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75 Cards in this Set
- Front
- Back
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Define the term solute |
A substance that is dissolved in a solvent to form a solution |
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Define the term solvent |
The medium in which a solute is dissolved; often the liquid component of a solution |
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Define the term solution |
A homogeneous mixture of substances composed of at least one solute and one solvent |
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Define the term solubility |
A property of a solute; the concentration of a saturated solution of a solute in a solvent at a specific temperature and pressure |
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Define the term aqueous solution |
A solute dissolved in water |
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Define the term miscible |
Liquids that mix in all properties and have no maximum concentration |
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Define the term immiscible |
Two liquids that form separate layers instead of dissolving |
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Define the term saturated solution |
A solution containing the maximum quantity of a solute at specific temperature and pressure conditions |
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Define the term unsaturated solution |
A solution in which the solvent is able to absorb more solute at a particular temperature |
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Define the term super-saturated solution |
A state of a solution that contains more of the dissolved material than could be dissolved by the solvent at a particular temperature |
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What is the purpose of water treatment plants? |
- To produce safe, pleasant drinking water that is free of disease causing organisms and toxic substances. - The water should not have a disagreeable taste, odor, or appearance. - All levels of government are responsible in ensuring that Canada's drinking water is safe (Federal, Provincial, Municipal). |
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What are the types of water contaminants? |
- Biological (viruses, bacteria, and algae) - Chemical (all dissolved substances) - Physical (suspended particles that make the water appear dirty) |
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What are the steps to the water treatment process? |
1) Collection 2) Coagulation, Flocculation & Sedimentation 3) Filtration 4) Disinfection 5) Fluoridation |
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Describe the collection step of the water treatment process of water treatment. |
- Water passes through the filtration screen - Prevents items (fish, sticks, aquatic plants) from entering the treatment facility and damaging equipment |
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Describe the coagulation, flocculation and sedimentation process of water treatment. |
- Aluminum sulfate (Alum) is a coagulant added to the water - Suspended particles are removed by the coagulant causing the particles to stick - Slow mixing process helps particles to stick together making them bigger and heavier to settle to the bottom of the tank |
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Describe the filtration process of the water treatment |
- Remaining particles and chlorine-resistant bacteria are removed - The water travels through layers of granual activated carbon (for taste and odor control), sand & gravel. - Water moves down the layers by gravity |
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Describe the disinfection process of the water treatment |
- Chlorine is added to destroy harmful bacteria such as E.coli and parasites such as Giardia |
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Describe the fluoridation process of the water treatment |
-Fluoride is added to the finished water to prevent cavities in our teeth - The finished water is then stored in a reservoir and pumped into our communities through the water distribution system - Only optional step |
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What are some characteristics of water? |
- Oxygen has a greater electronegativity value than hydrogen, causing the atoms to share electrons unequally, creating a polar molecule - Water is a very good solvent because it is a polar molecule - The hydrogen is slightly positive - The oxygen is slightly negative |
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What types of compounds are soluble in water? |
Ionic compounds - When ionic compounds dissolve in water, they form aqueous solutions of dissociated ions - The ions are separated and surrounded by polar water molecules |
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Draw a diagram of how NaCl dissolves in water |
- Positive hydrogen end of the water molecules are attracted to the negative ion (Cl-) - Negative oxygen ends are attracted to the positive ion (Na+) |
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Explain hydrogen bonds in water |
- Opposite charges attracting allow for their formation - Strong attraction between the oxygen atom of one water molecule and hydrogen atoms of adjacent water molecules (example of hydrogen bond) |
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Why are water molecules called polar? |
It has opposite charges on different parts of the same molecule |
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Describe a polar substance. |
- Has charges that can interact with charges in water - Said to be hydrophilic (water-loving) |
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Describe a non-polar substance. |
- Lack any charges and will not be able to interact with water - Said to be hydrophobic (water hating) |
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How do you predict the solubility in water? |
Polar solvent: If the solute is polar or ionic, it's usually soluble. If the solute is non polar, it's usually insoluble. Non-polar solvent: If the solute is polar or ionic, it's usually insoluble. If the solute is non polar, it's usually soluble. (Use solubility guidelines) |
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What are some of the beneficial ions found in water? |
- Iron and magnesium ions are found in blood and tissue - Low levels of iron are beneficial - Calcium is good for bones and teeth |
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What are some negative ions found in water? |
- Sulfur ions give water a bad odor - High concentrations of iron give water a bad taste - Heavy metal ions such as mercury, lead, calcium and arsenic are harmful to human health |
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What are the factors which affect the rate of solubility? |
1) Temperature: For most solutions, the rate of dissolving increases as the temperature increases. This is because the molecules speed up so they collide more often. 2) Agitation: Stir or shake a solution to increase the dissolving process. This allows fresh solvent to come in contact with it. 3) Surface Area: Surface area of particles will affect the rate of dissolving. If the particles are small, they will dissolve faster because their surface area is greater; allowing for more solvent to come in contact with it. |
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What are solubility curves? How are they graphed? |
- Gives information about the solute by indicating how much solute can be dissolved in the solvent at different temperatures - When graphing solubility curves, the temperature is the independent variable and is on the x-axis - The solubility is the dependent variable and is on the y-axis. - Line of best fit: smooth line; may curve |
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What are ionization equations? |
Equations where the compounds are broken up into their ions. ex. |
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What are net ionic equations? |
- With net ionic equations two compounds are combined together but only ions that react are recorded - The ions that are eliminated from the equation are called spectator ions because they are not involved in the reaction |
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How do you calculate concentration as a mass/volume % ? |
- A mass/volume percent gives the mass of solute dissolved in a volume of solution - Mass/Volume % = mass of solute (in g) / mass of solution (in mL) x 100 |
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How do you calculate concentration as a mass/mass % ? |
- Solution can be expressed as the mass of solute dissolved in the mass of solution - Mass/Mass % = mass of solute (in g)/mass of solution (in g) x 100 |
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How do you calculate concentration as a volume/volume % ? |
- This expresses the solution as the volume of solute divided by the volume of solution - Volume/Volume % = volume of solute (in mL)/volume of solution (in mL) x 100 |
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How do you calculate parts per million? |
ppm = (mass of solute/mass of solution)(10^6) |
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How do you calculate parts per billion? |
ppb = (mass of solute/mass of solution)(10^9) |
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What is molar concentration? |
- Molar concentration is the number of moles of solute than can be dissolved in 1L of solution - It is also called Molarity |
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How is molarity calculated? |
C = n/V - C is the molar concentration in mol/L - n is the number of moles (mol) - V is the volume in liters (L) |
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What are the properties of acids based on... Taste, feel/texture, electrical conductivity, pH, corrosion, indicator colors (litmus, phenolphthalein), reaction with active metals, and 3 examples. |
Taste: Sour Feel/Texture: No characteristic texture Electrical Conductivity: Conducts electricity pH: Less than 7 Corrosion: Corrodes tissue and metal Indicator colors: Red litmus, color for other Reaction with metals: Produces hydrogen gas Examples: Acetic acid, citric acid, hydrochloric acid |
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What are the properties of bases based on... Taste, feel/texture, electrical conductivity, pH, corrosion, indicator colors (litmus, phenolphthalein), reaction with active metals, and 3 examples. |
Taste: Bitter Feel/Texture: Slippery Electrical Conductivity: Conducts electricity pH: Greater than 7 Corrosion: Corrodes tissue, not metal Indicator colors: Blue litmus, pink for other Reaction with metals: Do not react Examples: Ammonia, sodium hydroxide, bleach |
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What are amphiprotic or amphoteric substances? |
- A type of substance than can act as an acid or as a base in different chemical reactions - Water is the most common amphiprotic compound |
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What did Arrhenieus propose for acids? |
- That water can dissociate many ionic compounds by separating them into their individual ions - Arrhenius suggested that acids are ionic compounds that contain hydrogen and can dissociate in water to release hydrogen ions into the solution - IN ACIDS HYDROGEN IN CONSIDERED A METAL |
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What did arrhenius define bases as? |
Ionic compounds that dissociate in water to release hydroxide ions (OH-) into solution |
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Overall what do Arrhenius's theories explain? |
- Why all acids have similar properties to each other (and, conversely, why all bases are similar): because all acids release H+ into solution (and all bases release OH-) |
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What is pH? |
- A measure of how acidic or basic an aqueous solution is - The pH scale is used to measure how acidic or basic a solution is The pH scale ranges from 0-14: Acids have a pH from 0-6.9 Bases have a pH range from 7.1 to 14 Neutral solutions have a pH of 7.0 |
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How is pH calculated? |
- pH means the power of hydrogen. - It can be calculated with the equation pH = -log[H+] - [H+] represents the concentration of hydrogen ions - pH has no units |
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How is the [H+] determined from pH? |
When the pH of a solution a known, [H+] = 10^-pH |
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What happens when acids and bases are added to water? |
- Both acids and bases start as ionic compounds - Acids produce H+ ions, bases produce OH- ions - If a compound dissociates completely, it's considered a strong acid or base - If more than 50% of the compound remains undissolved, it is considered a weak acid or base |
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What are the examples of strong acids? |
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What are the examples of strong bases? |
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What are the examples of weak acids? |
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What are the examples of weak bases? |
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What is a neutralization reaction? |
- Reaction between acid and base - it is a double displacement reaction that involves an acid reacting with a base to form a salt and water |
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Define titration |
A common lab procedure in which the concentration of one solution is determined by its reaction with a solution of a known concentration. The solution of known concentration is called the titrant. |
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What is a burette? |
A special piece of glassware used in a titration experiment to measure the volume of titrant that is added to the sample with unknown concentrations. |
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What is the endpoint? |
The point in a titration when the indicator changes colour. |
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What are commonly used indicators? |
- Bromthymol blue is yellow in acids, green at the endpoint, and blue in bases. - Methyl orange is red in acids, orange at the endpoint, and yellow in bases - Phenolphthalein is colourless in acids, light pink at the endpoint, and bright pink in bases |
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What are the steps for performing a titration? |
1) A known volume of a sample is put into an Erlenmeyer flash using a pipette. This is the solution with the unknown concentration. 2) 1-2 drops of indicator is added to the Erlenmeyer flask. 3) The titrant is put into the burette 4) Record the initial titrant volume in the burette, Slowly add the titrant to the flash until the indicator changes colour. Record the final volume in the burette. The difference in the volume readings is the volume of titrant added to neutralize the solution in the Erlenmeyer flask. |
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What is a standard solution? |
A solution that has a known concentration |
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What is a stock solution? |
A solution that is in stock or on the shelf already prepared, usually a concentrated solution |
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What is pure water? |
Deionized or distilled water |
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What is a dilution? |
The process of decreasing the concentration of a solution, usually by adding more solvent. |
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What are the two ways to prepare a standard solution? |
1) Preparing a standard solution from a solid - Using a volumetric flask 2) Preparing a standard solution by diluting |
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Describe how to prepare a standard solution from a solid. |
- Precision equipment required to measure the mass of solute and volume of solution - To make a solution with known concentration, dissolve a solute of known mass in a volumetric flask - Use the equations.. C=n/V and m=nM to determine the mass of solute you need to prepare a particular volume of solution of known concentration. |
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What are the steps to make a standard solution? |
1) Use an electronic balance to measure the desired mass of solute 2) Transfer all of the solute to the volumetric flask 3) Add the solvent to the volumetric flask until it is about half full. The swirl the flask to dissolve the solid. 4) Fill the flask by adding water using a washbottle, until the bottom of the meniscus touches the etched line on the flask. 5) Stopper the flask and mix the contents by inverting the flask |
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Describe how to prepare a standard solution by diluting? |
- Possible to make a more dilute solution using a standard solution - To calculate a dilution the following formula is used : C1V1=C2V2 (C1 is the initial concentration, C2 is the final concentration, V1 is the initial volume, V2 is the final volume) |
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What are the steps to make a diluted solution from a stock solution? |
1) Determine the amount of standard solution required and use the pipet to measure it out. Put this volume into a volumetric flask. 2) Add the rest of the solvent to the flash until the meniscus appears to touch the line found around the neck of the flask 3) Mix the contents by repeatedly inverting the flask 4) Before and after the dilution, the number molecules and moles do not change. |
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What is the purpose of adding chlorine to water? |
- To disinfect drinking water by reducing or eliminating microorganisms such as bacteria and viruses in water supplies. It has greatly reduced the risk of water borne diseases. |
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What are the pros of chlorination? Cons? |
Pros: Free of microorganisms causing serious and life-threatening diseases, easy to apply, microorganisms cannot recontaminate water after leaving plant because a small amount remains in the water Cons: Produces THM's such as chloroform when chlorine reacts with organic matter. Exposure to THM's make increase risk of cancer, or affect pregnancy (miscarriage). |
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What is the established safe amount of THM's that Health Canada has established for drinking water? |
0.1 milligrams per litre |
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What are alternative to chlorination? What are their pros and cons? |
Ozonation...Pros: Does not produce THM's. Effective disinfectant. Cons: Breaks down quickly, cannot maintain disinfection in distribution. Renovating to use ozone can be expensive. Chloramines...Pros: Very effective in distribution system. Cons: Weaker disinfectant than chlorine Chlorine Dioxide...Pros: Can be used in treatment plant. Cons: Not effective in distribution system. |
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What is the purpose of adding fluoride in drinking water? |
To prevent tooth decay |
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What are the pros and cons of adding fluoride in drinking water? |
Pros: Prevents dental cavities, protects tooth enamel against acids causing tooth decay, reduces cavities in children's teeth Cons: Can cause risk of developing dental fluorosis in children from swallowing tooth paste, high levels of fluorides consumed for a long period of time may lead to skeletal fluorosis. |
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What is the optimal concentration of fluoride in drinking water to promote dental health? What is the acceptable concentration of fluoride in drinking water made by Health Canada? |
Optimal concentration: 0.7mg/L Acceptable concentration 1.5mg/L |
