AP Chem - Unit 12 Test

Based on the knowledge of viscosity and bonding, which of the following would be the MOST viscous? (The molecules' bond lengths are not drawn to scale.) (if photo is not showing up go to # question 4)

A

Is used to explain why the boiling point of HF is greater than the boiling point of HBr A) Hydrogen bonding B) Hybridization C) Ionic bonding D) Resonance E) London dispersion forces

A

The boiling point of a substance is based on the intermolecular and intramolecular forces which in turn determine the lattice energy of a substance. Which of the following substances would have the highest melting point? A) AIF↓3 B) O↓2 C) Hg D) H↓2^O

A

When a liquid is present in an evacuated, sealed container, some of the liquid molecules escape the liquid phase and enter the gas phase above the liquid, as represented in the diagram. (if photo is not showing up go to question 4) When the liquid is heated, the vapor pressure increases. Which of the following containers shows the best representation for the reason for the direct relationship between the temperature of the liquid and its vapor pressure?

A

11. Substance A is made up two components, O and P. A small sample of substance A was dotted onto chromatography paper, and a chromatogram was developed using an appropriate solvent. The result is shown below. Component O is adsorbed . . . (if photo is not showing up go to question 11) A) less strongly onto the stationary phase and has a larger R value than component P. B) more strongly onto the stationary phase and has a smaller Rf value than component P. C) less strongly onto the stationary phase and has a smaller R value than component P. D) more strongly onto the stationary phase and has a larger R value than component P.

B

5. Which of the following would have the lowest melting point? (Note: It's in your best interest to add in the missing lone pairs) (if photo is not showing up go to question 5)

B

A student is given two covalent solids: stearic acid and glucose and is asked to determine the melting points of the two solids, which are listed in the table above. The student was perplexed by his observation that the glucose melted at a much higher temperature than did the stearic acid, even though glucose has a lower molar mass. What is the best explanation for his observations? (if photo is not showing up go to question 17) A) A high melting point indicates strong intermolecular forces. The forces between stearic acid molecules are stronger than the forces between glucose molecules. B) A high melting point indicates strong Intermolecular forces. The forces between glucose molecules are stronger than the forces between stearic acid molecules. C) A high melting point indicates weak intermolecular forces. The forces between stearic acid molecules are weaker than the forces between glucose molecules. D) A high melting point indicates weak intermolecular forces. The forces between glucose molecules are weaker than the forces between stearic acid molecules

B

A teacher directed students to set up a device with a battery, graphite electrodes connected to the battery with wires, and a dilute aqueous solution of a salt in order to illustrate a chemical principle. At the end of the experiment, students discovered that they had collected hydrogen gas in one test tube and oxygen gas in another. What type of change is this, and which reason best describes what happened at the particle level? (if photo is not showing up go to question 19) A) chemical change, the intermolecular forces between the water molecules were broken B) chemical change, the intramolecular forces between the hydrogen and oxygen atoms in water were broken. C) physical change, the intermolecular forces between the water molecules were broken D) physical change, the intramolecular forces between the hydrogen and oxygen atoms in water were broken.

B

Examine the properties for the four molecular substances shown in the table. Which non-polar substance would have the strongest intermolecular force? (if photo is not showing up go to question 10) A) I B) II C) III D) IV

B

Graphite and diamonds are made up of carbon atoms. Graphite, however, is soft and can be used to write, while diamonds are the hardest substances known to man and are the only substance that can be used to cut other diamonds. Which of the following is the main reason for this difference? A) The carbon atoms in graphite are covalently bonded while the carbon atoms in diamonds are made of ionic bonds. B) The bonds within a layer of graphite are much stronger than the attractions between the layers. C) The bonds in the layers of graphite are relatively weak, allowing for the atoms to slide past each other. D) The carbon atoms in graphite are covalently bonded while the carbon atoms in diamonds are held together by London dispersion forces.

B

In a laboratory activity, 50.0 mL samples of three different liquids (labeled A. B and C) were mixed. The contents of the beaker were stirred thoroughly, and the liquids were allowed to settle. After several minutes, the beaker appeared as shown in diagram liquids B and & formed a homogenous mixture at the bottom of the beaker while liquid A formed a separate laver on too of this solution. Which of the following statements best explains these observations? (if photo is not showing up go to question 22) A) liquid A forms strong intermolecular attractions with liquid B but not with liquid C. B) Liquid A does not form strong intermolecular attractions with either liquid B or liquid C. C) Liquids B and C have no strong intermolecular attractions for each other. D) Liquids A, B and C all form strong intermolecular attractions with each other.

B

Thin layer chromatography can be used to distinguish between different amino acids. If a particular amino acid has low solubility in the mobile phase used, then the amino acid . . . A) will spend more time dissolved in the mobile phase than attached to the stationary phase. B) will have a low Rf value C) will move at a speed close to that of a solvent D) must have a high molecular mass

B

Which of the following aqueous solutions will have the highest boiling point? A) 0.10 M NaCI B) 0.10 M Na2SO4 C) 0.10 M glucose D) 0.10 M sucrose

B

Which of the following is lower for a 1.0-molar aqueous solution of any non-volatile solute in water than it is for pure water alone? A) pH B) Vapor Pressure C) Boiling Point D) Electrical Conductivity

B

Which of the following pairs of compounds would exhibit only dipole-dipole attractions or London forces (.....no hydrogen bonding), for each other? (if photo is not showing up go to question 20) A) Methanol and hexane B) Chloroform and hexane C) Methanol and water D) Chloroform and water

B

A 5 L flask at a temperature of 500K contains a gaseous sample of helium (He), carbon dioxide (CO2), nitrogen (N2) and ammonia (NH3). Based on the information given, which of the following option provides the BEST prediction of the order in which the substances will condense if the flask was slowly cooled to -274°C? A) helium, nitrogen, carbon dioxide, ammonia B) nitrogen, carbon dioxide, ammonia, helium C) ammonia, carbon dioxide, nitrogen, helium D) ammonia, nitrogen, carbon dioxide, helium

C

A sample of ethanol is poured into a test tube containing water. The test tube is stoppered and shaken. The two substances do not chemically react with each other. The structures of water and ethanol in the attached table. Which of the following particle diagrams describes the test tube after it has been shaken and allowed to sit for ten minutes? (if photo is not showing up go to question 15)

C

A solution contains 28% phosphoric acid by mass. This means that . . . A) the density of this solution is 2.8 g/ml B) 1 mL of this solution contains 28 g of phosphoric acid C) 100 g of this solution contains 28 g of phosphoric acid D) 1 L of this solution has a mass of 28 g

C

DNA is very sensitive to environmental conditions. Some DNA is stronger than others depending on the number and type of certain base pairs in the DNA. DNA is made of the sugar ribose, a phosphate group, and four different nitrogenous bases: adenine, thymine, guanine, and cytosine. The two base pairs that occur in DNA are shown in the diagram. What type of DNA is stronger, DNA rich in adenine and thymine (A-T) base pairs or DNA rich in guanine and cytosine (G-C) base pairs and why? (if photo is not showing up go to question 18) A) A-T rich DNA, because it has more hydrogen bonding occurring between the nitrogenous bases. B) A-T rich DNA, because it has more dipole-dipole forces between its nitrogenous bases. C) G-C rich DNA, because it has more hydrogen bonding occurring between its nitrogenous bases. D) G-C rich DNA, because it has more london dispersion forces between its nitrogenous bases.

C

Intermolecular attractions between unlike molecules can form in a variety of ways, including the induction of a dipole in a nonpolar compound due to the presence of a nearby polar molecule. Which of the following pairs would exhibit this specific type of attraction, known as dipole-induced dipole attraction, as their main force of attraction between the unlike molecules if they were in solution with each other? (if photo is not showing up go to question 12)

C

Is used to explain why NaCI (s) has such a high melting point A) Hydrogen bonding B) Hybridization C) Ionic bonding D) Resonance E) London dispersion forces

C

Jewelers often use an alloy of gold, rather than pure gold, in order to make rings and necklaces reasonably priced and more durable. An example of such an alloy is 14-karat gold with the structure illustrated. Which of the following statements would properly identify the type of alloy 14-karat gold is and the properties the alloy would have compared to pure gold? (if photo is not showing up go to question 2) A) Interstitial alloy, it would be less malleable and ductile than gold because the silver atoms make the metal lattice more rigid. B) Interstitial alloy, it would be more malleable and ductile than gold because the silver atoms would disrupt the gold metal lattice. C) Substitutional alloy, it would be less malleable and ductile than gold because the silver atoms make the metal lattice more rigid. D) Substitutional alloy, it would be more malleable and ductile than gold because the silver atoms would disrupt the gold metal lattice.

C

The concentration of nitrate ion in a solution that contains 0.900 M aluminum nitrate is _______M. A) 0.450 B) 0.300 C) 2.70 D) 1.80 E) 0.900

C

Which of the following actions would be likely to change the boiling point of a sample of a pure liquid in an open container? I. Placing it in a smaller container I. Increasing the number of moles of the liquid in the container Ill. Moving the container and liquid to a higher altitude A) I only B) II only C) III only D) II and III only

C

Which of the following includes the best identification and explanation of the compound that this image may represent? (if photo is not showing up go to question 3) A) RbF; It is composed of ions in a 1:1 ratio and the ion sizes in the image demonstrate the small cation and large anion that compose this compound. B) MgCl2; It is composed of ions in a 1:2 ratio and the ion sizes in the image demonstrate the size difference between positive cations and negative anions. C) LiCI; It is composed of ions in a 1:1 ratio and the ions alternate to minimize repulsive forces. D) Brass, an alloy of copper cations and zinc anions; The smaller copper cations lie in between the larger zinc anions in a 1:1 ratio.

C

A liquid is placed into a thin glass tube and settles into a surface with an inverted meniscus in the form of an upside-down letter U. Which of the following is the best explanation for why this occurs? A) The nonpolar liquid molecules repel the nonpolar molecules of the tube. B) The liquid molecules have a very strong intermolecular forces holding the molecules together. C) In this instance there are no intermolecular attractions between the molecules of the liquid and the container whatsoever. D) The liquid is nonpolar, and its molecules more of an attraction to each other than with the polar molecules of the glass tube.

D

A solution with a concentration higher than the normal solubility is . . . A) saturated B) supercritical C) unsaturated D) supersaturated

D

During winter, lakes and ponds often freeze over in the northern latitudes. Fish survive the winter, so there must be some level of dissolved oxygen gas in their water to survive. If oxygen is to be dissolved in water, some form of attraction must exist between water molecules and oxygen molecules. Which would be the correct type of attraction? A) ion-dipole attraction B) dipole-dipole attraction C) hydrogen bonding attraction D) dipole-induced dipole attraction

D

In which of the following processes are covalent bonds broken? A) l2(S) >2(g) B) CO2(s) ›CO2 (g) C) NaCI(s) ›NaCI(l) D) C(diamond) ›C(g) E) Fe(s) Fe(l)

D

On first glance, table salt, NaCI, and the ordinary table sugar, sucrose C12H22011, appear very similar since both are white, crystalline solids. Tasting of chemicals in the laboratory is never an option, so it has not been included. Of the four possibilities listed below, which of the following would be a useful test to distinguish between table salt and sucrose. A) Smell the scent of the solids by dissolving in water and wafting your hand over the test tube. B) Test the pH of an aqueous solution of the substance. C) Test to see if the solid is soluble in water. D) Test electrical conductivity in aqueous solution.

D

Silicon carbide, SiC, is a solid with the structure illustrated above. Which statement below would best describe the melting point and hardness of SiC? (if photo is not showing up go to question 1) A) Low melting point and soft; solids with covalent bonds are not brittle and have lower melting points. B) Low melting point and hard; solids with covalent bonds have low melting points, but the covalent bond angles are fixed in the solid. C) High melting point and soft; a lot of energy would be needed to break the network of covalent bonds, but covalent solids are not brittle. D) High melting point and hard; a lot of energy would be needed to break the network of covalent bonds, and the covalent bond angles are fixed in the solid.

D

What is the molarity of sodium chloride in solution that is 13.0% by mass sodium chloride and that has a density of 1.10 g/mL? A) 1.43 x 10^-2 B) 2.23 C) 143 D) 2.45

D

When a liquid vaporizes into a gas, the pressure of that vapor is called "vapor pressure". Liquids are said to be "volatile" if they vaporize easily and these liquids would have a high vapor pressure. The vapor pressure of a liquid is related to its intermolecular forces, with substances having weak intermolecular forces having a high vapor pressure. A) the same because both molecules have the same molar mass. B) higher because isopropanol has more London dispersion forces. C) higher because ethyl methyl ether has more hydrogen bonding than isopropanol. D) lower because isopropanol has hydrogen bonding while ethyl methyl ether does not

D

When a sample of NaCl(s0 is dissolved completely in water, attractions are formed between Na+ and H2O. Which of the following identifies the name of this particular type of attraction and correctly represents the orientation of the particles in the diagram? (if photo is not showing up go to question 23)

D

Is used to best explain why iodine molecules are held together in the solid state A) Hydrogen bonding B) Hybridization C) Ionic bonding D) Resonance E) London dispersion forces

E