How Do You Calculate Molar Concentrations and Mass of Solute?

[Aya]

Hi, I need help with this question

what is the molar concentration of 0.50 mol of NaCl dissolved in 0.30L of solution?

=moles of solute/leters of solution
=0.50mol/0.30L
=1.7 mol/L

Is this correct?

and

what mass of solute is present in 1.00L of 0.045 mol/L of Ca(oH)2, solution

I have no idea how to do this one

 

[PPonte]

what is the molar concentration of 0.50 mol of NaCl dissolved in 0.30L of solution?

=moles of solute/leters of solution
=0.50mol/0.30L
=1.7 mol/L

Is this correct?

Yes, it is.

what mass of solute is present in 1.00L of 0.045 mol/L of Ca(oH)2, solution

I have no idea how to do this one

First find how many moles of Ca(OH)₂ there is.
n_Ca(OH)2 = C_Ca(OH)2 x V_solution

Then find the mass of that number os moles:

m_Ca(OH)2 = n_Ca(OH)2 x M(Ca(OH)₂)

M stands for http://en.wikipedia.org/wiki/Molar_mass" .

 

[Aya]

^ ok, thank you