Chemistry: The pH Scale and Acids & Bases
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Questions and Answers

What pH value is considered neutral?

  • 7 (correct)
  • 6
  • 14
  • 0
  • Acids have a pH greater than 7.

    False

    What happens when an acid reacts with a base?

    A neutralization reaction occurs to form water.

    A solution with a pH of 3 is considered a ______ acid.

    <p>strong</p> Signup and view all the answers

    Which of the following substances is a strong acid?

    <p>Battery acid</p> Signup and view all the answers

    Match the following acids or bases with their characteristics:

    <p>Hydrochloric acid = Strong acid found in the stomach Bleach = Strong alkali Tomato juice = Weak acid Sea water = Weak alkali</p> Signup and view all the answers

    Buffers in the body help to maintain the pH within a normal range.

    <p>True</p> Signup and view all the answers

    What ions do bases produce when they dissolve in water?

    <p>Hydroxide ions (OH–)</p> Signup and view all the answers

    What pH value indicates a neutral substance?

    <p>7</p> Signup and view all the answers

    Acids have a pH greater than 7.

    <p>False</p> Signup and view all the answers

    Name one of the four major elements that constitute about 96% of the body’s mass.

    <p>Oxygen</p> Signup and view all the answers

    Substances with a pH lower than 7 are known as __________.

    <p>acids</p> Signup and view all the answers

    Match the following elements with their corresponding properties:

    <p>Oxygen = A part of water and organic molecules Calcium = Found in bones and teeth Carbon = A component of organic compounds Nitrogen = Necessary for nucleic acids</p> Signup and view all the answers

    What happens when bicarbonate combines with excess hydrogen ions?

    <p>It forms carbonic acid.</p> Signup and view all the answers

    Alkalis produce hydroxide ions (OH–) when dissolved in water.

    <p>True</p> Signup and view all the answers

    What is the role of iodine in the body?

    <p>To make thyroid hormones</p> Signup and view all the answers

    What is active transport?

    <p>Movement of ions from low to high concentration</p> Signup and view all the answers

    Larger molecular sizes result in faster diffusion rates.

    <p>False</p> Signup and view all the answers

    What is homeostasis?

    <p>The maintenance of a stable internal environment in the body.</p> Signup and view all the answers

    The normal levels of glucose in the blood are maintained between ______ mg/100 ml.

    <p>70 – 110</p> Signup and view all the answers

    Match the following components of homeostatic regulation with their functions:

    <p>Receptor = Detects changes in the environment Control Centre = Processes information and decides on action Effector = Carries out the response to restore balance</p> Signup and view all the answers

    Which of the following factors does NOT influence diffusion rates?

    <p>Age of the organism</p> Signup and view all the answers

    Positive feedback mechanisms are primarily responsible for maintaining homeostasis.

    <p>False</p> Signup and view all the answers

    Give an example of negative feedback in human physiology.

    <p>Regulation of body temperature by sweating or shivering.</p> Signup and view all the answers

    Study Notes

    pH Scale

    • Measures hydrogen ion (H+) concentration, indicating acidity or alkalinity.
    • Ranges from 0 (strongest acid) to 14 (strongest base), with 7 being neutral.
    • Acids have a pH lower than 7, with lower numbers indicating stronger acids.
    • Bases have a pH greater than 7, with higher numbers indicating stronger bases.
    • Neutral solutions have a pH of 7.

    Acids

    • Turn blue litmus paper red.
    • Turn universal indicator paper red (strong) or orange/yellow (weak).
    • Strong acids are corrosive, examples include battery acid and hydrochloric acid.
    • Weak acids are irritants, examples include tomato juice and black coffee.
    • Produce hydrogen ions (H+) when dissolved in water.

    Bases

    • React with acids to neutralize them.
    • Bases dissolved in water are called alkalis.
    • Turn red litmus paper blue.
    • Turn universal indicator paper dark blue/purple (strong) or blue-green (weak).
    • Produce hydroxide ions (OH-) when dissolved in water.

    Acid-Base Balance in the Human Body

    • Cellular processes function optimally within a pH range of 6 to 8.
    • Changes in pH can denature proteins, affect enzyme activity, alter hormone action, and disrupt cell/tissue function.
    • The body has a buffer system to maintain acid-base balance.
    • Common buffers include bicarbonate (HCO3-) and carbonic acid (H2CO3).

    Homeostasis

    • The body's ability to maintain a stable internal environment despite external changes.
    • Achieved through regulatory processes that detect imbalances and restore balance.
    • Necessary for survival as extended imbalances lead to disease and death.
    • Examples include blood glucose regulation through insulin and glucagon.

    Components of a Homeostatic Mechanism

    • Receptor: Detects changes in the internal environment.
    • Control centre: Processes information from the receptor and initiates a response.
    • Effector: Carries out the response to restore balance.

    Feedback Mechanisms in Homeostasis

    • Negative feedback: Reduces the effect of a stimulus, restoring balance.
    • Positive feedback: Amplifies the effect of a stimulus, leading to a specific outcome.

    Elements in the Body

    • 92 elements exist in nature, with hydrogen to uranium.
    • Each element has a chemical symbol, usually 1 or 2 letters.
    • Four major elements (oxygen, carbon, hydrogen, nitrogen) make up 96% of body mass.
    • Eight lesser elements (calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, iron) contribute 3.6% of body mass.
    • Trace elements are present in small amounts but have important functions (e.g., iodine for thyroid hormone production).

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    Description

    Explore the concepts of the pH scale, acids, and bases in this quiz. Understand how pH levels indicate the acidity or alkalinity of substances. Test your knowledge on how acids and bases interact, their properties, and their importance in the human body.

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