemical Tests for Gas Identification:

    • Test for Oxygen:

    • It relights a glowing splint.

    • Test for Hydrogen:

    • Produces a pop sound when a lit splint is approached.

    • Test for Carbon Dioxide:

    • It turns lime water milky/turbid, indicating the presence of CO2.

General Reactions and Chemical Properties

Reaction with Water

  • Certain metals react violently with water, while others do not.

  • Potassium and Sodium:

    • They are very soft and can be cut with a knife.

    • They must be stored under oil to prevent reaction with water vapor in the air.

    • Reaction Info:

    • When potassium or sodium is placed in water, hydrogen gas is released.

    • The reaction generates heat, igniting the produced hydrogen.

  • General Reaction Equation:

    ext{Metal} + ext{Water}
    ightarrow ext{Metal Hydroxide} + ext{Hydrogen gas}

    • Example: Sodium + Water

      ext{sodium} + ext{water}
      ightarrow ext{sodium hydroxide} + ext{hydrogen gas}

Reaction with Acids

  • General Equation for Reaction with Acids:

    ext{Metal} + ext{Acid}
    ightarrow ext{Salt} + ext{Hydrogen gas}

  • Example with Magnesium and Hydrochloric Acid:

    • Reaction gives off hydrogen gas and produces magnesium chloride.

    • Reaction details:

      ext{magnesium} + ext{hydrochloric acid}
      ightarrow ext{magnesium chloride} + ext{hydrogen gas}

Collection of Gas in Laboratory Settings

  • Apparatus for Collecting Gas:

    • Equipment includes:

    • Delivery tube

    • Thistle funnel

    • Measuring cylinder

    • Conical flask containing acid and metal

    • Bee-hive shelf setup in water

Signs of Chemical Reactions

  • Indicators of Chemical Reaction:

    • Bubbles of gas produced

    • Color change

    • Change in temperature (increase or decrease)

    • Formation of a precipitate (solid formed from liquid reactants)

Types of Simple Chemical Reactions

  1. Burning/Combustion:

    • A substance reacts with oxygen.

    • Example equation:

      ext{Metal} + ext{Oxygen}
      ightarrow ext{Metal Oxide}

    • Example with Carbon:

      ext{carbon} + ext{oxygen}
      ightarrow ext{carbon dioxide}

    • Example with Magnesium:

      ext{magnesium} + ext{oxygen}
      ightarrow ext{magnesium oxide}

Chemical Changes vs Physical Changes

  • Chemical Changes:

    • New substances are formed (e.g., iron + sulfur → iron sulfide).

  • Physical Changes:

    • No new substances formed (e.g., liquid water freezing).

DDT and Environmental Impact

  • What is DDT?:

    • DDT is an insecticide developed in the 1940s for killing mosquitoes and harmful insects.

    • Its persistent nature means it is not decayed by decomposers and can remain in the environment for years.

    • Toxicity:

    • DDT is harmful to various species and affects bird population by causing thinner egg shells.

Bioaccumulation & Biomagnification

  • Bioaccumulation:

    • The process where contaminants like DDT accumulate in organisms over time as they feed on others containing the chemical.

  • Biomagnification:

    • Increased concentration of DDT as one moves up the food chain.

    • Longer-lived species tend to store more DDT due to extended exposure through feeding.