How many grams of urea [(NH2)2CO] must be added to 400 g of water to give a solution with a vapour pressure 2.50 mmHg less than that of pure water at 30°C? (The vapour pressure of water at 30°C is 31.8 mmHg.)

A solution of ethanol CH3CH2OH and water that is 10.% ethanol by mass is boiling at 98.7°C. The vapor is collected and cooled until it condenses to form a new solution.

Calculate the percent by mass of ethanol in the new solution. Here's some data you may need:

Be sure your answer has the correct number of significant digits.

Note for advanced students: you may assume the solution and vapor above it are ideal.

Write down the series of oxygen-only chemical reactions relating to the formation and destruction of ozone in the stratosphere. Describe the role of each individual reaction and indicate how Chapman could use them to explain the existence of a stratospheric ozone “layer”.

Describe what is meant by the term “greenhouse effect”. Indicate which species make the greatest contribution and describe their natural and manmade sources. Explain why the major components of air are ineffective greenhouse gases.

In a 4.50L sealed, evacuated flask, Robert injected 2.25g of liquid water and then heated it up to 50.0°C, while measuring the p inside. When the system stabilised, p total = 196.0mmHg. What percentage of water remains as liquid in the flask?

Surfactants form inverse micelles in nonpolar solvents.

a) Why?

b) Why is it difficult to determine the CMC of a surfactant in a nonpolar fluid by measuring its surface tension?

How can you distinguish polyethylene from polypropylene based on their spectra? Give specific differences both in the C-H region and in the C-C region. What functional group is this attributed to in its structural formula? 7. Ignoring the intensities and considering only the number of peaks in the C-H region, compare the spectra of polyethylene and polypropylene with polyvinyl chloride. Formulate a hypothesis relating the C-H region of the spectrum to the polymer structure (specifically, consider the hydrogen atom environments). Support your hypothesis with evidence from these three polymers.

An aqueous solution contains 5.8% KBr by mass.

Calculate the molality of the solution.

Calculate mole fraction of the solution.

Please help

An unknown molecule contains only sulfur atoms. Suppose 1 L of vapor of this 20) molecule is reacted with sufMicient oxygen at 1 atm and 500 °C to produce 8 L of SO2 gas. How many sulfur atoms does the unknown molecule contain in the vapor phase?

A) 8 B) 3 C) 2 D) 4 E) 6

If one mole of water (~18 mL, the system) is vaporized from liquid to gas at 100o C, the amount of work done on the surroundings is 2.5 kJ, while the change in internal energy for the system is 38.2 kJ/mol. What is the amount of heat required to vaporize one mole of water?

A) 38.2 kJ B) 35.7 kJ C) O40.7 kJ D) 40.7 kJ E) O35.7 kJ

One mole of an ideal gas is expanded from a volume of 1.00 L to a volume of 10.00 L against a constant external pressure of 1.00 atm. How much work (in joules) is performed on the surroundings?

A) 456 J B) 912 J C) 0.013 J D) 2740 J E) 2870 J

PLEASE SHOW WORK

can someone provide me the constitutional isomers of c5h12f2? can you also provide the name of the isomers? Thank you so much

Consider the titration of a 28.0 mL sample of 0.175M CH3NH2 with a 0.145M HBr. Determine each of the following.

I already got initial pH: 11.94 and the volume of added acid required to reach equivalence point: 33.8 mL.

I still need help with these:

1. The pH of 4.0 mL of added acid.

2. The pH at one-half of the equivalence point.

3. The pH of the equivalence point.

4. The pH after adding 4.0 mL of acid beyond the equivalence point.

This is all one question, but it is broken into several parts.

What is the difference between Raman scattering and IR absorption? Explain it using an energy diagram.

What is a difference between the Stokes Raman and the Anti-Stokes Raman scattering?

What does “Raman Shift” mean?

What is the major compound that comprises the top coating layer of an Excedrin tablet?

Draw the chemical structures of the three APIs contained in an Excedrin tablet.

You need to increase the dissolution rate of a slightly water soluble drug in tablet form. Propose three different solutions to this problem and explain why each of your solutions will solve the problem. (note that making a prodrug is not an option).

Given a 0.1 M NH4Cl solution: a) Which is the pH of this solution? b) If 100 mL of 0.1 M HCl solution are added to 100 mL of the original solution, which is the pH? c) And if 100 mL of 0.1 M NH3 are added to 100 mL of the original solution? Data: kb(NH3 ) = 1.8 10^-5 .