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Need help on 2 chemistry questions.


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I cannot do these questions. Could someone please explain?

 

Q1) If you have a solution of 1L of H2O and 234g of NaCl, what is the osmotic pressure at STP (R-0.1 l*atm/mol*K)?

a)89.54 atm b)109.2atm c)119.2atm d)218.4atm e)234.0atm

 

 

Q2) What volume of HCl was added if 20 mL of 1M NaOH is titrated with 1M HCL to produce a pH=2?

 

Thank you guys in advance.

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Q1:

Osmotic pressure=MRT, where M is molarity, R is constant, T is temp in K

 

There's 4 moles of NaCl, but NaCl dissociates in water so there's actually 8 moles of particles. R is given as 0.1, and T is 298 since it's STP

 

OP=(8)(298)(0.1)=218.4

 

Q2:

pH=2, so the concentration of H+ is 0.01.

It says 20mL of 1M NaOH, which is 0.02 moles of OH.

 

Therefore you needed to add 0.03 moles of H+ which is 30mL of HCl.

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