# Gchem Ques

Discussion in 'DAT Discussions' started by Rock23, Aug 12, 2006.

1. ### Rock23 Member 2+ Year Member

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Can anyone show me how to work this problem:

How many grams of NaOH (40g/mol) are there in 250ml of 0.4 M NaOH solution?

2. ### allstardentist All-Star 10+ Year Member

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.250L of soln x .4mol NaOH/1L solution x 40g of NaOH/1 mol = the answer.

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3. ### Harley comic Junior Member 2+ Year Member

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Because M or Molarity = Mol of solute/kg of solvent. 1000ml = 1 kg
Mol =(Molarity)*(kg of solvent)

Just in case you wonder how to get the answer

4. ### ernest1284 Junior Member 5+ Year Member

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thats actually molality.... molality(m) = molessolute/kg solvent
MOlarity is M so to do the problem (.250L)*(0.4M)=0.1000moles

0.100moles*(40grams/1mol)=4.0grams

5. OP

### Rock23 Member 2+ Year Member

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thanks allstar for the help!

6. ### allstardentist All-Star 10+ Year Member

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no problem

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7. ### Harley comic Junior Member 2+ Year Member

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Thanks for the clarity. I alway messed up
these two guys,
Molarity and molality

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