Gen Chem Test 4 Review

0.082 is for 8.314 is for

0.082 is for ATM 8.314 is for KPA

pressure @ sea level

1

4 steps in balancing half-reactions under acidic conditions:

1. balance all elements other than H and O 2. balance O by adding H2O as needed 3. balance H by adding H+ as needed 4. balance charge by adding e- as needed

balancing half rxns under basic conditions

1. follow same steps for acidic 2. for each H+ added, add the same number of OH. **Wherever there's a H+ and OH- on same side, combine to make H2O. Cross out excess H2O 3. balance charge by adding e- wherever 4. as needed, add integers to half-rxns to make number of moles of e- equal your half rxns

What is the molar solubility of BaF2 (Ksp = 1.8×10-7) in 0.10 M sodium fluoride? A. 1.8×10-5 M B. 1.8×10-7 M C. 1.8×10-9 M D. (1.8×10-7)1/2 M E. (1.8×10-7)2 M

A. 1.8×10-5 M

Adding sodium oxalate to a solution of oxalic acid causes the pH to A. increase due to the common ion effect. B. decrease due to the common ion effect. C. remain constant because the resulting solution is a buffer. D. increase due to shifting the Ka. E. decrease due to shifting the Ka.

A. increase due to the common ion effect.

water is always undergoing ....

AUTOIONIZATION Water spontaneously autoionizes into H+ and OH-.

An activated complex, also known as a _______ ________, is an unstable, high-energy state that briefly exists between a reactant and intermediate, or between a reactant and product. It exists at the ______ of the hill in the reaction coordinate diagram.

An activated complex, also known as a transition state, is an unstable, high-energy state that briefly exists between a reactant and intermediate, or between a reactant and product. It exists at the peak of the hill in the reaction coordinate diagram.

When the following reaction is balanced in acidic solution using whole number coefficients, what is the coefficient of H+?CrO42- → Cr2O72- A. 1 B. 2 C. 3 D. 4 E. 5

B. 2

Which process would be used to separate two miscible liquids? A. Filtration B. Distillation C. Decantation D. Disproportionation E. Crystallization

B. Distillation

Which of the following compounds would have Lewis dot diagrams constructed with the same number of valence electrons as NH4+? A. NO3- B. H2O C. CN- D. SO3 E. BF3

B. H2O The total number of valence electrons in NH4+ is: 5 + 4 - 1 = 8. The only compound that also has eight valence electrons is H2O, with six valence electrons from the oxygen, and one valence electron from each of the two hydrogens.

A real gas is most likely to exhibit ideal gas behavior under which of the following conditions? A. High temperature and high pressure B. High temperature and low pressure C. Low temperature and high pressure D. Low temperature and low pressure E. Real gases will never exhibit ideal gas behavior

B. High temperature and low pressure

Why does a nucleus weigh less than the sum of its neutrons and protons? A. Neutrons have negligible mass B. Some of the nucleus's mass is converted into nuclear binding energy C. The repulsive force between the protons and neutrons decreases the mass of the nucleus D. The combined mass of an atom's electrons is subtracted to determine nuclear mass E. Atoms in nature have lower masses due to long-term radioactive decay

B. Some of the nucleus's mass is converted into nuclear binding energy

B. Total energy decreases. Average kinetic energy _________ with increasing temperature. C. Enthalpy is constant. Enthalpy also changes with increasing ________. E. Activation energy decreases. The activation energy is ________ to the reactants, not to the temperature of the reaction.

B. Total energy decreases. Average kinetic energy increases with increasing temperature. C. Enthalpy is constant. Enthalpy also changes with increasing temperatures. E. Activation energy decreases. The activation energy is inherent to the reactants, not to the temperature of the reaction.

If a liquid is found to have weak intermolecular forces, then that liquid will generally have a A. low volatility. B. low viscosity. C. high density. D. high boiling point. E. high surface tension.

B. low viscosity.

H2O2 (34 g/mol) decomposes into water vapor and oxygen gas. How many liters of water vapor are produced from the decomposition of 17.0 g of H2O2 at STP? A. 2.8 B. 5.6 C. 11.2 D. 22.4 E. 44.8

C. 11.2

To separate a homogeneous mixture of salt water, which of the following pieces of laboratory equipment is necessary? A. Buret B. Pipet C. Condenser D. Filter E. Separatory funnel

C. Condenser

Which of the following would be the empirical formula of a compound that has 16 moles of oxygen and 56 moles of nitrogen? A. N56O16 B. N20O6 C. N7O2 D. N24O8 E. N32O16

C. N7O2 16/16 moles of oxygen = 1 mole oxygen 56/16 moles of nitrogen = 3.5 mole nitrogen This produces the empirical formula N3.5O. Elements combine to form compounds using whole number ratios, so multiply the subscripts by 2, resulting in N7O2.

Which of the following elements reacts explosively with water? A. Lead B. Iodide C. Potassium D. Hydrogen E. Argon

C. Potassium

What is the mass percent of methanol in a solution prepared by diluting 16 grams of methanol with 32 grams of water? A. 8% B. 16% C. 25% D. 33% E. 50%

D. 33%

What is an activated complex? A. A molecule that fully dissociates in solution. B. A molecule that contains electrically neutral groups of atoms held together by covalent bonds. C. A molecule that contains unpaired electrons in the molecular orbital diagram and is attracted to a magnetic field. D. An unstable arrangement of atoms that exists momentarily at the peak of the activation energy barrier.

D. An unstable arrangement of atoms that exists momentarily at the peak of the activation energy barrier.

Which of the following is an example of a compound that has polar bonds but is non-polar overall? A. SO2 B. H2O C. N2 D. CF4 E. NH3

D. CF4

With increasing temperatures, which of the following occurs? A. Entropy decreases. B. Total energy decreases. C. Enthalpy is constant. D. Entropy increases. E. Activation energy decreases.

D. Entropy increases.

__________ is the process to remove the top layer of liquid after the precipitate has settled at the bottom

Decantation is the process to remove the top layer of liquid after the precipitate has settled at the bottom

Calculate the work done by an ideal gas on its surroundings when the gas is heated at constant pressure of 1 atm from volume 50L to 100L at 298K. A. 10 L•atm B. 100 L•atm C. -0.821 L•atm D. -150 L•atm E. -50 L•atm

E. -50 L•atm

Consider the following reduction half-reactions: Which of the following is the Eº cell for the reduction of chlorine? A. -0.28 + 1.36 B. -0.28 + -1.36 C. -1.36 D. 0.28 E. 0.28 + 1.36

E. 0.28 + 1.36 have to flip the equation w/ Ni b/c need to use the e- from its OXIDATION to reduce Cl

What is the pH of a solution prepared by adding 20 mL of 0.02 M NaOH(aq) to 20 mL of water? A. 2 B. 3 C. 10 D. 11 E. 12

E. 12

What is the maximum number of electrons that can be held in the 4th energy level? A. 2 B. 8 C. 10 D. 14 E. 32

E. 32 The s orbital can hold a maximum of 2 electrons, the p orbital can hold a maximum of 6 electrons, the d orbital can hold a maximum of 10 electrons, and the f orbital can hold a maximum of 14 electrons. The 4th energy level can hold at most 2 + 6 + 10 + 14 = 32 electrons.

A solid compound that has a vapor pressure higher than atmospheric pressure will most likely be able to do which of the following? A. Melt B. Freeze C. Condense D. Vaporize E. Sublime

E. Sublime This is seen in dry ice. Dry ice has a higher vapor pressure than the atmosphere, thus as the dry ice "evaporates" the solid particles sublime.

In the reaction 2X + Y → X2Y, X is second order and Y is zero order. What would we expect to occur if [X] is tripled and [Y] is doubled? A. The rate would increase by a factor of 3 B. The rate would increase by a factor of 5 C. The rate would increase by a factor of 6 D. The rate would increase by a factor of 8 E. The rate would increase by a factor of 9

E. The rate would increase by a factor of 9 Evaluating 2X + Y → X2Y with X being second-order and Y being zero-order, we can leave out Y since changing the concentration of Y would have no effect on the overall rate of the experiment. Understanding the experiment is second-order overall, we then can interpret that the rate is proportional to the square of the concentration. Rate = [X]2, and we triple the concentration of X so Rate = [3X]2 = 9X2. So, if we triple the concentration of X, we multiply the rate by nine.

First-order reactions give a straight line with ______________ slope for the ___________________________ graph: Slope = -____ (units: _______) Example rate law: Rate = ????

First-order reactions give a straight line with negative slope for the ln[concentration] vs. time graph: Slope = -k (units: s-1) Example rate law: Rate = k[A]

Place the following elements in order of DECREASING ionization energy: Si, He, F, Cs

He --> F --> Si --> Cs Ionization energy is the energy needed to remove an electron. Ionization energy increases towards the top right of the periodic table.

Homogeneous mixtures are often separated using distillation. In distillation, the different ________ _______ of the substances are used to separate the mixture. The mixture is boiled, until one of the compounds evaporates. The evaporated compound is then immediately cooled through the ________ and collected on the other end in a flask.

Homogeneous mixtures are often separated using distillation. In distillation, the different boiling points of the substances are used to separate the mixture. The mixture is boiled, until one of the compounds evaporates. The evaporated compound is then immediately cooled through the condenser and collected on the other end in a flask.

KClO is dissolved in water. Which of the following reaction equations represents what is taking place throughout the solution? I. KClO → K+ + ClO- II. ClO- + H2O ⇌ HClO + OH- III. ClO- + H2O ⇌ HClO + H3O+ IV. H2O ⇌ H+ + OH-

I, II, and IV only When KClO is placed in water, it completely dissociates into K+ and ClO-. ClO-, as the conjugate base of HClO, will react with water to form HClO and subsequently partially dissociate back into H+ and ClO-.

Rank the following acids from lowest pKA to highest pKA: I. HF II. HCl III. HBr IV. HI

IV < III < II < I we'd expect HI to be the strongest acid (I has the largest atomic radius of the options), and HF to the weakest acid (F has the smallest atomic radius of the options). [Lowest pKa = strongest acid] HI < HBr < HCl < HF [Highest pKa = weakest acid]

In a ____________ reaction, a substance is simultaneously oxidized and reduced, giving two different products.

In a disproportionation reaction, a substance is simultaneously oxidized and reduced, giving two different products.

In _____________, a product is precipitated out, then is separated through filtration.

In crystallization, a product is precipitated out, then is separated through filtration.

IDEAL GAS LAW EQ:

PV=nRT P-pressure V-volume n-# of moles R- ideal gas constant (0.082) T- temp

Recall that all atoms must expend a certain amount of energy to keep their nuclei intact, which can be referred to as nuclear binding energy. We can also define nuclear binding energy as the amount of energy required in order to separate a nucleus into its constituent _________ and ______. The source of this energy is actually the nucleus itself, which uses mass as energy according to Einstein's famous equation: _________. Because mass is directly converted into energy, nuclear binding energy results in a ______ ______ , which means that the nucleus is not quite as heavy as the combined mass of the nucleus' protons and neutrons.

Recall that all atoms must expend a certain amount of energy to keep their nuclei intact, which can be referred to as nuclear binding energy. We can also define nuclear binding energy as the amount of energy required in order to separate a nucleus into its constituent protons and neutrons. The source of this energy is actually the nucleus itself, which uses mass as energy according to Einstein's famous equation: E = mc2. Because mass is directly converted into energy, nuclear binding energy results in a mass defect, which means that the nucleus is not quite as heavy as the combined mass of the nucleus' protons and neutrons.

Second-order reactions give a straight line with ____________ slope for ________________ graph: Slope = ____ (units: ________) Example rate law: Rate = ________

Second-order reactions give a straight line with positive slope for 1/[concentration] vs. time graph: Slope = k (units: M-1s-1) Example rate law: Rate = k[A]2

The group ___ elements, ____________, react vigorously with water to produce hydrogen gas. The group ___ elements, ______ ______, also react with water. However, they do not react as vigorously as the alkali metals.

The group 1 elements, alkali metals, react vigorously with water to produce hydrogen gas. The group 2 elements, alkaline earth metals, also react with water. However, they do not react as vigorously as the alkali metals.

The two liquids can be boiled to separate them. Liquids that are able to mix in all proportions are said to be __________. Miscible liquids form ______________ mixtures that can only be separated by exploiting the differing chemical properties of the two liquids.

The two liquids can be boiled to separate them. Liquids that are able to mix in all proportions are said to be miscible. Miscible liquids form homogeneous mixtures that can only be separated by exploiting the differing chemical properties of the two liquids.

This is critical to remember, only _________ can change the Ka. Changes in concentration will not change the Ka. Ka stands for acid dissociation constant, therefore this value stays constant and only changes if you change the temperature.

This is critical to remember, only temperature can change the Ka. Changes in concentration will not change the Ka. Ka stands for acid dissociation constant, therefore this value stays constant and only changes if you change the temperature.

Volatility is a liquid's readiness to evaporate. A liquid with _____ intermolecular forces will evaporate easily, and have high volatility. ________ is not related to intermolecular forces. ________ intermolecular forces lead to a low boiling point. The ________ the intermolecular forces, the higher the surface tension.

Volatility is a liquid's readiness to evaporate. A liquid with low intermolecular forces will evaporate easily, and have high volatility. Density is not related to intermolecular forces. Weak intermolecular forces lead to a low boiling point. The stronger the intermolecular forces, the higher the surface tension.

When the system does work on the surroundings, work is __________ and energy is lost. Alternatively, if the surroundings do work on the system, work is _________ and the energy is gained.

When the system does work on the surroundings, work is negative and energy is lost. Alternatively, if the surroundings do work on the system, work is positive and the energy is gained.

Zero-order reactions give a straight line with ______________ slope for the ___________________________ graph: Slope = _____ (units: _____) Example rate law: Rate = ????

Zero-order reactions give a straight line with negative slope for the [concentration] vs. time graph: Slope = -k (units: M1s-1) Example rate law: Rate = k

UNITS OF RATE LAWS

zero: M1M-1 first: s-1 second: M-1s-1