Enthalpy change and Vapor pressure

[LeEpikia]

Hello! I'm new here and I'm gonna ask some chemistry questions and I would really appreciate if you'll teach or guide me on how to solve or figure out these problems:

 

1. A solution is prepared by mixing 50.0 g of glucose with 600.0 g of water. What is the vapor pressure of this solution at 25°C?

 

2. A solution is made by mixing 50.0 g of acetone and 50.0 g of methanol. What is the vapor pressure of the solution at 25°C? What is the composition of the vapor expressed as a mole fraction? Assume ideal solution and gas behavior.

 

3. In a coffee-cup calorimeter, 100.0 mL of 1.0M NaOH and 100.0 mL. HCl are mixed. Both solutions were originally at 24.6°C. After the reaction, the temperature is 31.3°C. Assuming all solutions have a density of 1.0g/cm3 and a heat capacity of 4.18J/°C g, what is the enthalpy change for the neutralization of HCl by NaOH? Assume that no heat is lost to its surroundings or the calorimeter.

 

 

I am not asking you to answer these questions, just reply to this post and guide me if you happen to know how to solve that, please. Thank you!

[CaptainPanic]

As a chemical engineer, I would typically solve questions 1 and 2 in three different ways, choosing whichever method is the least time consuming, and gives the accuracy I want.

 

1. You could use Raoult's law. And if this is homework, this is the most likely for you. More complicated thermodynamic models exist as well, but if you would be learning those complicated models, you'd certainly know Raoult's law already.

2. You could just google for the vapor pressure of those mixtures, or use other sources for information such as the Chemical abstracts (which is a database for scientific literature). There are thousands of tables which list such things in literature, and if you're lucky, your mixture is reported somewhere (and at the right temperature and concentration) too.

3. You could use some modelling software. This is typically used only at university, or at commercial enterprises.

 

Regarding the last question: all data is there, so again you just have to figure out the right formula. What is enthalpy? (And I don't mean: which symbol is it.... I'm asking you: what does it mean?)

[studiot]

These questions are set at end of school / beginning of university level.

 

As such you will have had substantial grounding in physical chemistry before they were issued.

 

Have you read the homework help rules?

 

http://www.scienceforums.net/topic/75772-read-this-before-posting-in-homework-help/

 

Start with part 1 which is the simplest.

 

What rules or laws do you know that might be pertinent?