Ap chem

How many mL of 10.0 M HCl are needed to prepare 500. mL of 2.00 M HCl ?

100 mL

The volume of a gas collected when the temperature is 11.0°C and the pressure is 710 mm Hg measures 14.8 mL. What is the calculated volume of the gas at 20.0°C and 740 mm Hg?

14.7 mL

Which of the solids is a crystalline solid and which is an amorphous solid? ( A / B )

A is crystalline and B is amorphous

in .40 mol of H2 and .15 mol of O2 were to react as completely as possible to produce H2O what mass of reactant would remain

A. .20 g of H2

The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase?

A. The London (dispersion) forces increase.3

Which of the following is the balanced net ionic equation for the reaction between Li(s) and water?

B

A sample of a compound that contains only the elements C, H, and N is completely burned in O2 to produce 44.0 g of CO2, 45.0 g of H2O, and some NO2. a possible empirical formula of the compound is

B. CH5N

The structure of one form of boron nitride is represented above. This form of boron nitride is one of the hardest substances known. Which of the following best helps explain why boron nitride is so hard?

Boron nitride is a network solid of atoms connected by covalent bonds with fixed bond angles.

A 1.0 L sample of a pure gas is found to have a lower pressure than that predicted by the ideal gas law. The best explanation for the observation is that the molecules of the gas

C. are attracted to each other and do not exert as much force on the container walls as they would if they had no mutual attractions

The best explanation for the fact that diamond is extremely hard is that diamond crystals

C. are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms

Would C2H2 dissolve in water (H2O) or hexane (C6H14)? Explain.

C2H2 would dissolve into the hexane because both C2H2 are nonpolar while water is polar, causing the C2H2 to not want to dissolve into water.

a .20 mol of a sample of MgCl2 (s) and a .10 mol sample of KCL(s) are dissolved in water and diluted to 500mL what is the concentration of Cl-1 in the solution?

D. 1.0 M

At what set of conditions of temperature and pressure, will a gas behave most as a real gas?A. 1100 K and 1 atmB. 1100 K and 100 atmC. 250 K and 1 atmD. 250 K and 100 atm

D. 250 K and 100 atm

The diagram above is a molecular model of a gaseous diatomic element that is just above its boiling point. Intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. Which of the following best describes how the model is limited in its depiction of the phenomenon?

D. It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.

The electron cloud of HF is smaller than that of F2, however, HF has a much higher boiling point than F2 has. Which of the following explains how the dispersion-force model of intermolecular attraction does not account for the unusually high boiling point of HF?

D. Liquid F2 has weak dispersion force attractions between its molecules, whereas liquid HF has both weak dispersion force attractions and hydrogen bonding interactions between its molecules.

A 0.10 M aqueous solution of sodium sulfate, Na2SO4 , is a better conductor of electricity than a 0.10 M aqueous solution of sodium chloride, NaCl. Which of the following best explains thisobservation?

D. More moles of ions are present in a given volume of 0.10M Na2SO4 than in the same volume of 0.10 M NaCl.

The ionic compounds NaCl and MgS are represented by the diagrams above. Which statement correctly identifies diagram 1 and identifies the compound with the lower melting point, explaining why?

Diagram 1 represents NaCl; it has a lower melting point than MgS because the coulombic attractions between its singly charged Na+Na+ ions and the Cl− ions are weaker than those between the ions in MgS.

Is a strong electrolyte in aqueous solution

E. HBr(g)

In solid methane, the forces between neighboring CH4 molecules are best characterized as

E. London (dispersion) forces

Equal numbers of moles of CO2(g), N2(g), and NH3(g) are placed in a sealed vessel at room temperature. If the vessel has a pinhole-size leak, which of the following will be true after some of the gas mixture has effused? I. The mole fraction of CO2 in the sample will increase.II. The N2 will effuse the fastest since it is the lightest.III. All gases will effuse at the same rate since the temperature is held constant.

I. The mole fraction of CO2 in the sample will increase.

The diagram above is a molecular model of a gaseous diatomic element that is just above its boiling point. Intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. Which of the following best describes how the model is limited in its depiction of the phenomenon?

It does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.

If the molarity of magnesium nitrate is 0.25 M, what is the concentration of the magnesium ion and the nitrate ion?

Mg: .25M & NO3: .50M

Which statement best helps to explain the observation that NH3(l) boils at −28°C, whereas PH3(l) boils at −126°C?

NH3 has hydrogen bonding that is stronger than the dipole-dipole forces in PH3

Describe the orientation water around ions in CaCl2. Include the number of each ion you would need to draw so one formula unit of CaCl2 is correctly represented

The Ca+ would have the negative O atoms attached and the Cl- will have the positive H atoms attached from H2O. There would be one Ca ion and two Cl ions.

(b) Briefly explain how the presence of charged ions in ionic solids such as NaCl(s) helps to explain why NaCl(s) is soluble in water.

The anions and cations are attracted to the polar water molecule.

(c) Describe what happens to the average speed of the Xe atoms in the container in diagram 3 as the original volume V is reduced to V2 at a constant temperature. Explain.

The average speed will remain the same because the temperature is constant.

If the volume of a container is 1/3 of the size of the original container that has a pressure of 3 atm, what is the new pressure?

The new pressure is 9atm.

If the volume of a container is 1/2 of the size of the original container that has a temperature of 300 K, what is the new temperature when pressure remains constant?

The new temperature would be 600K because when the volume is decreased by half, the temperature would increase by doubling in heat.

What will happen to a flexible container filled with gas if the temperature is decrease?

The pressure of the gas would decrease because temperature and pressure are directly proportional

(c) What volume of 0.20MNaCl(aq) contains 10.0g of NaCl (molar mass 58g/mol)?

The volume would be 860mL

in which of the following compounds does sulfer have an oxidation state of +4

b. h2so3

beaker x and y each contain 1.o L of solution, shown above. a student combines the solutions by pouring them into larger previously empty beaker z and observes the formation of a white precipitant. assuming the volumes are additive , whitch of the following sets of solutions could be represented by the diagram above?

d.

during the course of the experiment, which of the following happens to the NO3- ions

d. they remain dissolved in the filtrate solution

Look at the two structural formulas and determine which one will have the lowest boiling point. Compound on the left or right. Explain. (C5H12)

the compound on the right because it has less surface area than the one on the left

What are two different ways to separate liquid mixtures?

two ways to separate liquid mixtures would be through chromatography and distillation

Based on the data in the table above, which of the following correctly predicts the relative strength of the attraction of Zn2+, Ca2+, and Ba2+ ions to water molecules in a solution, from strongest to weakest, and provides the correct reason?

A. Zn2+ > Ca2+ > Ba2+ because the smaller ions have a stronger coulombic attraction to water

At 298 K and 1 atm, Br2 is a liquid with a high vapor pressure, and Cl2 is a gas. Those observations provide evidence that under the given conditions, the

A. forces among Br2 molecules are stronger than those among Cl2 molecules

The ionic compounds and are represented by the diagrams above. Which statement correctly identifies diagram 1 and identifies the compound with the lower melting point, explaining why?

B. Diagram 1 represents ; it has a lower melting point than because the coulombic attractions between its singly charged ions and the ions are weaker than those between the ions in .

If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure?

C. Butane

Nonane and 2,3,4-trifluoropentane have almost identical molar masses, but nonane has a significantly higher boiling point. Which of the following statements best helps explain this observation?

C. The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane.

Four different liquid compounds in flasks at are represented above. The table below identifies the compounds. Flask C shows the most particles in the vapor phase. Which of the following is not shown in the model but best helps to explain why flask C must contain pentane?

C. The strength of the intermolecular forces between the particles in the liquids

A certain crystalline substance that has a low melting point does not conduct electricity in solution or when melted. This substance is likely to be

E. a molecular solid

(b) Let P and V represent the pressure and volume of the Xe(g) in the container in diagram 3. If a piston is used to reduce the volume of the gas to V2 at a constant temperature, what is the new pressure in the container in terms of the original pressure, P ?

The pressure will be double the original pressure.

How would you describe a network solid?

They are solids bonded together by strong covalent bonds. They usually will have a high melting point.

Why do we have solids, liquids and gases?

intermolecular forces and density