1.Given the following mole fraction and vapor pressures for miscible liquids A and B, calculate the composition (in mole percentage) of the vapor from a distilling an ideal binary solution at 150°C and 760 mmHg for the solution

X_A=0.50                        P_A=1710mmHg

X_B=0.50                        P_B=130mmHg

2. Define the following.

Refluxing

Dalton’s Law

Raoult’s Law

3. What is the mole fraction of each component if 4.0 g of benzene (C₆H₆) is dissolved in 6.4 g of toluene (C₇H₈)?

4. Consider the following solvent pairs. If mixed together, which pairs would form two layers? If they form two layers, which solvent would be on top?

Acetone and toluene

Methanol and hexanes

Hexanes and methylene chloride

Hexanes and water

5 .Chloroform is an excellent solvent for extracting caffeine from water. The distribution coefficient K_D=(C chloroform)/(C water) for caffeine in chloroform- water is 10 °C at room temperature. Find the mass of caffeine that would be removed from a solution 4.0 g of caffeine in 100ml of water using a single extraction of 100 ml of chloroform.

Calculate the pH of a solution that contains .03 g of NaH2PO4*H2O and .01 g of Na2HPO4*7H2O in 10 mLs.

QUESTION 6 Complete combustion of 4.5892 a particular compound that contains only carbon, hydrogen and oxygen produces 10.4324 g of CO2 and 4.2705 g of H2O. The empirical formula of the compound is given by

C__________________ H______________________ O_____________ (indicate "1" if there is only one atom of a given type in the empirical formula.)

The molar mass of the compound is found to be 116.16 g/mol in a different experiment. What is the molecular formula of the compound?

C______________ H________________ O_____________________

Need help and answers please!

In the qualitative analysis scheme, magnesium and nickel precipitate from solution upon the addition of sodium hydroxide. Once separated from the remaining cations by filtration or decanting, the solid mixture is acidified and warmed to dissolve magnesium and nickel cations back into solution. Adding ammonia creates a buffer solution. (Remember, HCl and NH3 makes for NH4+ cation.) The buffered solution should just be basic (say, pH = 8). Adding sodium hydrogen phosphate (Na2HPO4) precipitates magnesium as MgNH4PO4 (Ksp = 3 x 10-13).

a) Write the Ksp expression for the dissociation of MgNH4PO4.

b) Calculate the molar solubility of the compound in pure water.

c) Calculate the [NH4+] in a pH of 8.

d) Calculate the molar solubility of MgNH4PO4 in a solution with pH of 8.

protein molecules are polypetide chains are made up of amino acids in their phisologically functoning or native state these chains fold in a unique manner such that the nonpolar groups of the amino acids are usually burired in the interior region of the proteins where there is little or no contact with water. when a protein denatures the chain unfolds so that these non polar groups are exposed to water. a useful estimate of the changes of the thermodynamic quantities as a result of denturation is to consider the transfer of hydrocarbon such as methane from an invert solvent to the aqueous enviroment: a) CH4 => CH4 ​(g) b) CH4​=> CH4 (aq) if the values of delta H and delta G are approximately 2.0 kJ/ mol and -14.5 kj/mol respectively for (a) and -13.5 kJ / mol and 26.5 kJ/mol , respectively for b) calulate the values of delta H and delta G for the transfer of 1 mole of CH4 ​according to the equation CH4 =>CH4 (aq) comment on your results assume T = 298 k

A quantity of 6.732 g of an organic compound is dissolved in water to make 270.0 ml of solution. The solution has an osmotic pressure of 1.43 atm at 27 C. The analysis of this compound shows that it contains 41.8% C, 4.7% percent H, 37.3% O, and 16.3% N. Calculate the molecular formula of this compound

I have to write out a lab plan for an upcoming experiment! and complete the table below

Experiment 9: Introduction to Acids, Bases, and pH Learning

Objectives

» to gain experience with a wide variety of acids and bases

» to learn how to predict the principal species in a solution

»to learn how to measure acidity, basicity, and pH

» to predict what will happen when different acid and base solutions are mixed

Be sure to record all data in your own notebook. Materials Lots of acids and bases in various concentrations, litmus paper, well plates and pH meters.

Introduction to Acids and Bases Acids and bases are all around us. They are present in the fruits and vegetables we eat, in the sodas we drink, and in the various commercially available products that we use to unclog our kitchen sinks! Acids are characterized with respect to their ability to produce hydronium ions (H3O + ). Bases are characterized with respect to their ability to produce hydroxide ions (OH– ). Both acids and bases can be classified as “strong” or “weak,” which are allusions to whether the species is a strong electrolyte (placing many ions in solutions, see (1) below) or a weak electrolyte (placing a small number of ions in solution, see (2), below). (1) HCl(aq) + H2O()  H3O + (aq) + Cl (aq) Production of hydronium ion by a strong acid (2) NH3 (g) + H2O() NH4 + (aq) + OH (aq) Production of hydroxide ion by a weak base Strong acids produce large amounts of hydronium ions because their reaction with water goes essentially to completion, thus producing a stoichiometric number of ions. Weak acids react with water in the same type of proton-transfer process, but the equilibrium constant is not as large and only a minimal number of ions are created. The same can be said for strong and weak bases with respect to the amount of hydroxide formed. The chemical structure of the acid or base plays a large role in its ability to lose or attract a proton. 9-2 Introduction to Acids, Bases and pH In order for you to predict the principal species in solution, you must know if a particular acid or base is strong or weak. It is best to just memorize the strong ones: Strong Acids HCl hydrochloric acid HBr hydrobromic acid HI hydroiodic acid HNO3 nitric acid HClO4 perchloric acid H2SO4 sulfuric acid Strong Bases NaOH sodium hydroxide KOH potassium hydroxide Strong acids and strong bases are strong electrolytes; their principal species in solution are the fully dissociated ions – H3O + , Br– NO3 – , ClO4 – , HSO4 – , Na+ , K+ , OH– , etc. IT IS CRITICAL THAT YOU MEMORIZE THE NAMES AND FORMULAS OF THESE STRONG ACIDS AND BASES AND ALSO KNOW WHAT IONS THEY PRODUCE. DO IT NOW. Pretty much anything else that has a name that ends with “acid” – hydrofluoric acid, acetic acid, formic acid, nitrous (rather than nitric) acid, phosphoric acid, etc. – is a weak acid. Just about anything else containing nitrogen in it is a weak base. Weak acids and weak bases are weak electrolytes. Their principal species in solution is just themselves. The lower the pH of a solution, the more acidic it is. Conversely, the higher the pH of a solution, the more basic it is. A pH of 7 indicates that the concentrations of H3O + and OH– are equal; such solutions are called “neutral.” Acids and bases react with each other to form neutral solutions with salts and water as the products. (Can you write the reaction equation between HCl and NaOH?) Salts in solution will also form acidic, basic or neutral solutions depending on the properties of the ions. This will be apparent in some of the work carried out in today’s experiment.

Procedures Part 1: Acid, Base, or Neutral?

Types of substances in this table include neutral salts, strong acids, strong bases, weak acids (might be a salt), and weak bases (might be a salt). Water is present in large quantities in any aqueous system, so you need not list H2Omolecules as a principal species.

Solution Type of Substance Principal Specie(s) in Solution Prediction Measured pH

a 0.1 M HCl Strong acid H3O + , Cl– acidic

b 0.1 M H3PO4 Weak acid

c 0.1 M CH3CO2H Weak acid

d 0.1 M NH4Cl Salt (acidic) NH4 + , Cl–

f 0.1 M NaCl Salt (neutral) Na+, Cl– neutral

g 0.1 M NaO2CCH3 Salt (basic)

h 0.1 M NH3 Weak base NH3

i 0.1 M NaOH Strong base

When you get to lab, discuss your predictions with your partner and try to come to a consensus on your best guesses. Then measure the pH of each solution using a pH meter (Read the pH Meter Blue Pages! The use of these meters will also be demonstrated for you.) Record your predictions and observations in tabular form in your notebook. Note any surprises, as you will need to explain them later!

A 250.0-mL buffer solution is 0.290 molL−1 in acetic acid and 0.290 molL−1 in sodium acetate.
Ka(CH3COOH)=1.8×10−5

Part A

What is the initial pH of this solution?

Express your answer using two decimal places.

Part B

What is the pH after addition of 0.0150 mol of HCl?

Express your answer using two decimal places.

Part C

What is the pH after addition of 0.0150 mol of NaOH?

Express your answer using two decimal places.

3) What 2 effects does an impurity have on the melting point of a solid?

When a molecule absorbs a photon, what is the process called? When a molecule produces a photon, what is the process called?

List the stabilizing forces at tertiary level of protein structure. An enzyme containing the amino aspartic acid (pK_a of the side chain = 3.65) and histidine (pK_a of the side chain= 6) in the active (catalytic ) site has an optimal activity at a pH of 5.0. What is the major stabilizing force at the catalytic site? Using structures and 1-3 complete sentences, predict and explain what is expected to happen to the activity if the pH is increased to 8.

"please answer in details"

A steel sample weighing 1.000 g is dissolved in acids and treated with persulfate and periodate to oxidize Mn to MnO₄^- and Cr to Cr₂O₇^-. The solution is finally diluted to 100.00 mL in a volumetric flask. An aliquot placed in a 1.00-cm cuvette yielded an absorbance of 0.113 at 440 nm and of 1.304 at 545 nm. The absorbance for a reagent blank was 0.005 at 440 nm and 0.008 at 545 nm. Calculate the percentages (m/m) of Cr and Mn in the steel. The molar absorptivity of Cr₂O₇^- is 369 M^-1cm^-1 at 440 nm and 11 M^-1cm^-1 at 545 nm whereas that of MnO₄^- is 95 M^-1cm^-1 at 440 nm and 2350 M^-1cm^-1 at 545 nm. The molar mass of Mn is 54.94 g/mol and that of Cr is 52.00 g/mol.

Calculate the percent ionization in each of the following solutions. a.) 0.10 M NH₃ b.) 0.010 M NH₃

Consider the following reaction:
2SO2(g)+O2(g)→2SO3(g)

What is the theoretical yield of SO3?

If 188.5 mL of SO3 is collected (measured at 327 K and 54.5 mmHg ), what is the percent yield for the reaction?

The first reaction in the Ostwald process for the production of nitric acid involves the combustion of ammonia
4NH3(g)+5O2(g)=4NO(g)+6H2O(g)

a) Estimate ΔH^o (in kJ) for this reaction using average bond energies.

b) Calculate ΔH^o (in kJ) for this reaction using standard heats of formation.

c) Briefly explain why the value for ΔH^o, calculated using average bond energies, is only considered to be an estimate of the standard enthalpy change for the reaction