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101 Cards in this Set
- Front
- Back
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What is a monomer
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is a polymer
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If large molecules are cross-linked together what will happen
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they will form even larger molecules with different physical properties
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What causes the polymer to have a lower viscosity than the starting substance
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there is an increase in the viscosity
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What did cross linking the large molecules have an effect on
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on the increasing thickness and elasticity of the substance
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What chemical was used to to interconnect the large glue molecules
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borax
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What is viscosity dependent on
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the size of the molecule and on its "stickiness" or attraction to other molecules
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An ionic compound is
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Metal + Nonmetal
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A molecular compound is
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Nonmetal + Nonmetal
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The empirical formula is
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the lowest ration of positive to negative ions
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Bonds are formed from pairs of valence electrons
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false
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Toothpaste contains NaF. What is the name of this formula
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sodium fluoride
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For ionic compound formulas, how do you know how many of the positive ions to use and how many of the negative ions to use
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you have to make sure that the formulas balance each other out
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VSEPR theory determines the structure of molecular compounds from the number of electron groups. An electron group is
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-the electrons in a lone pair
-the electrons in a single bond -the electrons in a double bond -the electrons in a triple bond |
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A molecule with 2 electron groups around the central atom has what kind of geometry
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linear
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Iron oxides and chromium oxides are strongly colored compounds
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true
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Is PH3 a pyramid shape
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true
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(NH4)HCO3 can be used as a leavening agent for backing products
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true
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What does an (s) appearing after a formula mean
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salt
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What are the physical observations that can be used to show that there has been a chemical change
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-evolution of gas
-formation of a precipitate -formation of a product that has a different color than the reactants -formation of different oder -evolution or absorption of heat |
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During a physical change what remains the same
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the formula for the substance
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What is a physical change
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when the physical formula is the same but the physical state has changed (ex: ice melting into water)
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Sodium bicarbonate and acetic acid react to form a precipitate
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false
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What kind of compound is salt
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Metal + Nonmetal (ionic compound)
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What is a neutralization reaction
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the reaction of an acid with a base
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Magnesium sulfate reacts with sodium carbonate to produce a red color
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false
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Calcium oxide dissolved in a water solution reacts with ammonium nitrate to produce ammonia gas
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true
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Iron (III) chloride reacts with potassium thiocyanate to form carbon dioxide gas
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false
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If a solution gets cold during a reaction it is called
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endothermic
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The requirement of an electrical energy to change a product is an example of
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a chemical change
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An insoluble solid formed as the result of a reaction is called a
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formation of a precipitate
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Compared to liquids gases have a low viscosity
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true
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Compared to liquids gases have a low density
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true
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Compared to liquids gases have a low compressibility
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false
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Compared to liquids gases have a low expandability
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false
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What is air mainly composed of
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nitrogen
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Carbon dioxide is
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-denser than air
-a source of carbon for living things -contributes to the green house effect |
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Oxygen is
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-denser than air
-important for some energy producing reactions including combustion |
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Carbon dioxide was generated from the decomposition of potassium cholride
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false
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Oxygen was generated from the decomposition of carbonic acid
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false
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Low viscosity
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gases have a low resistance to flow and therefore flow more easily than liquids
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Low density
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the density of a gas is relatively low compared to the density of liquids and solids
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High compressibility
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gases can be compressed significantly with a decrease in volume
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High expandability
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raising the temperature of a gas at a constant pressure will cause the volume of the gas to increase (expand); lowering the temperature will cause the volume to decrease (contract)
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When carbon dioxide gas is "poured" onto a candle flame what happens
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the flame should be extinguished
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When a glowing stick in immersed in oxygen what happens
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the stick should burst into flames
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Hot gases produce in the combustion tube rise the tube because they are less dense than the colder gases in the surrounding air
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true
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Some fire extinguishers work by producing a smothering "blanket" of a dense gas. Which gas would you predict to be the one used
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carbon dioxide
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Electrolytes are compounds that conduct an electrical current in what
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an aqueous solution
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Cations
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positively charged ions
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Non-electrolytes
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substances that dissolve in water but whose solutions do not conduct electrical currents
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Strong electrolytes
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good conductors of electricity because they are completely dissociated into ions
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Weak electrolytes
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are only partially dissociated into ions and as a result are poor conductors of electrical currents
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Strong electrolytes include
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sodium chloride (NaCl)
hydrochloric acid (HCl) sodium hydroxide (NaOH) potassium hydroxide (KOH) potassium chloride (KCL) sulfuric acid (H2SO4) |
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Weak electrolytes include
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acetic acid (CH3COOH)
carbonic acid (H2CO3) and ammonium hydroxide (NH4OH) |
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Non-electrolytes include
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sugar
ethyl alcohol (C3H5OH) acetone acetaldehyde |
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Using the conductivity apparatus the light bulb glowed brightly when testing a strong electrolyte
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true
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The amount of voltage observed with an electrolyte is
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proportional to the amount of dissolved ion
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A KOH solution exhibiting 250mV has a lower concentration than a KOH solution exhibiting 98 mV
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true
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What are you doing when you are making coffee in a coffeepot
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you are doing an extraction
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Extraction
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a method for removing one or more substances from a sample or mixture
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Recrystallization
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a method which chemists uses to purify solid that is much more soluble in hot solvent than in cold
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Boric acid crystals were collected in the filter in each of the two filtering steps
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true
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The two filtering steps removed both insoluble and soluble impurities
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true
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If you have a very careful technique you can recover all the boric acid you started with
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true
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Minor insoluble in a recrystallization because
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their low concentration will not allow them to form crystals
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Anthrocyanins
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the colored compounds in purple cabbage, grapes, strawberries, and cranberries
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If crystals appear too early in your experiment you can correct this by either adding a little solvent or
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by adding heat
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Is a popcorn kernel mainly made up of starch or water
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starch
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What is an acid
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a hydrogen ion (H+)
proton donator |
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What is a base
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a hydroxide ion (OH-)
proton accepter |
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A popcorn kernel pops due to
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expanding steam in its starch granules
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The average weight of the popped kernel is more than the average weight for the original kernel
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false
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Why does a "dud" fail to pop
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because it doesn't have enough internal steam
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The % water content can be found from the difference in average masses of the popped and unpopped kernels divided by the average kernel mass and converted to %
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true
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In order to to pop corn what heat do you have to reach
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100 degree Celsius
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The % mass of starch in the popcorn can be found by subtracting the % water content from 100%
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true
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Who were the chemists that worked with acids and bases
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Arrhenius
Bronsted Lowery Sorenson |
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When is a hydronium ion formed
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when an acid donates a proton to a water molecule
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A solution with pH 2 is less acidic than a solution with a pH 5
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false
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A solution with pH 8 is twice as acidic as a solution with a pH 4
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false
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What does an indicator do
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it changes colors at different pH levels
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What are the sources of a base
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hydroxide ions
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What color does litmus paper turn in basic solutions
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blue
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The most common scale for measuring hydrogen ion concentration is called
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pH
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Phenolphthalein, litmus, and anthrocyanins are all examples of
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indicators
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Pure neutral water ha a pH of
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7
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A substance that resists change in pH when either base or acid is added is called a
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buffer
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Vinegar has a pH that is
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acidic
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Ammonia has a pH that is
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basic
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Borax has a pH that is
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basic
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Cream of tartar has a pH that is
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acidic
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Backing soda has a ph that is
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basic
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The "hardness" of water is generally due to which dissolved metal ions
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calcium
magnesium iron |
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What is soap made from
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the reaction of fat with lye (NaOH)
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When hard water reacts with soap what is formed
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an insoluble soap scum
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Why does a solution of soap form suds
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because of reduced surface tension of the water
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Hard water metal ions prevent the foaming action of soap by
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precipitating the soap out of solution
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If 120 mg of CaCo3 is present in a liter of water, this would be expressed as
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120 ppm (parts per million)
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Permanent hard water can be softened by the addition of
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borax or washing soda
the use of an ion exchanger |
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If enough soap is added to hard water, eventually all the "hard" metal ions will be precipitated out of a solution and additional soap will result in a foaming action
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true
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Washing away greasy dirt with ____ water will require ______ soap than if soft water is used
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1) hard
2) more |
