Module 3 - Aqueous Solutions and Reactions in Water
Let's examine a sample of fluoride being prepared in a lab. What is the molarity of this sample?
(2.3 mols NaF / 0.5 L solution) = 4.6 M
Select all of the measurements that contain 2 significant digits.
(Wrong)1700 6500 1500 New: 1700 6500 1500 8.9 x 104
Measurement She measures the volume as 44.8 mL Select which of the following are true about Kate's measurement:
- The 8 in 44.8 is the uncertain digit. - This measurement contains uncertainty.
Match each chlorine containing acid to its name. Hydrochloric acid Perchloric acid Chloric acid Chlorous acid Hypochlorous acid
HCl, HClO4, HClO3, HClO2, HClO
Using your knowledge of the Brønsted-Lowry theory of acids and bases, predict the formula of the conjugate base of the reaction below. HNO3 + OH- à * where OH- is the base
HNO3 is an acid, based on the Bronsted-Lowry theory for acids: acids are H+ ion donors. Resulting in NO3 + H2O
Using your knowledge of the Brønsted-Lowry theory of acids and bases, predict the formula of the conjugate acid of the reaction below. OH- + HPO4-2 à *where OH-1 is the base
HPO4-2 loses its H to the OH- and becomes H2O + PO4-2 based on the Bronsted-Lowry theory for acids: acids are H+ ion donors.
Mod 6 Double Replacement Double-Replacement Reactions Select the single best answer below to describe double replacement:
Two different things change places with each other.
What's common to all the reactions above? Select the best answer.
Two ionic compounds exchange parts and form two new compounds. Either water, a gas, or a precipitate is formed.
Neutralization Reactions When you think of the term neutralization, what does it bring to mind?
Two things cancel each other out.
Oil does not dissolve in water because: C) water is nonpolar. D) water is saturated. E) oil is hydrated.
oil is nonpolar
An ant walks 3.0 inches per second. How many miles per day could an ant travel if it walked without taking a break?
4.1
A mass of 0.15 ounces is equal to how many grams?
4.3
Perform the arithmetic and express your answer with correct significant figures: (5.7 - 4.21) x 3.42 = ________________
5.10
Match the following measurements to their uncertainty.
5.1125 = + -0.0001 23.4 = + -0.1 62.34 = + -0.01
A 10. Km race is how many miles?
6.2
Review III Calculate the answer to the following questions: How many significant figures are in 0.002580100?
7 114 26.2
A solution has a [H3O+] of 1 X 10-7 M. Its pH is _________ and it is __________.
7, neutral
2.00 gallons is equal to how many liters?
7.57
Select all of the measurements that contain 4 significant digits.
7600. 1001 0.9870 90870 100.0
A solution has a [H3O+] of 7.2 X 10-9 M. Its pH is _________ and it is __________.
8, basic
8.9 daL is equal to _____________mL
8.9 x 10^4
1.87 + 3.5 x 2
9
What is the pH of a solution if the [OH-] = 2 X 10-5 M? express your answer with 1 significant figure
9
Fill in the blanks to describe what units you are starting out with. The prescription calls for ? ? of ? .
? - 0.1 ? - grams ? - dilantin
The substance with a pH of 5 is ? ? acidic or ? ? basic than the substance with a pH of 2
? - 1000x ? - less ? - 1000x ? - more
Multiply all the values in the numerators and divide by the product of all denominators. Product of numerators - ? Product of denominators - ? Product of numerators / Product of denominators - ?
? - 500 ? - 30 ? - 16
As a general rule, acids have a pH ? and bases have a pH ?. Arrhenius acids in ? water. An Arrhenius base in ? water. Not all acids and bases fit this simple definition, however. Brønsted-Lowry acids are ? while Brønsted-Lowry bases, like NH3, are ?.
? - below 7 ? - above 7 ? - dissociate into H+ ions ? - dissociate into OH- ions ? - H+ ion donors ? - H+ ion acceptors
conjugate
A conjugate acid, within the Brønsted-Lowry acid-base theory, is a chemical compound formed when an acid donates a proton (H+) to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a hydrogen ion.
Quiz Which is the acid in the reaction below? HCl + H2O à H3O+ + Cl-
HCL
Does your calculated level of lead meet the action level?
I can't tell, given that the units are not in molarity
What's common to all the reactions above? Select the best answer.
In each reaction, an element reacts with a compound and takes the place of another element in that compound.
1 ppm is a thousand times more concentrated than 1 ppb (part per billion). 1 ppm is equivalent to 1 mg / L 1 ppb is equivalent to 1 ug / L * ug is a microgram, and a microgram is 10-6 grams or 0.0000001 grams.
Match the unit of concentration to the correct term: Molarity - mols/liter ppm - mg/L ppb - ug/L
Would water form a sphere of hydration around this substance?
No, because this molecule is nonpolar.
Single-Replacement Reactions Select the single best answer below to describe single replacement:
One thing replaces another thing.
Combustion Which of the following are common to all of the combustion reactions shown?
Oxygen as a reactant Heat as a product Flame
Which scale
Scale B It rounds to the nearest thousands instead of the nearest tenth.
Buffer System
Since carbonic acid breaks down to donate a proton (an H+ ion), it is the acid. The bicarbonate that is formed is called a conjugate base. Bicarbonate (HCO3-) is called a conjugate base because in the reverse reaction, it can accept a proton (an H+ ion) to form the conjugate acid
Decomposition Select the single best answer below to describe decomposition:
Something breaks down into smaller parts.
What is the molarity of lead in this sample obtained from Aliya's house? Report your answer to 2 significant figures
Step 1. Find the moles in the solution: (0.0000028 g / 100 mL) x (1 mole / 267.21 grams) Step 2: Add the conversion factor for getting mL to L. (0.0000028 g / 100 mL) x (1 mole / 267.21 grams) x (1000 mL / L) = 0.0000001 M
Mode 2 - Which of the following scenarios, if found to be true, might be cause for filing a suit against the hospital? (Choose all that apply)
The hospital gives a dose less than the safe dosage range
Tyler multiplied and his calculator gave him the number 1564.92, which he rounded to 1560 grams. Why?
The original measurement has 3 singificant figures so the answer has 3 significant figures
Why would water be attracted to NaCl? Check all that apply.
The oxygen in water is attracted to the positively charged sodium ion. The hydrogen atoms of water are attracted to the negatively charged chloride ion.
Dimensional Analysis (factor-label method) Convert one set of units into another Match each conversion factor to its corresponding fraction What is the problem here?
We were given the dosage in grams and the medication is given out in mL
Air is a homogeneous mixture of different gases and therefore can also be classified as a solution. The composition of air is roughly 77 % N2, 20 % O2, 1 % Argon and some other trace gases like carbon dioxide. What is the solute(s) in air? Check all that apply
trace gases Ar gas N2 gas O2 gas (WRONG) New - O2 gas, Ar gas, Trace Gases
By definition, Juan's measurement is not an exact number. It has an ? of +-0.001. This means the powder has a weight between 19.657 and 19.659. All of the digits (non-zero numbers) are considered ?
uncertainty significant
If the pH of a solution is 0.8, what is its hydronium ion concentration? Express answer with 1 significant figure
0.2
Review 3 Let's say you wanted to calculate the density of a liquid to see if it will float on top of water. The mass of the liquid is 5.5 grams, and the volume of the liquid is 26 mL. If density is mass divided by volume, which of the answers below would be correct? Select all that apply
0.21
The mass of the liquid is 5.50 grams, and the volume of the liquid is 26 mL. If density is mass divided by volume, which of the answers below would be correct?
0.21
Perform the arithmetic and express your answer with correct significant figures: (1.20 + 3.69) ÷ 8.0 = ________________
0.61
Calculate the number of moles of NaCl contained in 0.500L of a 1.5M solution.
0.75 https://newshamchem.weebly.com/uploads/2/2/0/3/22035226/molarity_&_worksheet_answer.pdf
What is the molar concentration of 1.0 mol of KCl dissolved in 750. mL of solution?
1.03 (WRONG) New - 1.3
1.36 x 104 cm is equal to _______ km
1.36 x 10^1 (WRONG) New - 1.36 x 10-1
How much water (in mL) would need to be added to a 7 gram sample of iron to create a 7 ppb solution?
1000000000
A swimming pool has a volume of 7200 gallons. What is this volume in cubic centimeters (cm3; hint 1 mL is equal to 1 cm3)
2.7 x 10^7
A + BC > AC +B Based on this, which of the reactions below are single-replacement reactions?
2Al + Fe2O3 > Al2O3 + 2Fe 2Al + 3CuO > 3Cu + Al2O3
Which is the base in the reaction below? 2NH3 + H2SO4 à SO4-2 + 2NH4+
2NH3
AB > A + B Based on this, which of the reactions below are decomposition reactions?
2NI3 > N2 + 3I2 Na2CO3 + heat > Na2O + CO2 2HgO + heat > 2Hg + O2
Multiply and express your answer with the correct number of significant figures: 10500 cm x 3.10 cm =
32600 cm2
Select all of the reactions below that represent a redox reaction.
4 C5H9O + 27 O2 à 20 CO2 + 18 H2O P4 + 3 O2 à 2 P2O3 SeCl6 + O2 à SeO2 + 3Cl2 2 C5H5 + Fe à Fe(C5H5)2 CaCO3 à CaO + CO2 2 AgNO3 + Cu à Cu(NO3)2 + 2 Ag 2 NH3 + H2SO4 à (NH4)2SO4 Pb + FeSO4 à PbSO4 + Fe C3H6O + 4 O2 à 3 CO2 + 3 H2O C8H16 + 12 O2 à 8 CO2 + 8 H2O 2 NO2 à 2 O2 + N2 O3 à O + O2 3 Pb + 2 H3PO4 à 3 H2 + Pb3(PO4)2 (WRONG)
Phenol (toxin) is produced by a single-replacement reaction, shown below. What pattern do single-replacement reactions follow? H+ + C6H5ONa → C6H6O + Na+
AB + C → AC + B
A double-replacement reaction for the creation of hydrogen cyanide is shown below. What pattern do these reactions follow? AgCN(aq)+ HNO3(aq) → HCN(g) + AgNO3(aq)
AB + CD → AD + BC
Double-replacement reactions follow the following general pattern: AB + CD = AD + CB Based on this, which of the reactions below are double-replacement reactions?
BaCl2 + Na2SO4 > BaSO4 + 2NaCl Pb(NO3)2 + 2KI > 2KNO3 + PbI2
Based on these images, what can you say about bases? Select all that apply.
Bases dissociate into OH- ions in water The dissociation of a base generates a positive and negative ion.
Why is weighing the sample needed to find the number of moles in this case?
Because we need to know the mass of the sample to calculate the moles of the sample
A + B > AB Based on this, which of the reactions below are combination reactions?
Fe + S > FeS MgO + CO2 > MgCO3 CaO + H2O > Ca(OH)2
Select all of the reactions below that represent a combustion reaction.
C8H16 + 12 O2 à 8 CO2 + 8 H2O 4 C5H9O + 27 O2 à 20 CO2 + 18 H2O C3H6O + 4 O2 à 3 CO2 + 3 H2O
Using your knowledge of the Brønsted-Lowry theory of acids and bases, predict the formula of the conjugate base of the reaction below. CH3NH2 + H2O à *where CH3NH2 is the base
CH3NH2 + H2O > CH3NH3 + OH-
3.12 inch + 4.90 inch + 6 inch
14 inch
Select all of the reactions below that represent a decomposition reaction.
CaCO3 à CaO + CO2 2 NO2 à 2 O2 + N2 O3 à O + O2
You and a friend need to find the density of a metal in the lab. The metal has a weight of 23.2 grams and a volume of 8.593 mL. You calculate the density as 2.67, and your friend calculates the density as 2.69987199. Which is the better response? Why?
My calculation is the better response because the answers contain the same number of significant figures as the number in the equation with the fewest significant figures
Based on your findings from above, how does your hypothesis hold up?
My hypothesis is supported by my findings.
Which is the conjugate acid in the reaction below? 2NH3 + H2SO4 à SO4-2 + 2NH4+
NH4+
Which of the following best categorizes ammonia?
Neither
Combination Reactions
Two or more things come together to make a single larger thing.
A medicine is available in liquid form and is prescribed at 1 mL per 15 pounds of body mass. How many mL of the medicine should a 65 Kg patient receive?
none of the above (WRONG) New - 9.5
Which of the following substances is NOT a solution?
none of the above. they are all solutions (WRONG)
Perform the arithmetic and express your answer with correct significant figures: 0.100 + 0.7 - 7.35 = ________________
-6 (wrong) New: 6
Select all of the measurements that contain 3 significant digits.
0.00650 13.1
Calculate the molarity of 29.25 grams of NaCl in 2.0 liters of solution
0.25
200 g is equivalent to how many pounds?
0.4
A substance with a pH of 3 is how many times more acidic than a substance with a pH of 7? A substance with a pH of 10 is how much more basic than a substance with a pH of 2.
10000 more acidic 100000000 more basic
Select all of the reactions below that represent a combination (synthesis) reaction.
2 C5H5 + Fe à Fe(C5H5)2 2 NH3 + H2SO4 à (NH4)2SO4 P4 + 3 O2 à 2 P2O3 (WRONG)
Perform the arithmetic and express your answer with correct significant figures: 15.76 ÷ 3.69 = ________________
4.27
Addition and Subtraction Let's take a moment to practice. Report the following answers to the correct number of significant figures. 2.3 + 2.336 = 658.36 - 2.36899 = 2.3 x 2.336 = 658.36 ÷ 2.36899 =
4.6 655.99 5.4 277.91 both of your answers contain the same number of significant figures as the number in the equation with the fewest significant figures
In other words, what units is the medication going to be delivered in? I want to convert 0.1 g of dilantin to ? of ?
? - milliliters ? - dilantin
Take a look at the combustion reaction involving bufotenin below. What pattern do combustion reactions follow? C12H16N2O(s) + 15.5 O2(g) → 12 CO2(g) + 8 H2O(g) + N2(g)+ Heat
AB + O2 → AOx + BOy
summary
Answers contain the same number of significant figures as the number in the equation with the fewest significant figures
Based on what you see in the charts, which of the following do you believe is true?
Areas with higher water lead level (WLL) had higher incidences of children with elevated blood lead levels. There is evidence to suggest that switching to the Flint River increased the blood lead levels of citizens in the city.
Considering your properly drawn Lewis dot structure and what you know about polarity and "like dissolves like", select all of the compounds that are miscible with hexanes, C6H14.
CH4 , CO2, NH3 (WRONG)
Which is the conjugate base in the reaction below? HCl + H2O à H3O+ + Cl-
Cl
Select all of the kinds of reactions that can be redox:
Decomposition Combination Single Replacement Combustion
Remember that Brønsted-Lowry acids are H+ donors and Brønsted-Lowry bases are H+ ion acceptors. Some substances might also fit the Arrhenius acid-base model.
HCl is a(an): Arrhenius & Bronsted Acid NH3 is a(an): Bronsted Only base CH3NH2 is a(an): Bronsted Only base
Based on this simulation, what is true of bases? Select all that apply.
When a strong base dissociates, the concentration of the strong base in the solution becomes negligible. Strong bases completely dissociate into M+ (metal cation) and OH- Strong bases dissociate to form more hydroxide ions than a weak base.
Did the hospital crew administer a dangerous dose to Tiffany's twins that may have caused the side effects they witnessed?
Yes—because the hospital was supposed to give 1.36 mL not 20 mL to each twin
A black bear can run 35.0 miles per hour! How long would it take the bear to run 1.95 x 10 4 feet?
none of the above (WRONG) New - 0.360 (WRONG)
Determine Sig Figs The leading zeros in 0.00832407 are not significant because they come before the first nonzero figure. Trailing zeros are significant if the number contains a decimal point. All nonzero digits, as well as captive zeros, are significant 0.0058 500 500.0 89.305 help 0.08050
- 2 - 1 - 4 - 5 - 4
Select all of the reactions below that represent a double replacement reaction.
2 MgI2 + Mn(SO3)2 à 2 MgSO3 + MnI4 Na3PO4 + 3KOH à 3 NaOH + K3PO4 3 HBr + Al(OH)3 à 3 H2O + AlBr3 2 HBr + Ca(OH)2 à CaBr2 + 2 H2O RbNO3 + BeF2 à Be(NO3)2 + 2 RbF MgCl2 + Li2CO3 à MgCO3 +2 LiCl Li3N + 3 NH4NO3 à 3 LiNO3 + (NH4)3N
Calculating pH - pH = -log[H+] What is the relationship between H+ or H3O+ concentration and pH? Let's say the concentration of H+ ions in a patient's blood is 4.27 x 10-8 M, what would the pH of that blood sample be? Round your answer to the hundredths place
7.4
A pH of 7 indicates a/an ? solution. Substances with pH values lower than 7 are ? . Substances with pH values greater than 7 are ? .
? - neutral ? - acidic ? - basic
Dimethylmercury (toxin) can be produced by a combination reaction, shown below. What pattern do these reactions follow? Hg(l) + 2 C(s) + 3 H2(g) → Hg(CH3)2(l)
A + B → AB
What's common to all the reactions above? Select the best answer.
A single starting compound breaks down into other compounds.
The decomposition reaction below shows how sodium azide is broken down. What pattern do these reactions follow? 2 NaN3(s) → 2 Na(s) + 3 N2(s)
AB → A + B
Acid and Base: acid is a substance that can give up an H+. A base is a substance that can give up an OH- Using the definition above, select the acids from the list below: Using the definition above, select the bases from the list below:
Acids: HCl, H2SO4 Bases: NaOH, KOH
Select all of the reactions below that represent a single replacement reaction.
AgNO3 + Cu à Cu(NO3)2 + 2 Ag Pb + FeSO4 à PbSO4 + Fe 3Pb + 2 H3PO4 à 3 H2 + Pb3(PO4)2 SeCl6 + O2 à SeO2 + 3Cl2
What happens to H+ ions in water?
Aqueous (or a water-based) solution, free H+ ions are unlikely to be found. This is due to the charge on H+ ions which causes them to associate with water to form H3O+ or a hydronium ion. Acids dissociate into hydronium ions, H3O+. Overall, for solutions taking place in aqueous solutions, H+ and H3O+ represent the same thing
When metals corrode, as with rust, they lose electrons and become cations lost electrons (oxidized) and which has gained electrons (reduced).
Calcium started without a charge but became positively charged, meaning it lost electrons. When an element has lost electrons, it's said to have been oxidized. Calcium was oxidized. The H+ started out as positive and then ended up without a charge, meaning each hydrogen ion gained an electron. The hydrogen ions were reduced.
Hydrocarbon Combustion 3 main kinds of combustion reactions What's common to all the reactions above? Select the single best answer.
Compounds containing C and H react with oxygen gas to produce carbon dioxide, water vapor, and heat.
Match each chlorine containing acid to its name. Hydrobromic acid Perbromic acid Bromic acid Bromous acid Hypobromous acid
HBr, HBrO4, HBrO3, HBrO2, HBrO
The first fetal scalp blood test had a pH of 7.10. Now, the pH of the baby's blood is 7.08. What can we say about Priya's baby? Select all that apply.
Priya's baby is still hypoxic. The blood in the second sample is more acidic than the blood in the first sample. The labor and delivery team should consider intervening in the labor process.
Based on this simulation, what is true of strong acids? Select all that apply.
Strong acids have lower pH values than weak acids. When strong acids dissociate, the concentration of the strong acid in the solution becomes negligible. Strong acids completely dissociate into H3O+ (hydronium) and A- (conjugate base) leaving almost no strong acid in the solution. Strong acids dissociate to form more hydronium ions than a weak acid.
Describing Neutralization Reactions What's common to the reactions above? Select the best answer.
The acid gives up an , and a base gives an , forming water and a salt (ionic compound).
Acid Strength
The strength of an acid refers to that acid's tendency to dissociate or give up its proton. A strong acid will completely dissociate in a solution, but a weak acid will only partially dissociate. As an acid dissociates, the concentration of H+ ions in the solution increases. When the concentration of H+ ions in a solution increases, the pH of the solution decreases, and it becomes more acidic.
Base Strength
The stronger the base, the more willing it is to dissociate and give up OH- ions. When the concentration of OH- ions in a solution increases, the pH of the solution increases, and it becomes more basic. There are also weak acids and bases. They do not dissociate as readily as strong acids and bases.
What's common to the reactions above? Select the best answer.
Two or more reactants have combined to form a more complex product, a new compound.
How many grams of solute is there in 250. mL of a 0.10M CaCl2 solution?
0.0004(WRONG) New - 0.025
Select all of the measurements that contain 1 significant digits.
0.004
Calculate the molarity of 0.060 moles NaHCO3 in 1500. mL of solution.
0.040 M Explanation: In order to find molarity, you would first determine the number of moles of solute that are present, followed by the volume of solution (must be in liters). We already have the number of moles, so we just have to go from milliliters of solution to liters of solution. We do this by using the conversion factor: 1000 mL = 1 L. When you divide the 1500 mL that you're given by 1000 mL/L you obtain 1.5 L. Afterwards, you would simply divide the two like so: Molarity = moles of solute / liter of solution 0.060 mol NaHCO3 / 1.5 L of solution = 0.040 M.
Perform the arithmetic and express your answer with correct significant figures: 1.19 x 0.10 = ________________
0.12
The answer, 9.988 g, should be rounded to ________ g when considering significant figures (which you always should!).
10 g
Perform the arithmetic and express your answer with correct significant figures: 1.234 + 8.7 + 7.65 = ________________
18 (wrong)
1 tablet = 200 mg How many tablets equates to 400 mg?
2
8oz = 1 cup Let's say you have a recipe that calls for 16 oz, How many cups of do you need?
2 Cups If one cup is 8 oz, then two cups is 16 oz. Using common sense or logic.
Based on the samples collected from a number of homes in the area, lead levels of around ? were found. Because the action level of lead is ?, it is safe to say that the city must do something to treat the water and prevent corrosion of the city's pipes. Additionally, the blood lead levels of children are now higher than they were before the switch. Current blood lead levels in children are ? safe levels. This evidence supports the conclusion that lead poisoning is taking place and affecting the citizens of this city.
? - 28 ppb ? - 15 ppb ? - above
A molecule that would clean the oil off of birds is one that can dissolve in ?. Such a molecule has a ? tail, which is a long ? region. This region dissolves in ?. The molecule will also have a ? head, which contains an ion that allows the molecule to dissolve in ?. Such molecules are used in everyday items, such as ?
? - both oil and water ? - nonpolar ? - neutral ? - oil ? - polar ? - water ? - soaps
Thee number of tires on a car is an example of a/an ?; measuring it simply requires counting. Other values, such as the weight of a pencil, might contain some degree of ?. This is because the value reported by the scale might not match the true, exact value of the pencil. Scale A might report the weight as 5 grams, while scale B says the weight is 5.343 grams. Scale B contains more ?. Scales, like other measuring instruments, contain some level of uncertainty in the values they report. Some scales vary in their ? or how close the values they report are to the true value of the pencil. They can also vary in their ? or how close the various reported values are to each other.
? - exact numbers ? - uncertainty ? - sig figs ? - accuracy ? - precision
According the EPA report, ? and copper are leaking into the city's water supply. Both lead and copper can be considered ? dissolved in a solvent, which is ? in this case. This ? of water and dissolved heavy metals is a major public-health concern and could be a danger to ?.
? - lead ? - solutes ? - water ? - solution ? - all those drinking it
Oils are ? substances. An oil molecule would not likely dissolve in water because water molecules are ?. At a molecular level, water molecules are ? to each other than they are with oil molecules. This is why, when mixed together, water molecules stay together and oil molecules float on top.
? - nonpolar ? - polar ? - more attracted
Mod 3 A ? is made up a solute and a solvent. The more ? that is added to a fixed amount of ?, the ? concentrated the solution.
? - solution ? - solute ? - solvent ? - more
Each of the equations above shows how a particular acid (shown in red) behaves when in solution with water. What do all of these acids have in common? Select all that apply.
Acids are substances that dissociate into H+ ions in water. The dissociation of an acid generates a positive and negative ion.
Mod 5 What do you think you need to know in order to help? Select all that apply.
All of em
45.0 g of Ca(NO3)2 was used to create a 1.3 M solution. What is the volume of the solution in mL?
As we know that Molarity is given as, M = moles / V Solving for V, V = moles / M ------------------(1)Also, moles is equal to, moles = mass / M. mass -------------(2)puting value of moles from eq. 2 into eq. 1, V = (mass / M.mass) / MPutting values, V = (45 g / 164 g/mol) / 1.3 mol/dm³ V = 0.21 dm³ (WRONG) New - 95.0
Considering your properly drawn Lewis dot structure and what you know about polarity and "like dissolves like", select all of the compounds that are miscible with ethanol, CH3CH2OH.
CH4, CH2O, CO2, CH3OH, NH3, HF (WRONG)
Considering your properly drawn Lewis dot structure and what you know about polarity and "like dissolves like", select all of the compounds that are miscible with water, H2O.
CH4, CH2O, CO2, CH3OH, NH3, HF(WRONG)
Video https://www.youtube.com/watch?v=RRNMyyNSE48
Ethane is a nonpolar molecule because it contains an equal distribution of electrons. We know this because we can compare the electronegativity of C and H and see that they are similar.
Exact vs. Uncertain Sort the following into the appropriate categories.
Exact number - 1 liter = 1,000 mL, # of people living in a house & apples in a basket Contains uncertainty - weight & height
Why is this not the best answer? Select all that apply.
His answer has too many significant figures. His answer should be reported to two significant figures.
Why do you think iodine is insoluble in water?
Iodine is held together with strong covalent bonds and lacks any significantly charged regions. The interactions between water and iodine are not strong enough to overcome these covalent bonds.
The polar regions of water attract the ions in NaCl, causing them to break out of their crystalline structure. The attraction between water molecules and the sodium and chloride ions is called an ion-dipole force (here, the ion is either a sodium cation or a chloride anion and water is the dipole).
Ion-Dipole Interactions
Compare these observations with what you know about water and predict whether isopropyl alcohol will dissolve in water.
Isopropyl alcohol will dissolve in water, because they are both polar molecules.
Which of the following is true of a molecule of isopropyl alcohol? Check all that apply.
It has no full positive or negative charge. It has a region of partial positive charge. It has a region of partial negative charge. It is a polar molecule. It is a dipole.
Which of the following characteristics of a particle may allow it to dissolve in water?
It is a water-soluble ion with a full charge
What does this mean for the molecule we are looking for?
It must have polar and nonpolar regions
Which of the following characteristics of a particle may allow it to dissolve in water?
It should have a polar region that concentrates electrons in a particular part of the molecule It could contain an area with a full charge such as an ion
Quiz Select the compounds below that are ionic.
Li2O, CrO2, CuI2, N2O, P4O10, CaO (WRONG)
Calculate the molarity of 34.2 grams of sugar, C12H22O11 in 500. mL of solution.
Molarity = moles of solute / liters of solution Molarity of sucrose solution = moles of sucrose / liters of solution Moles of sucrose = grams of sucrose / molar mass of sucrose (34.2 g sucrose / (342 g/1 mole) = 0.1 moles sucrose Molarity of sucrose solution = moles of sucrose / liters of solution 0.1 moles sucrose / 0.500 L solution = 0.2 M sucrose solution
Air is a homogeneous mixture of different gases and therefore can also be classified as a solution. The composition of air is roughly 77 % N2, 20 % O2, 1 % Argon and some other trace gases like carbon dioxide. What is the solvent(s) in air? Check all that apply
N2 gas
Based on the images below, try to deduce a principle that can help determine which substances can dissolve in which. Select all that apply.
Polar substances dissolve in polar substances. Nonpolar substances dissolve in nonpolar substances.
The pH range for a healthy baby's blood is 7.18-7.38. Priya's baby's blood has a pH of 7.10. Based on this result, what can we say about Priya's baby? Select all that apply.
Priya's baby is hypoxic and isn't getting enough oxygen. Priya's baby's blood is more acidic than what is normal for a healthy human. The labor and delivery team should consider intervening in the labor process.
How many grams of sodium fluoride should he add to create this 4.0 M solution?
Step 1. Find the moles. Moles = molarity x liters of solution (4 moles / L NaF) x (0.5 L solution) = 2 moles Step 2: Find the grams. (2 moles NaF) x (42 g NaF / 1 mol NaF) = 84 grams
Let's say a sample was collected from a local water treatment plant. The 100 mL sample contained 0.000450 grams of sodium fluoride. What would the concentration of this sample be? The EPA considers concentrations that are greater than 0.000095 M to be cause for concern. Would this sample exceed that limit?
Step 1. Find the moles. Start with the units you have and multiply by the conversion factor given. Make sure your grams will cancel out by putting grams on the bottom. (0.00045 g / 100 mL solution) x (1 mol NaF / 42 grams NaF) = 0.00001071 moles NaF. Step 2: Find the molarity: (0.00001071 moles NaF / 100 mL solution) x (1000 mL / 1 L) = 0.000107 M yes
When an ionic substance is added to water it dissociates, i.e. breaks apart, because:
The positive regions of water are attracted to the cations of the ionic compound (WRONG)
Mod 4 What do you think are reasons that oil spills like the Deepwater Horizon disaster are particularly harmful? Check all that apply. Why do you think cleanup crews can't use water to clean wildlife? Therefore, the molecule you're looking for should be one that...
They immediately endanger wildlife such as birds and turtles by covering them in oil. They cause serious economic losses to surrounding fisheries. They cause local tourism industries to incur losses. Spilled oil can contain toxic substances that can poison wildlife such as fish. Methods to clean the spill can sometimes pump thousands of gallons of potentially unsafe substances into the water. Water and oil do not "mix" enough for water to wash oil off. Mix with both
Why is the answer written with a significant zero after the 4? Your calculator didn't do that. You have two measured quantities: moles and volume. The moles has TWO sig. figs while the volume has THREE. Since this is a division problem, your answer must have the same number of significant figures as your least precise measurement.
Unless your problems specify the hydrate by name, don't worry about adding the water molecules to the chemical formula! That's above the scope of lesson but finding the formula of the copper(II)sulfate, its molar mass and using molarity as a conversion factor are 100 % within scope!
Now that you know that 50.5 grams of sucrose is equal to 0.147 moles of sucrose, we need to use this information to find the molarity (the unit of measuring concentration). We can calculate the molarity (M) or concentration of a solution in moles / L if we know the volume of the solution in liters (L). Let's say you mixed your 0.147 moles of sucrose into 0.0012 L of solution. Report your answer to 2 significant figures. What is the molarity of this solution?
You need to use the two values you are given to calculate the concentration (in molarity) of the sucrose in the solution. You know that there are 0.14 moles of sucrose in a 0.0012 liter solution. According to the equation for molarity, Molarity = moles of solute/liters of solution. Therefore, the molarity in this case would be 0.147 moles of sucrose / 0.0012 mL of solution = 122.5 molar solution.
In an aqueous solution, water is always the solvent. The solute can be any solid, liquid or gas that is miscible with water.
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