Chemistry Concepts: Heat, Gas Laws, Dilution

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Questions and Answers

Which of the following is the correct Lewis structure for the selenium difluoride molecule (SeF2)?

F Se F

F Se F (correct)

What is the correct ranking of the bonds in order of increasing polarity: N-H, Br-O, C-Cl?

C-Cl < N-H < Br-O

Br-O < C-Cl < N-H

N-H < C-Cl < Br-O

Br-O < N-H < C-Cl (correct)

What is the AXE classification for the SF2 molecule?

AX3E1

AX2E1 (correct)

AX2E2

AX3E0

What is the electron geometry around the central atom in the NO2- ion?

trigonal planar Signup and view all the answers

How many questions are included in this exam?

34 Signup and view all the answers

What should you do if a question on the exam appears ambiguous or unclear?

Raise your hand and ask for clarification Signup and view all the answers

What will happen if a student makes a mistake while using a pen on the bubble sheet?

There is no way to correct it Signup and view all the answers

What is the maximum number of points available on this exam before extra credit?

102 points Signup and view all the answers

What is the mass of the graphite sample if 312.5 cal of heat energy raises its temperature from 28.21°C to 76.87°C, given a specific heat of 2.036 cal/g°C?

6.055 g Signup and view all the answers

Which processes are correctly classified as endothermic or exothermic?

Condensation: exothermic, Sublimation: endothermic, Vaporization: exothermic Signup and view all the answers

During which segment of the heating curve is water in the solid state?

Below 0°C Signup and view all the answers

What is the pressure inside a 65.00 L tank containing 200.0 g of oxygen gas at a temperature of 75.00 °C?

1.373 atm Signup and view all the answers

What is the final concentration of a diluted cobalt chloride solution if 11.85 mL of a 6.345 g/L solution is diluted with 19.37 mL of water?

3.882 g/L Signup and view all the answers

Which statement accurately describes the phase of water during the phase change at 0°C?

Water can exist as a solid or liquid. Signup and view all the answers

What occurs during the process of sublimation?

Solid to gas without becoming liquid Signup and view all the answers

In the context of heating water, what happens at the boiling point?

Water changes from liquid to gas. Signup and view all the answers

What is the molecular shape of the NH3 molecule?

trigonal pyramid Signup and view all the answers

What is the molecular geometry of the SO2 molecule?

bent Signup and view all the answers

Which of the following correctly classifies CHF3, PF3, and CCl4 as polar or nonpolar?

polar, polar, nonpolar Signup and view all the answers

Identify the strongest intermolecular force acting in SO3, CH3OCH3, and PCl3.

dipole-dipole forces, hydrogen bonds, London dispersion forces Signup and view all the answers

Arrange the following substances in order of increasing boiling point: CH3OH, CH3F, CH3CH3.

CH3CH3 < CH3OH < CH3F Signup and view all the answers

Which intermolecular force is predominant in CH3OH?

hydrogen bonding Signup and view all the answers

Which molecule listed is nonpolar?

CCl4 Signup and view all the answers

Which molecular shape is associated with a molecule having a lone pair and three bonded pairs?

trigonal pyramidal Signup and view all the answers

What is the mass of 0.6027 mole of potassium sulfate?

197.7 g Signup and view all the answers

What mass of sodium has the same number of atoms as 15.00g of sulfur?

8.837 g Signup and view all the answers

What is the coefficient for O2 (g) when balancing the equation NH3 (g) + O2 (g) → NO (g) + H2O (g)?

2 Signup and view all the answers

Identify the formula of the precipitate formed from lead(II) nitrate and potassium iodide?

PbI2 Signup and view all the answers

What is the maximum mass of nitric acid that can be produced from 52.00g of H2O2?

192.7 g Signup and view all the answers

How many moles of copper(II) sulfate are present in 62.765 g of copper(II) sulfate?

2.543 mol Signup and view all the answers

Which of the following mixtures will produce a precipitate?

Ni(NO3)2 (aq) + Na2CO3 (aq) Signup and view all the answers

What is the boiling point order from lowest to highest for the following alcohols?

A.OH < B.OH < C.OH < D.OH < E.OH Signup and view all the answers

Which reaction will have the fastest rate in the forward direction when A(g) and B(g) are mixed at 0.500 M each?

Reaction B Signup and view all the answers

At equilibrium, which of the following statements must be correct?

The rate of the forward reaction equals the rate of the reverse reaction. Signup and view all the answers

Identify the correct equilibrium expression for this reaction: 4 CH4 (g) + S8 (s) ⇌ 4 CS2 (g) + 8 H2 (g).

$K = \frac{[CS2]^4 [H2]^8}{[CH4]^4}$ Signup and view all the answers

What will happen to the equilibrium when the temperature of the reaction N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g) is raised?

Shifts toward reactants Signup and view all the answers

What effect does adding more N2 have on the equilibrium of the reaction system N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g)?

Shifts toward products Signup and view all the answers

What happens to the reaction system when the volume is decreased?

Shifts toward the side with fewer gas molecules Signup and view all the answers

Which of the following conditions changes the rate of reaction without affecting the equilibrium constant?

Adding a catalyst Signup and view all the answers

Which statement about equilibrium concentrations is true?

Concentrations of reactants and products remain constant Signup and view all the answers

Study Notes

Specific Heat

The specific heat of graphite is 2.036 cal/g°C.
When 312.5 cal of heat energy are applied to a sample of graphite, the temperature of the graphite increases from 28.21°C to 76.87°C.
The mass of the sample of graphite is 13.08 g.

Endothermic and Exothermic Processes

Condensation is an exothermic process.
Sublimation is an endothermic process.
Vaporization is an endothermic process.

Heating Curve of Water

The heating curve of water shows the different phases of water present as heat is added.
During the segment of the curve indicated, the phase of water present is liquid only.

Gas Laws

200.0 g of oxygen gas are sealed in a 65.00 L tank at a temperature of 75.00 °C.
The pressure inside the tank is 2.747 atm.

Solution Dilution

A solution of cobalt chloride has a concentration of 6.345 g/L.
11.85 mL of this solution are diluted by adding 19.37 mL of water.
The final concentration of the diluted solution is 3.882 g/L.

Lewis Structures

The Lewis structure of selenium difluoride (SeF2) has the following arrangement:
- F Se F

Molecular Geometry and Polarity

The AXE classification for SF2 is AX2E2.
The geometry around the central atom in the NO2- ion is bent.
The molecular shape of the NH3 molecule is trigonal pyramid.
The molecular shape of the SO2 molecule is bent.
CHF3 is polar.
PF3 is polar.
CCl4 is nonpolar.

Intermolecular Forces

The strongest intermolecular force operating in SO3 is London dispersion forces.
The strongest intermolecular force operating in CH3OCH3 is dipole-dipole forces.
The strongest intermolecular force operating in PCl3 is dipole-dipole forces.

Boiling Point

The order of increasing boiling point for CH3OH, CH3F, and CH3CH3 is CH3CH3 < CH3F < CH3OH.

Stoichiometry

The mass of sodium that has the same number of atoms as 15.00g of sulfur is 8.837 g.
0.6027 mole of potassium sulfate has a mass of 105.0 g.
62.765 g of copper(II) sulfate contains 0.3932 mol.

Balancing Chemical Equations

The balanced chemical equation for the reaction of NH3 (g) and O2 (g) to form NO (g) and H2O (g) is:
- 4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (g)
The coefficient for O2 (g) in the balanced equation is 5.

Limiting Reactants and Stoichiometry

The maximum mass of nitric acid that can be prepared from 52.00 g of H2O2 and excess N2H4 in the reaction N2H4 (l) + 7 H2O2 (aq) → 2 HNO3 (aq) + 8 H2O (l) is 96.34 g.

Precipitation Reactions

The precipitate formed when aqueous solutions of lead(II) nitrate and potassium iodide are mixed is PbI2.

Reaction Energy Diagrams

The reaction energy diagram with the lowest activation energy will have the fastest rate in the forward direction.

Chemical Equilibrium

At equilibrium, the rate of the forward reaction and the rate of the reverse reaction are equal.
The equilibrium equation associated with the reaction: 4 CH4 (g) + S8 (s) 4 CS2 (g) + 8 H2 (g) is:

K= [CS2 ]^4 [H2 ]^8 [CH4 ]^4

Le Chatelier's Principle

The equilibrium will shift toward products when N2 is added to the reaction system N2 (g) + 3 H2 (g) 2 NH3 (g) ∆H = –22.1 kcal.
The equilibrium will shift toward reactants when the temperature is raised for the reaction system N2 (g) + 3 H2 (g) 2 NH3 (g) ∆H = –22.1 kcal.
The equilibrium will shift toward products when the volume is decreased for the reaction system N2 (g) + 3 H2 (g) 2 NH3 (g) ∆H = –22.1 kcal.

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Description

Test your understanding of key chemistry concepts including specific heat, endothermic and exothermic processes, the heating curve of water, gas laws, and solution dilution calculations. This quiz will challenge your knowledge and application of these fundamental topics in chemistry.