Water & Solutions - for Dirty Laundry: Crash Course Chemistry #7
TLDRThis video explores the unique properties of water that make it an exceptional solvent, able to dissolve a wide variety of substances. It explains concepts like polarity, ions, electrolytes, and molarity. Examples are given to demonstrate water's ability to dissolve ionic and polar covalent substances. The process of dilution is also explained, using the example of diluting a 3% hydrogen peroxide solution to bleach laundry. Equations for calculating molarity and performing dilutions are provided. Overall, the video aims to highlight why water's polarity allows it to effectively dissolve so many substances, making it essential to biological and chemical processes.
Takeaways
- 😃 Water is abundant, polar, liquid at a wide range of temperatures - making it an excellent solvent
- 💧 Water's polarity gives it many unique and useful properties like decreasing attraction between ions (dielectric)
- 🌊 Aqueous solutions contain water as the solvent and another dissolved substance as the solute
- ⛲️ Electrolytes are substances that dissociate into ions in water, allowing solutions to conduct electricity
- 🔌 Strong electrolytes fully dissociate when dissolved while weak electrolytes only partially dissociate
- 🧪 A solution's molarity measures its concentration - moles of solute per liter of solution
- 💉 To dilute solutions, add solvent to decrease molarity while keeping solute moles the same
- 😵💫 Hydrogen peroxide is a weak electrolyte but its oxygen ion oxidizes stains, bleaching clothes
- 🛀 Water's polarity allows it to dissolve polar substances like sugar, but not nonpolar ones like oil
- 🍵 Solutions like tea demonstrate water's excellent solvent properties in everyday life
Q & A
What makes water such an effective solvent?
-Water is an effective solvent due to its polarity and its abundance on Earth. Its polarity allows it to dissolve other polar substances like sugar. Also, water is liquid over a wide temperature range, allowing more materials to dissolve.
How do electrolytes carry electric charge in water?
-When ionic compounds like salts dissolve in water, they break into their component ions which can move around independently while retaining their electric charge. These dissolved ions are called electrolytes.
Who coined the terms cation, anion, and ion?
-The terms cation, anion, and ion were coined by William Whewell at the request of Michael Faraday. Whewell proposed these terms to describe the products of electrolysis that Faraday had discovered.
What is the difference between a strong and weak electrolyte?
-A strong electrolyte like a salt dissociates completely when dissolved, creating many free ions that conduct electricity very well. A weak electrolyte like acetic acid only partially dissociates, so fewer ions are present to conduct electricity.
What is the difference between molarity and molality?
-Molarity measures the moles of solute per liter of solution. Molality measures the moles of solute per kilogram of solvent. So molarity depends on volume while molality depends on mass.
How can you calculate how to dilute a solution?
-You can use the dilution equation: M1V1 = M2V2. M1 and V1 are the original molarity and volume. M2 is the desired final molarity and V2 is the final volume after dilution.
How does hydrogen peroxide whiten laundry?
-When hydrogen peroxide dissociates, it creates reactive oxygen ions that can destroy the double bonds in stains, bleaching them colorless. However, too much peroxide could damage clothes.
Who determined that electrolyte concentration affects conductivity?
-Swedish physicist Svante Arrhenius discovered in the 1880s that the electrical conductivity of a solution depends on and can be used to determine the concentration of dissociated ions (electrolytes) present.
Why can pure water not conduct electricity?
-Pure water does not contain any ions to carry electric current. But when ionic compounds dissolve into their component ions, those electrolytes allow electric current to flow.
What properties of water contribute to its usefulness in biological systems?
-Water supports life due to properties like: high polarity that dissolves polar biomolecules, liquid state permitting chemical reactions, and dielectric nature that keeps critical biomolecules like proteins structurally intact.
Outlines
😃 Water is essential for life and chemistry
This paragraph introduces how vital water is for life on Earth. It makes up most of our bodies, enables chemical reactions, and dissolves substances well due to its polarity. Solutions, solvents, aqueous environments, and everyday uses of water chemistry are also discussed.
🔬 Measuring electrolyte concentration
This paragraph covers electrolytes in solutions and how they conduct electricity based on their concentration. The history of terms like anion, cation, and ion are shared. Svante Arrhenius linked conductivity and ion concentration, revolutionizing the field despite originally getting mediocre grades.
💧 Diluting hydrogen peroxide solution
The last paragraph starts by calling out confusing percentage notations used on chemical bottles. Then the math is shown to dilute hydrogen peroxide for laundry, including molarity, moles, and the dilution equation. The goal is a 0.1 M solution to optimize stain removal.
Mindmap
Keywords
💡water
💡polarity
💡solute
💡solution
💡solvent
💡electrolytes
💡ions
💡molarity
💡oxidation
💡dilution
Highlights
Water is the key to nearly everything, including body chemistry, food chemistry, and laundry chemistry.
Water is an extremely effective solvent due to its polarity, especially for dissolving other polar substances like sugar.
Aqueous solutions contain water as the solvent and another dissolved substance as the solute.
Water does not dissolve nonpolar substances like oil due to the lack of polarity.
Dissolving ionic compounds like salt in water separates the ions, creating electrolytes that can carry electric charge.
The higher the concentration of electrolytes in a solution, the higher its electrical conductivity.
Strong electrolytes like salts and strong acids fully dissociate in water, while weak electrolytes only partially dissociate.
The molarity of a solution refers to moles of solute per liter of solution.
Diluting a solution involves adding more solvent while keeping the moles of solute the same.
An important rule for understanding dilutions is: the moles of solute before dilution equals the moles after.
The dilution equation allows calculating new molarity and volume when diluting solutions.
Hydrogen peroxide is used to bleach laundry via oxidation, destroying the double bonds that give stains their color.
Too much peroxide can actually dissolve clothes, so diluting it to the right concentration is important.
Weight percentage solutions with different units of measurement are not good chemistry terminology.
Water's polarity gives tea and other aqueous solutions their delightful properties.
Transcripts
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