Gchem Ques

[Rock23]

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?

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[allstardentist]

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

 

[Harley comic]

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

 

[ernest1284]

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

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

 

[Rock23]

thanks allstar for the help!

 

[allstardentist]

no problem

 

[Harley comic]

no problem

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