Explore BrainMass

General Chemistry

Explanation of melting point & boiling point deviations

I only need help on question 3. I have perfomed the labs for melting pt and boiling pt on the following four and only need help with question 3 acetonitrile (C₂H₃N): GIVEN MP = -45.5C, BP = 77.3C My results MP= -46.8 C, BP = 79.4 C benzene (C6H6) GIVEN

Molar solubility product of barium fluoride

Please help with the following problems. Provide step by step calculations for each. 5.[a] The molar solubility of barium fluoride, BaF2, is 7.5 x 10-3 M. Calculate the solubility product constant [b]Calculate the molar solubility of lead fluoride, PbF2 in water, Ksp = 2.7 x 10-8 6.Calculate the molar solubility of bism

PowerPoint Presentation on the Element Boron

BORON I am looking for someone who is knowledgeable with PowerPoint. I need help getting started with this project and knowing how to go about this. My classmates told me finding a scientific article is the hard part to this project, so I want someone to help me with that also. _______________________________________

General Chemistry Problems

10.40) Many gases are shipped in high-pressure containers. Consider a steel tank whose volume is 65.0L and which contains O2 gas at a pressure of 16,500kPa at 23°C. a. What mass of O2 gas does the tank contain? b. What volume would the gas occupy at STP? c. At what temperature would the pressure in the tank equal 150.0atm? d. W

Assorted General Chemistry Problems

8.20) a. The lattice energies of NaF and MgO are 910kJ/mol and 3795kJ/mol. Account for the difference in these two quantities. b. Account for the difference in lattice energies of MgCl2 (2326 kJ/mol) and SrCl2 (2127kJ/mol). 8.28) Calculate the lattice energy of CaCl2. Is this value greater than or less than the lattice energ

General Chemistry Problems

5.38) Consider the following reaction: CH3OH (g) ---> CO (g) + 2 H2 (g) deltaH = +90.7 kJ a. Is heat absorbed or evolved in the course of this reaction? b. Calculate the amount of heat transferred when 45.0 g of CH3OH (g) is decomposed by this reaction at constant pressure. c. For a given sample of CH3OH, the enthalpy change

Assorted General Chemistry Problems

1.28) a. A cube of osmium metal 1.500cm on a side has a mass of 76.31g at 25°C. What is the density in g/cm3 at this temperature? b. The density of titanium metal is 4.51g/cm3 at 25°C. What mass of titanium displaces 65.8mL of water at 25°C? c. The density of benzene at 15°C is 0.8787g/mL. Calculate the mass of 0.1500L of be

Solving 7 Chemical Equations

I desprately need help solving these chemical equations to help me to study for an exam. Rules for Solving Chemical Equations: 1. Write the chemical reaction in word form 2. Post your symbols 3. Post diatomics (for single units only) 4. Post oxidation numbers for compounds 5. Post subscription (for compounds onl

Assorted General Chemistry Problems

1) Given the following data table of average bond enthalpies, estimate the ΔH^rxn for the reactions 2H2+O2-- 2H2O Bond Average (kJ/mol) H-H 436 O=O 498 H-O 423 2) Draw eight distinct, valid Lewis resonance structures for the molecule XeO3. 3) Which structure or structures is or are mo

Assorted General Chemistry Problems

1) List the following gases in order of increasing root-mean-square speed, all at the same temperature: H2, He, O2, Ne 2) Under what conditions of pressure and temperature is a real gas most expected to deviate from ideal gas behaviour? 3) What intermolecular interactions would be the strongest between molecules CH2Cl2?

Molecular Geometry and Bond Order Problems

1) What is the molecular geometry of the ammonium ion? 2) What is the molecular geometry of the SO2Cl2 molecule? 3) What is the approximate F-S-F bond angle in sulfur hexafluoride? 4) What is the hybridization of the central atom in COCl2? 5) What is the hybridization of the central atom in selenium tetrabromide?

Light and Quantum Numbers

1) What is the molar concentration of a solution that is made by dissolving 6.30g of sodium chloride and diluting 1.00L?Report your answer to three significant figures. 2) In an experiment, 6.00g of Mg(s) was reacted completely with O2(g) to form MgO(s) and 148.5kJ of heat was evolved. What is the molar emthalpy of formation

Assorted General Chemistry Problems

1) In a combustion analysis, 2.00mg of vitamin C yielded 3.00mg CO2 and 0.816mg H2o. From mass spectrometry, it was found that the molecular weight of vitamin C is 176amu. Determine the mass composition of vitamin C, its empirical formula, and its molecular formula. 2) What is the energy of the photon that is emitted when the

Radius/Density From bcc and fcc Unit Cells

Krypton crystallizes as a fcc (face centered cubic unit cell) having an edge length of 559 pm. (a.)What is the density of solid Krypton? (b.) What is the atomic radius of a krypton atom? (c.)What is the volume of one krypton atom? Potassium crystallizes in a bcc (body centered cubic unit cell) structure. The atomic radi

Fission and isotopes

1a.) You have 16 electrons, 16 protons, and 16 neutrons. You can combine them to make 8 Helium (He-4) atoms, 4 beryllium atoms (Be-8), 2 oxygen atoms (O-16), or one sulfur atom (S-32). What will you do to make the most stable product? Info: H-1 1.00782505 amu He-4 4.0026033 amu Be-8 8.0053052 amu O-16

Chemistry Expressions

1. (a) Express 50 days in seconds (b) Convert 3.75 meter/sec to km/hr. Express the results in scientific notation. 2. Perform the following operations and express the answer with the appropriate number of significant figures. 863[1255-(3.45*10.8)] 3. The recommended dose of Elexophyllin (a drug used to treat

Packing of Particles in Solids-space Lattices

Hexagonal Closet Packaging vs. Cubic Closet Packaging (face-centered) vs. Body-centered a) Which of the three types of packaging has the least efficient arrangement of atoms? Justify the answer. b) How do the two more efficient forms of packing compare regarding volume? c) What is the relationship between coordination n

Chemical Bonding: Melting Point

1. Consider the following data: expect a BeF2 molecule to be linear but an SF2 molecule to be angular. Solubility in Water Melting (kg/kg H2O, 25oC) Point (oC) NaF 0.042 988 NaCl 0.357 801 NaBr 1.16 755 Nai 1.84 651 a) Explain the decreasing melting point from NaF to Nai. b) Explain th

Chemical Bonding

1. Consider you would expect a BeF2 molecule to be linear but an SF2 molecule to be angular. 2. a) How would you designate the hybrid orbitals formed by "mixing" one d one s and two p orbitals? b) How many of the hybrid orbitals would be formed by the mixing? 3. Explain why C20H40 is a solid at 25oC, while C4H8 is a gas

Descriptive Chemistry

1.Write equations for the neutralization reactions that result in the formation of the following salts: a) lithium carbonate b) copper (II) chlorate c) aluminum sulphate d) ammonium iodide 2.For each of the following situations, identify those for which a reaction is likely to occur. For those that do occur, write a net

Molecular Formulas of Different Compounds

1. A compound containing titanium (Ti) and chlorine is analyzed by converting all the titanium into 1.20g of TiO2 and all the chlorine into 6.45g of AgCl. What is the simplest formula for the original compound? 2. Estrone is a female sex hormone that is known to contain 80.0% carbon, 8.2% hydrogen, and the remainder oxygen. I

Chemistry language

Can you please assist me with these problems? 1.Write the correct formula for each of the following manganese (II) iodine 2. Write the correct formula for each of the following ions flourate 3. Name the following compounds: a) BaHPO3 b) AgIO 4. Balance the following equations: i)PbCl2+AgNO3 → AgCl+

Chemistry Questions: Gases and Gas Reactions

A balloon contains 400cm3 of helium at 25 degrees and 1 atm pressure. If the balloon bursts when the volume exceeds 800cm3: a) What would be the maximum temperature it could withstand at constant pressure? b) What would be the minimum pressure it could withstand at constant tempersture? c) What height above sea level would

Food Chemistry and Reactions

1. What unusual aspect of water is responsible for it unique characteristics as both a liquid and as a solid? Give examples of how this property of water would affect food systems during processing. 2. The value of ∆G tells use what about chemical reactions? Give three situations and examples. 3. Chemical potential (μi)

Chemistry Notation Questions

A) Provide the type of measurement (volume, length, temperature etc.) for the following units: i) 298 K ii) 65 mL iii) 15 m iv) 290 kg v) 50 g b) Write the following measurements in scientific notation: i) 150000000 kg ii) 0.28 L iii) 0.00004 m c) Answer wheth

Lewis Structures and VSEPR (valence shell electron pair repulsion)

Lewis Structures and VSEPR (valence shell electron pair repulsion). See attached file for full problem description. 1. Listed in the attached document are electron dot formulas for several simple molecules and ions. All valence electrons are shown; however, electrical charges have been omitted deliberately. Which of the

Sigma (σ) and pi (π) bonds

1. How many sigma (σ) and pi (π) bonds are in each of the following molecules? Molecule Number of σ bonds Number of π bonds Molecule Number of σ bonds Number of π bonds CO2 XeF3+ N2 Cl2CO CO32- ion BrO3_ 2. An iron atom is located in a molecule called an "iron-porphyrin" (or "heme") which has an import

Mayonnaise Water and Salt in Water

1. Is the mayonnaise water soluble? 2. While making rice, a housewife adds too much salt to a pot containing rice and water and then brings the pot to a boil. Immediately realizing her mistake she decides to add more water to the pot believing this will remedy the mistake. What do you think? Will her mistake be rectified by a