Chem quiz
What intermolecular forces are present between two molecules of CH₃OCH₂CH₃?
dispersion and dipole-dipole
Ammonia and hydrogen fluoride both have unusually high boiling points due to
hydrogen bonding.
Which of the following states of matter is pictured below?
solid
The reason an ionic bond forms can best be described as
the energy change for electron transfer results in a large gain in stability when the ionic bond forms.
form of energy
2 types of energy: Kinetic: solar radiant, electrical, wind, light, sound wave and thermal energy. Potential: chemical, gravitational, magnetic and nuclear energy.
Peanut Nutrition Fact: 160 Cal 28 g per serving Measured value = x= 4.52 Cal/g 4.52 Cal/g x 28 g =126.56 Cal/per serving
4.52 Cal/g x 28 g =126.56 Cal/per serving
What is the calorie equivalent of 562.0 J? (1cal = 4.184 J)
562.0 J x 1cal/4.184J =134.32 =134.0 cal
Identify the correct dipole for the C-Br bond in the Lewis structure of methyl bromide shown using the symbols δ⁺ and δ⁻.
A) (δ⁺)C - Br(δ⁻)
What is the difference between a gas and vapor?
A. a gas is a stable phase at temperatures greater than the boiling point of a liquid. A gas has one defined state at room temperature.
What are the top four elements found in the human body?
Answer: C, H, O, and N
Predict the chemical formula for the ionic compound formed by the elements Ca and Cl
CaCl₂
What is the difference between evaporation and boiling?
Evaporation occurs when a liquid becomes a gas at temperatures below that liquid's boiling point, whereas boiling is the conversion of a liquid to a gas at the liquid's boiling point.
Which of the following elements is the most electronegative?
F. fluorine
Which of the following is an example of a covalent bond?
H - Cl
is the transfer of energy from one body to another due to a difference in temperature.
Heat - is the amount of energy that is transferred from one system to its surroundings because of a temperature difference.
Classify the following compound as covalent (molecular) or ionic: LiBr
Ionic
Heat is an example of what type of energy?
Kinetic
Which of the following is not an example of a covalent bond?
Mg - N
Which of the following would you expect to have the highest boiling point?
NH₃
A Lewis structure for the molecule benzene (C₆H₆) is shown below. Based on this structure, determine if the molecule is polar or nonpolar.
Nonpolar
Draw the Lewis structure of O₂ and then determine if the molecule is polar or nonpolar.
Nonpolar
Draw the Lewis structure of carbon dioxide (CO₂) and then determine if the molecule is polar or nonpolar.
Nonpolar
Draw the Lewis structure of ethane (C₂H₆) and then determine if the molecule is polar or nonpolar.
Nonpolar
Which atom in the O-H bond has a partial negative charge (δ⁻)?
O
A Lewis structure for the molecule phenol (C₆H₅OH) is shown below. Based on this structure, determine if the molecule is polar or nonpolar.
Polar
Draw the Lewis structure of CSO and then determine if the molecule is polar or nonpolar.
Polar
Draw the Lewis structure of carbon monoxide (CO) and then determine if the molecule is polar or nonpolar. Please place the elements in the order that they are written.
Polar
Draw the Lewis structure of hydrogen peroxide (H₂O₂) and then determine if the molecule is polar or nonpolar.
Polar
Solvent:
The major component of a solution
Which of the following states of matter is pictured below?
liquid
Draw the Lewis structure of CBr₄ and then determine its electron domain and molecular geometries.
tetrahedral / tetrahedral
Find percent difference ? % difference= [measured value - theoretical value]/theoretical value x 100
% difference =[126.56 Cal - 160 Cal/ 160 Cal]= -20.9% it is absolute so even though its negative it will be postive.
Convert 23.4 kJ to calories.
23.4 KJ * 1000 J/ 1 KJ * 1 cal / 4.184 J =5590 cal
Convert 3.20 x 10 ^4 J to kilojoules.
3.20 x 10 ^4 J x 0.001 KJ/ 1 J =32.0 KJ
How many electrons are shared between two atoms in a triple bond?
6
Draw the Lewis structure of BrF₃ and then determine the ideal bonding angle(s) of the central atom.
90º
Heat is what?
=the movement of thermal energy from a substance at higher temperature to another substance at a lower temperature Heat is a form of energy that is transferred from a region of higher temperature to one of lower temperature
Which atom in the C-Br bond has a partial negative charge (δ⁻)?
Br
Which atom in the O-C single bond has a partial positive charge (δ⁺)?
C
Which is a covalent compound? A. Ethanol ( C2H6O) B. Dimethyl Ether ( C2H6O) C. BoTH A and B
C.
Identify the solvent in which C2H5OH will be most soluble. Explain why?
D. H2O
The compound NaBr is:
Ionic
True or False: Polar molecules have a significantly higher boiling point than nonpolar molecules.
True
What are the four major classes of biomolecules (Macromolecules) in the human body?
1. Carbohydrates 2. proteins 3. Fats (Lipids) 4. nucleic acids (DNA & RNA)
A light bulb consumes energy at a rate of 80.0 joules per second. How long in seconds will it take for thr light bulb to consume 2.30 x 10^5 J in energy?
2.30 x 10^5 J x 1 S/ 80.0 J= 2880 S
Convert 3.20 x 10^4 J to kilojoules.
3.20 x 10^4 J x 0.001 KJ/ 1 J = 32.0 KJ
He can push with a force of 500 N, and he work done for the final 40 m of displacement
500 N x 40 m = 20,000J
Which of the following represents an example of kinetic energy?
A ball rolling down a hill.
Which atom in the C-F bond has a partial negative charge (δ⁻)?
F
Based on the law of conservation of energy, the blank of potential and kinetic energy is constant.
Sum
Solute
The minor component of a solution
Which of the following is the correct Lewis symbol for a neutral atom of F?
image B, 7 valence electrons.
Which of the following is the correct Lewis symbol for a neutral atom of Al?
image c, has 3 valance electron
Work?
in physics, measure of energy transfer that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement. Work is done only when a force causes an object to move in the direction of the force. • Work Equation: Work = force x distance • W = F x d
Draw the Lewis structure of ethyne (C₂H₂) and then choose the appropriate pair of molecular geometries of the two central atoms. Your answer choice is independent of the orientation of your drawn structure.
linear / linear
Draw the Lewis structure of water (H₂O) and then determine its electron domain and molecular geometries.
tetrahedral / bent (109.5º)
Draw the Lewis structure of ozone (O₃) and then determine its electron domain and molecular geometries.
trigonal planar / bent (120º)
What is the work when a gas contracts from 4.66 L to 1.22 L under an external pressure of 3.97 atm? ➢Atmospheric pressure (atm), also known as barometric pressure, is the pressure within the atmosphere of Earth. ➢The standard atmosphere is a unit of pressure defined as 101,325 Pa, which is equivalent to 760 mm Hg, 29.9212 inches Hg, or 14.696 psi.
1,380 J Solution: First we need to determine the change in volume, ΔV. A change is always the final value minus the initial value: ΔV = Vfinal − Vinitial = 1.22 L − 4.66 L = -3.44 L Now we can use the definition of work to determine the work done: w = −Pext · ΔV = − (3.97 atm)( -3.44 L) = 13.7 L atm Now we construct a conversion factor from the relationship between liter·atmospheres and joules: 1L. atm = 101.32 J 13.7 L*atm x 101.32 J/1 L *atm = 1,380 J
Calculate the molarity of a solution made from 20.0 g of NaOH in 250 mL of solution. 1. Identify the known quantities and the desired quantity. known quantities: 20.0 g of NaOH and 250 mL of solution. desired quantity: ? M (mol/L)
2.0 M 2. Convert the number of grams of solute to the number of moles. Convert the volume to liters if necessary. 3. Use the molar mass to convert grams of NaOH to moles of NaOH (molar mass 40.0 𝐠/𝐦𝐨𝐥). 𝟐𝟎. 𝟎 𝐠 𝐍𝐚𝐎𝐇 × 𝟏 𝐦𝐨𝐥 /𝟒𝟎. 𝟎 𝐠 𝐍𝐚𝐎𝐇 = 𝟎. 𝟓𝟎𝟎 𝐦𝐨𝐥 𝐍𝐚𝐎H 4. Convert milliliters of solution to liters of solution using a mL-L conversion factor. 𝟐𝟓𝟎 𝐦𝐋 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧 × 𝟏 𝐋 /𝟏𝟎𝟎𝟎 𝐦𝐋 = 𝟎. 𝟐𝟓 𝐋 𝐬𝐨𝐥𝐮𝐭𝐢𝐨n. 𝐌𝐨𝐥𝐚𝐫𝐢𝐭𝐲 = 𝐌 = 𝐦𝐨𝐥𝐞𝐬 𝐨𝐟 𝐬𝐨𝐥𝐮𝐭𝐞 (𝐦𝐨𝐥)/ 𝐥𝐢𝐭𝐞𝐫 𝐨𝐟 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧 (𝐋) = 𝟎. 𝟓𝟎𝟎 𝐦𝐨𝐥 𝐍𝐚𝐎𝐇/ 𝟎. 𝟐𝟓 𝐋 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧 = 𝟐. 𝟎 M
A light bulb consumes energy at a rate of 80.0 joules per second. How long in seconds will it take for the light bulb to consume2.30 x 10^5 J in energy.
2.30 x 10 ^5 J X 1 S / 80.0 J = 2880 s
How many Joules are there in 30.0 kcal? (1 cal = 4.184 J)
30.0 kcal x 1,000 cal/ 1 kcal x 4.184 J / 1 cal = 1.26 x 10^5 J or 125520 J
Draw the Lewis structure of BeCl₂ and then choose the appropriate number of valence electrons on the central atom.
4
Convert 475 cal to joules.
475 cal * 4.184 J / 1 cal =1990 J
A particular beer is 6.50% ethanol by volume. If a single bottle of beer contains a total of 750.0 mL of beer, what volume, in mL of ethanol (C2H6O) are present in the bottle.
48.8 mL ethanol, 750.0 mL beer X (6.50 mL ethanol/ 100.0 mL beer)= 48.8 mL ethanol
What is the kilojoule equivalent of 54 cal?
54 cal x 4.184 joules x 1kcal/1000 cal = 0.225936=2.3 x10^-1
How many calories are in 5401 j ? ( 1 cal = 4.184 J)
5401 J * 1 cal / 4.184 J = 1.291 x10^3 cal
How many calories are 5401 J ? (1 cal = 4.184 J )
5401 J x 1 cal/ 4.184 = 1.291 x 10^3 cal
Concentrated:
A solution with a lot of solute
Dilute:
A solution with very little solute
Which of the following would exhibit hydrogen bonding in a pure substance?
CH₃CH₂OH
Which one of the following correctly ranks the compounds in order of lowest boiling point to highest boiling point based only in intermolecular forces?
D) CH₃CH₂CH₃ < CH₃OCH₃ < CH₃CH₂OH
Identify the correct dipole for the C-Br bond in the Lewis structure of methyl bromide shown using a vector arrow.
I
Draw the Lewis structure of water (H₂O) and then determine if the molecule is polar or nonpolar.
Polar
(True or False) he formation of a gas from a liquid at temperatures below the boiling point is called evaporation.
TRUE, - The formation of a gas from a liquid at temperatures below the boiling point is called evaporation.
Which of the following is an extensive property of the element carbon?
The mass of a carbon sample.
Solubility
The maximum amount of a solute that can be dissolved in a given amount of a solvent.
(T or F) One newton-meter is a unit used to measure both work and energy, it is also equal to one joule.
True 1 J = 1 Nm
A saline solution used in intravenous drips contains 𝟎. 𝟗𝟐% 𝐰Τ𝐯 NaCl in water. How many grams of NaCl are contained in 250 mL of this solution? 1. Identify the known quantities and the desired quantity. Known quantities 𝟎. 𝟗𝟐% 𝐰Τ𝐯 250 mL NaCl solution Desired quantity: ? g NaCl
Write out the conversion factors.: 𝟎.92% (𝐰/𝐯) NaCl in water 100mL solution/ 0.92 g NaCl = 0.92g NaCl /100 mL solution = 2.3 g NaCl
Which of the following states of matter is pictured below?
gas
A human is an example of a(n)
heterogeneous mixture
Suppose a student obtained the following data: mass of peanut half: 0.311 g mass of residue left: 0.010 g change of temp: 6.8 Celicus volume of water: 200.0 mL What is the caloric content, in Cal/ g of this peanut?
mass of peanut half = .311g - 0.010 g =.301 g heat = .20 L x 1.00 Cal/l x 6.8 = 1.36 1.36 Cal/.301 g= Answer: 4.52 Cal/g
What is the correct molecular geometry of NH₃ according to Valence Shell Electron Pair Repulsion Theory?
trigonal pyramidal (pyramidal)
Single, double, or triple covalent bonds in a carbon atom are formed from
valence electrons.
500.0 mL of a 0.200 M solution of LiBr is diluted to 700.0 mL. What is the new concentration of the solution?
0.143 M M1V1= M2V2 (0.200 M) x (500 mL) = (m2) X (700.0 mL) M2 = 0.200M x 500.0 mL/ 700.0 mL =0.143M
The molarity of a solution made by dissolving 2.00 moles of HCl in water is 2.65 M. What is the volume of the solution?
2.65 M = moles/L Known factors: 2.00 moles of HCl in water is 2.65 M 2.65 M = 2.00 moles/ L L= 2.00 moles/ 2.65 M = 0.7547L = 0.755L 0.755L x 1000 mL/1L = 755 mL
Only a certain amount of solute can be dissolved in a given amount of solvent. This maximum amount is called the _____ of the solute.
A. solubility
Calculate the percent composition of Cl of dichlorine heptoxide Cl2O7?
Answer: 38.76% Cl 70.90 g CL / 182.9OG X100%= 38.76% CL 112.00g O/ 182.90g x 100% = 61.24% O
Which one of the following is the correct set of Lewis Symbols for CaCl₂?
B) see problem image, The calcium ion its two valence electrons to have a 2+ charge. The chlorine ions each gain an electron to fill their octets and have a -1 charge.
Which of the following terms refer to the major component of a solution?
B. solvent
Which of the following is the correct Lewis symbol for the nitride ion?
C) see problem image, A neutral atom of N has 5 valence electrons. A nitride ion has a -3 charge, meaning it has 8 valence electrons.
Methylene chloride (dichloromethane, CH₂Cl₂) was once a common ingredient in many paint strippers. Based on its molecular formula, what kind of bonding does this compound exhibit?
Covalent only
Concentration
How much solute is dissolved in a given amount of solvent
Which of the following intermolecular forces are present in a pure sample of CH₃CH₃? I. Dispersion forces II. Dipole-dipole interactions III. Hydrogen bonding
I only
As a pure substance, which of the following could experience hydrogen bonding? I. H₂Se II. H₂O III. H₂
II only
Which of the following substances would not exhibit any hydrogen bonding interactions in a pure substance?
N(CH₃)₃
Which of the following exhibits dipole-dipole intermolecular forces in a pure substance?
NH₃
A Lewis structure for a different isomer C₂H₂F₂ is shown below. Based on this structure, determine if the molecule is polar or nonpolar.
Nonpolar
Which of the following is Not a form of potential energy?
Thermal
In a pure sample of CH₄, what forces of attraction exist between the molecules?
dispersion forces only
the 𝐰/𝐯 % concentration For example, vinegar contains 5 g of acetic acid in100 mL of solution, so the 𝐰/𝐯 % concentration is:
𝟓 𝐠 𝐚𝐜𝐞𝐭𝐢𝐜 𝐚𝐜𝐢𝐝/ 𝟏𝟎𝟎 𝐦𝐋 𝐯𝐢𝐧𝐞𝐠𝐚𝐫 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧 × 𝟏𝟎𝟎% = 𝟓% (𝐰/𝐯) 𝐚𝐜𝐞𝐭𝐢𝐜 𝐚𝐜𝐢d
if a bottle of rubbing alcohol contains 70 mL of 2-propanol in 100 mL of solution, then the 𝐯Τ𝐯 % concentration is
𝟕𝟎 𝐦𝐋 𝟐−𝐩𝐫𝐨𝐚𝐩𝐚𝐧𝐨𝐥 /𝟏𝟎𝟎 𝐦𝐋 𝐫𝐮𝐛𝐛𝐢𝐧𝐠 𝐚𝐥𝐜𝐨𝐡𝐨𝐥 × 𝟏𝟎𝟎% = 𝟕𝟎% (𝐯/v)