What is the freezing point of a 50% by volume ethanol solution? Assume water is the solvent. (Use data from Table 12.7 in the textbook.)

For water:

Kb = 0.512 °C m−1

You have completed a reaction and take the melting point of your resulting solid product and the melting point you measured on the melt-temp is 130 – 142°C. The product you were trying to make was chloramphenicol which has a literature melting point of 150 - 151.5°C.

(A) What are two possibilities for why your melting point is different from the literature melting point?

(B) How would you figure out which of your two possibilities actually happened?

Step by Step

Given the following analysis of ground water:

Ca²⁺    43.12 mg/L          SO₄^2-     13.22 mg/L

Na⁺     87.15 mg/L          Cl^-         123.89 mg/L

K⁺       3.22 mg/L           HCO₃^-   213.7 mg/L

Mg²⁺   15.22 mg/L          NO₃^-     3.23 mg/L  

Fe²⁺ 2.13 mg/L            pH       8.3

(A)   Convert all values to meq/L.

(B)    Do an anion-cation balance.

(C)   Plot the position on a trilinear diagram (below)

(D)   Make a Stiff pattern of the analysis (on regular graph paper)

(E)    Make a Schoeller diagram of the analysis (use semi-log)

At 25 ∘C the reaction from Part A has a composition as shown in the table below.

What is the free energy change, ΔG, in kilojoules for the reaction under these conditions?

Express your answer numerically in kilojoules.

a.) Proteins A and B with molecular weight of 16,500 and 35,400 move 4.60 cm and 1.30 cm respectively, during electrophoresis and in SDS-polyacrylamide gel. What is the molecular weight of protein C that moves 2.80 cm under the same conditions in the same gel?

b.) The sedimentation coefficient of a DNA molecule is 22.0 S. A dilute solution of the DNA is spun in a centrifuge at 40,000 rpm starting from a distance of 6.0 cm from the axis of rotation. How far will the DNA move in 20 min?

Calculate the mass of methane that must be burned to provide enough heat to convert 300.0 g of water at 30.0°C into steam at 106.0°C.

50mL of 0.010M NaOH were titrated with 0.50M HCl, added with a dropper pipet. If each drop has a volume of 0.040mL, calculate how many drops of HCl are needed to reach the end-point of the titration.

The vaporization of compound A is described by the given chemical equation.

A(l)⟶A(g)ΔHvap∘=42.69 kJ/mol

Calculate the entropy of vaporization, ΔSvap , for A(l) at 25.0 °C given that the boiling point of A is 78.99 °C , and the molar heat capacity of A(l) is 118.41 J/(mol⋅K) . Assume that the molar heat capacity of A(g) is 53.7% of that of A(l) .

ΔSvap=

J⋅mol−1⋅K−1

Calculate the standard Gibbs free energy of vaporization, ΔG∘vap , at 25.0 °C .

ΔG∘vap=

kJ/mol

Determine the equilibrium constant, K , for the vaporization at 181.0 °C.

K=

Determine the temperature at which the vaporization of A(l) becomes spontaneous. Assume that the enthalpy and entropy of vaporization change very little with temperature.

T=

°C

Is the vaporization of A(l) spontaneous at temperatures greater than or less than T?

less than T

greater than T

34.62 g of ferrous bromide reacts with 29.25 g of potassium chloride in a heated vessel. Write a balanced chemical equation for this double replacement reaction.  What is the percent yield of ferrous chloride if the actual yield is 10.25 g?  How much excess remains?  

Balance the following equation in acidic solution using the lowest possible integers and give the coefficient of water. Cl2(aq) + S2O32- (aq) → Cl-(aq) + SO42-(aq)

use dimensional analysis to solve the following:

a) 789mmHg to atm

b)4.11 tons to Kg

c)6.87 quart to ml

2) A mixture is found to contain 3.17g of SiO2(sand), 6.01g of cellulose, and 7.32 g of calcium carbonate.what is the mass percentage of SiO2 in the mixture? please show a detail explanation.

d) 2.98x 10 to (the fifth power ) yard to Km

Based off these compounds, which one is the most hazardous and why?

Methyl Benzoate

Acetanilide

Nitric Acid (70%)

Acetic acid

Sulfuric Acid (98%)

The stopcock connecting a 1.00 L bulb containing helium gas at a pressure of 554 torr, and a 1.00 L bulb containing krypton gas at a pressure of 504 torr, is opened and the gases are allowed to mix. Assuming that the temperature remains constant, the final pressure in the system is ____torr