Chemistry of Water Quiz
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Questions and Answers

What percent of Earth's surface is covered by water?

75%

What is the chemical formula for water?

H₂O

What is the name of the solid state of water?

Ice

At what temperature does water freeze?

<p>0 degrees Celsius</p> Signup and view all the answers

At what temperature does water boil?

<p>100 degrees Celsius</p> Signup and view all the answers

What type of molecule is water?

<p>Polar covalent (B)</p> Signup and view all the answers

What is the approximate bond angle of a water molecule?

<p>104.5 degrees</p> Signup and view all the answers

What type of bond is formed between water molecules?

<p>Hydrogen bond</p> Signup and view all the answers

What is the name for the attraction between water molecules?

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

What is the name for the attraction between water molecules and other substances?

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

What property of water allows it to resist external forces?

<p>Surface tension</p> Signup and view all the answers

What are reasons the water strider can walk on water?

<p>Their weight is not enough to penetrate the surface due to the surface tension.</p> Signup and view all the answers

Why does a paper clip made of steel float on water?

<p>The high surface tension of water.</p> Signup and view all the answers

What is the reason that droplets of water are spherical?

<p>The cohesive forces of the surface layer.</p> Signup and view all the answers

Why are some tent materials rainproof?

<p>The surface tension of water bridges the pores of the material, preventing rain from dripping through.</p> Signup and view all the answers

What is the effect of disinfectants on surface tension?

<p>Disinfectants reduce surface tension, which allows them to spread out over surfaces and disrupt bacteria.</p> Signup and view all the answers

Explain how soaps or detergents help clean clothes?

<p>They reduce the surface tension of water, allowing water to penetrate the fibers and loosen dirt.</p> Signup and view all the answers

Why is cold water preferred for washing?

<p>Because it has lower surface tension and better wetting ability.</p> Signup and view all the answers

What is the reason that bubbles are round?

<p>The surface tension of water provides the necessary wall tension.</p> Signup and view all the answers

What type of action allows water to climb capillary tubes?

<p>Capillary action</p> Signup and view all the answers

Explain why the water level in a capillary tube is higher at the edges than in the middle.

<p>Water molecules are more strongly attracted to glass due to its polarity.</p> Signup and view all the answers

How does capillary action contribute to nutrient transport in plants?

<p>It aids in the movement of water and nutrients from the roots to the upper parts of the plant.</p> Signup and view all the answers

What gives water its ability to moderate temperature?

<p>Its high specific heat and high heat of vaporization.</p> Signup and view all the answers

What is meant by the term “high specific heat”?

<p>It refers to the amount of energy to change the temperature of 1 gram of a substance by 1 degree Celsius.</p> Signup and view all the answers

How do hydrogen bonds contribute to water's high specific heat?

<p>They absorb and release heat, minimizing temperature changes.</p> Signup and view all the answers

Why is water's high heat of vaporization important?

<p>It helps moderate temperatures, keeping the environment relatively stable.</p> Signup and view all the answers

How does the high heat of vaporization contribute to body temperature homeostasis?

<p>It helps maintain a stable body temperature by removing excess heat.</p> Signup and view all the answers

Why does water have unusually high boiling and freezing points?

<p>Its energy requirement to break hydrogen bonds.</p> Signup and view all the answers

What is the effect of water's high boiling and freezing points on ecosystems?

<p>They prevent drastic environmental changes, allowing life to thrive.</p> Signup and view all the answers

Ice is more dense than liquid water.

<p>False (B)</p> Signup and view all the answers

Why does ice float?

<p>Its lower density compared to liquid water.</p> Signup and view all the answers

Why do only the top parts of lakes freeze in winter?

<p>The ice insulates the water below.</p> Signup and view all the answers

Why is water considered a universal solvent?

<p>Its polarity allows it to dissolve many substances.</p> Signup and view all the answers

How do hydrogen bonds contribute to the dissolving of compounds in water?

<p>They form hydration shells around ions, maintaining particle separation.</p> Signup and view all the answers

Explain the reactivity of alkali metals with water.

<p>They react violently and explosively, displacing hydrogen gas and forming hydroxide ions.</p> Signup and view all the answers

What type of solution is formed when alkali metals react with water?

<p>A basic or alkaline solution.</p> Signup and view all the answers

How do alkaline earth metals react with water?

<p>They also form hydroxides and hydrogen gas, but the reactions are generally less violent than with alkali metals.</p> Signup and view all the answers

Which alkaline earth metal does not react with water?

<p>Beryllium (Be)</p> Signup and view all the answers

How do the reactions of alkali metal oxides and alkaline earth metal oxides with water differ?

<p>Both produce hydroxides, but alkaline earth metals react with water to form hydroxide salts whereas the alkali metal oxides react with water to produce metal hydroxides, which are more soluble than the salts.</p> Signup and view all the answers

What is the common name for calcium oxide?

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

How do alkaline earth metal hydrides react with water?

<p>They produce metal hydroxides and hydrogen gas.</p> Signup and view all the answers

Why are most Group 13 elements not very reactive with water?

<p>The formation of a protective oxide layer on their surface prevents further reaction.</p> Signup and view all the answers

What is the common reaction of Group 14 elements with water?

<p>They generally do not react with water.</p> Signup and view all the answers

How is tin used in preventing corrosion of iron cans?

<p>It is sprayed as a protective layer on the cans.</p> Signup and view all the answers

Group 15 elements react readily with water.

<p>False (B)</p> Signup and view all the answers

What is the common result of the reaction between Group 1 and Group 2 oxides with water?

<p>They form metal hydroxides.</p> Signup and view all the answers

What type of compounds are formed when nonmetal oxides react with water?

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

What is the common effect of halogens reacting with water?

<p>They form halides and hypohalides.</p> Signup and view all the answers

What is the general reaction of halogens with water?

<p>They react to form a halides, hypohalides, and sometimes oxygen gas</p> Signup and view all the answers

Briefly describe the properties of noble gases.

<p>They are odorless, colorless, nonflammable, and have low reactivity.</p> Signup and view all the answers

Why do noble gases not react with water?

<p>They have little tendency to gain or lose electrons.</p> Signup and view all the answers

Describe the composition of water.

<p>Water is composed of two hydrogen atoms bonded to one oxygen atom.</p> Signup and view all the answers

Define cohesion and explain its action on water molecules.

<p>Cohesion is the attraction between like molecules, in this case, between water molecules. Cohesion causes water molecules to stick together tightly, which explains why water forms droplets.</p> Signup and view all the answers

Define adhesion and explain how it affects the behavior of water molecules.

<p>Adhesion is the attraction between unlike molecules. In the case of water, when water molecules are close to other surfaces, such as glass, the water molecules are attracted to the surface. Adhesion helps to explain why water will climb up the inside of a glass tube.</p> Signup and view all the answers

Why is water a polar molecule?

<p>Water is a polar molecule because the oxygen atom is more electronegative than the hydrogen atoms, which means that the electrons in the molecule are not shared evenly. This uneven sharing of electrons results in the oxygen atom having a partial negative charge and the hydrogen atoms having a partial positive charge.</p> Signup and view all the answers

List the properties of water.

<p>Some of the properties of water include surface tension, cohesion, adhesion, high specific heat, high heat of vaporization, universal solvent, and less dense in solid state.</p> Signup and view all the answers

What is surface tension? Provide 3 examples of water's surface tension.

<p>Surface tension is the force that causes the surface of a liquid to behave as if it were a stretched elastic membrane. The force of surface tension results from the attraction between the molecules of the liquid. Some examples include water striders walking on water, paper clips floating on water, and droplets of water forming spherical shapes.</p> Signup and view all the answers

What is the importance of water's capillary action?

<p>Capillary action plays a crucial role in nutrient transport in plants and it is a key factor in the movement of water through many natural systems, such as the soil and the human body.</p> Signup and view all the answers

List three important effects of water's high specific heat.

<p>High specific heat makes water an effective temperature regulator, protecting organisms from extreme temperature changes. High specific heat helps to moderate the climate, making the Earth more hospitable for life. High specific heat plays an important role in many industrial processes, such as in cooling systems and power plants.</p> Signup and view all the answers

Why does ice float? Why does only the top part of lakes freeze in the winter?

<p>Ice floats because it is less dense than liquid water, which is due to the arrangement of water molecules in ice, forming a crystalline structure with more empty space. The top part of lakes only freeze because the ice acts as an insulating layer, preventing the water below from freezing.</p> Signup and view all the answers

Flashcards

Water's Composition

Water is a compound composed of two hydrogen atoms and one oxygen atom, with a chemical formula of H2O.

Cohesion

Cohesion refers to the attraction between molecules of the same substance. Water molecules exhibit strong cohesion due to hydrogen bonding.

Adhesion

Adhesion is the attraction between molecules of different substances. Water molecules adhere to other polar surfaces, like glass.

Water: A Polar Molecule

Water is a polar molecule because the oxygen atom has a stronger pull on electrons than the hydrogen atoms, creating partial negative and positive charges.

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Water's Properties

Water has several unique properties: high specific heat, high heat of vaporization, surface tension, capillary action, and its ability to be a universal solvent.

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Surface Tension: What is it?

Surface tension is the inward force that causes a liquid's surface to behave like an elastic membrane. Water has high surface tension due to strong hydrogen bonds.

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Surface Tension: Insect on Water

Small insects, like water striders, can walk on water because their weight is less than the surface tension of water.

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Surface Tension: Floating Paper Clip

A paper clip, even though denser than water, can float due to surface tension. The surface tension holds the paper clip up.

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Surface Tension: Liquid Droplets

Water droplets form a spherical shape because of surface tension. The molecules at the surface try to minimize their surface area.

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Capillary Action's Importance

Capillary action helps plants transport water and nutrients from roots to leaves. Adhesion and cohesion create a force that pulls water upwards.

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Water's High Specific Heat

Water has a high specific heat, meaning it requires a lot of energy to raise its temperature. This is due to strong hydrogen bonds.

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High Specific Heat: Importance for Life

Water's high specific heat helps maintain stable temperatures in living organisms and the environment, preventing drastic temperature fluctuations.

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High Specific Heat: Industrial Use

Water's high specific heat makes it a great coolant in industrial processes, helping to dissipate heat and prevent overheating.

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Ice Floats?

Ice floats because it is less dense than liquid water. This is due to the open, crystal-like structure formed by hydrogen bonds in ice.

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Lakes Freeze From the Top Down

Lakes freeze from the top down because ice is less dense than water. The ice insulates the water underneath, allowing aquatic life to survive.

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Water's Phases: Liquid

Liquid water is the most common phase under standard conditions. Hydrogen bonds constantly form and break, allowing water molecules to move freely.

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Water's Phases: Gas (Water Vapor)

Water vapor is the gaseous phase of water. It forms when heat breaks all hydrogen bonds, allowing water molecules to escape into the air.

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Water as a Universal Solvent

Water is a universal solvent due to its polarity. The positive and negative ends of water molecules can attract and dissolve many substances.

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Salts Dissolving in Water

Salts dissolve in water because the charged ions are attracted to the oppositely charged ends of water molecules. Hydration shells form around the ions.

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Monoxides Reacting with Water

Monoxides, like carbon monoxide (CO), react with water to form acids. For example, CO reacts with water to form carbonic acid (H2CO3).

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Peroxides Reacting with Water

Peroxides, like hydrogen peroxide (H2O2), react with water to produce oxygen gas and water. This reaction often releases heat.

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Superoxides Reacting with Water

Superoxides, like potassium superoxide (KO2), react with water to produce oxygen gas, a metal hydroxide, and hydrogen peroxide.

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Alkali Metal Hydrides Reacting with Water

Alkali metal hydrides, like sodium hydride (NaH), react with water to form metal hydroxide and hydrogen gas.

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Alkali Metals Reacting with Water

Alkali metals, like sodium (Na), react violently with water to produce metal hydroxide and hydrogen gas.

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Alkaline Earth Metal Monoxides with Water

Alkaline earth metal monoxides, like calcium oxide (CaO), react with water to form a metal hydroxide.

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Alkaline Earth Metals with Water

Alkaline earth metals, like magnesium (Mg), react with water to form a metal hydroxide and hydrogen gas.

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Group 13 Elements and Water

Group 13 elements, like aluminum, generally do not react with water. Aluminum forms a protective oxide layer that prevents further reaction.

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Group 14 Elements and Water

Group 14 elements, like tin, do not react with water. This makes tin a good protective layer for metals like iron.

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Group 15 Elements and Water

Group 15 elements, like nitrogen, typically do not react with water. Nitrogen compounds like nitrates and nitrites dissolve in water but do not chemically react.

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Halogens Reacting with Water

Halogens, like chlorine and bromine, react with water to produce halides, hypohalides, and sometimes oxygen gas.

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Noble Gases and Water

Noble gases, like helium and neon, do not react with water. Their full valence electron shells make them very stable.

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Study Notes

Chemistry of Water

  • Water covers 75% of Earth's surface
  • It's the most abundant compound in living organisms
  • Found as gas, liquid, and solid
  • Exists as oceans, lakes, rivers, groundwater, ice sheets, snow, and water vapor in the atmosphere
  • Essential for life development and nourishment

Objectives

  • Identify the different composition of water
  • Explain why water is polar
  • Explain hydrogen bonding in water
  • Explain the symmetry of the water molecule
  • Differentiate cohesion and adhesion
  • State why water has high specific heat and its importance in the surroundings
  • State the importance of water's high heat of evaporation
  • State the importance of ice having lower density
  • Discuss the different phases of water
  • Discuss why water is a universal solvent
  • State the different reactivity of water to the different groups in the periodic table

Composition of Water

  • Water is a clear, odorless, and tasteless liquid
  • Chemical formula: Dihydrogen oxide (H₂O)
  • Freezes below 0 degrees Celsius
  • Boils above 100 degrees Celsius
  • Exists in solid (ice), liquid, and gaseous (water vapor/steam) states
  • Defined by the triple point: 273.16 K (0.01°C) and 611.2 Pa

Structure of Water

  • Polar covalent molecule with one oxygen atom and two hydrogen atoms
  • Oxygen attracts shared electrons more than hydrogen
  • Partial negative charge on oxygen (-δ) and partial positive charges on hydrogens (+δ)
  • Bent shape (104.5°)
  • Polar due to uneven electron sharing

Symmetry of Water Molecule

  • Exhibits symmetrical properties
  • Two mirror planes
  • One perpendicular plane
  • 2-fold rotation axis
  • Remains unperturbed when rotated 180°
  • Point group C2v

Properties of Water

  • Surface Tension: Water molecules are attracted to each other (cohesive) and to other substances (adhesive)

    • Examples: water striders walking on water, paper clips floating on water, water droplets forming spheres, tent materials being rainproof

  • Capillary Action: Water moving up narrow tubes (e.g., plant stems, tiny capillaries) due to adhesion (to tube walls) and cohesion (between water molecules)

  • High Specific Heat: Water absorbs and releases significant heat energy with minimal temperature change

    • Importance: moderates temperature, protects living organisms (e.g., regulates body temperature), industrial coolants

  • High Heat of Vaporization: Water absorbs a lot of energy to vaporize

    • Importance: moderate temperature, regulate body temperature, cooling effect

  • Lower Density of Ice: Ice is less dense than liquid water

    • Importance: prevents lakes and rivers from freezing solid, allowing life to survive

Water as a Universal Solvent

  • Water's polarity allows it to dissolve many substances (ionic and some polar molecules)
  • Forms hydration shells around dissolved ions

Reactivity of Water with Different Groups in the Periodic Table

  • Group 1 (Alkali Metals): Displace hydrogen from water, forming hydroxides, producing hydrogen gas
  • Group 2 (Alkaline Earth Metals): React with water to form hydroxides and hydrogen gas (alkali metals)
  • Group 13 (Boron Family): Not very reactive with water, except for Aluminum which forms an oxide layer that protects it
  • Group 14 (Carbon Family): Generally nonreactive with water
  • Group 15 (Nitrogen Family): Not reactive with water
  • Group 16 (Oxygen Family): Many oxides react with water to form metal hydroxides
  • Group 17 (Halogens): React with water, producing hydrogen halides (usually strong acids) and oxygen
  • Group 18 (Noble Gases): Nonreactive with water

Engaging activities

  • Describe the composition of water: Water is composed of two hydrogen atoms and one oxygen atom (H₂O)

  • Define cohesion: The attractive forces between like molecules

  • Explain cohesive action of water molecules: Water molecules are attracted to each other through hydrogen bonds, creating a strong force that enables them to stick together

  • Define adhesion and explain adhesion action of water molecules: Adhesion refers to the attraction of water molecules to unlike molecules. Water molecules are strongly attracted to polar substances like glass and other surfaces, allowing them to climb up narrow tubes against gravity through capillary action.

  • Why is water a polar molecule: Water is a polar molecule due to the unequal sharing of electrons between oxygen and hydrogen atoms.

  • Enumerate the properties of water: surface tension, cohesion, adhesion, high specific heat, high heat of vaporization, lower density of ice

  • Water surface tension examples: water striders on water, paperclips floating on water, the shape of water droplets

  • Importance of capillary action: responsible for water moving up narrow tubes, crucial for plant nutrient transport

  • Importance of water having a high specific heat: moderates temperature fluctuations in the environment and within living organisms

  • Why does ice float? Why only the top part of the lakes are frozen? Ice is less dense than liquid water because the hydrogen bonds create a more open, less compact structure. This lower density allows ice to float on water. The insulating layer of ice on top of bodies of water prevents deeper water from freezing, maintaining the environment's integrity.

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SLM11-SCI-1-Chemistry-of-Water PDF

Description

Test your knowledge about the unique properties and composition of water. This quiz covers essential concepts such as hydrogen bonding, polarity, and the importance of water in relation to living organisms. Dive in to explore why water is often referred to as the universal solvent and its various phases.

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