Calculating the density

[Zhaoyang]

Hi, everyone,

I want to calculate the solution density where 1 g NaCl is added to 1kg water at 20°. However, I got a density samller than 1 g/cm^3. Does anyone provide some help to me? Thanks a lot in advance.

Code: [Select]

SOLUTION 1
    temp      20
    pH        7
    pe        4
    redox     pe
    units     mmol/kgw
    Na        17.112
    Cl      17.112
    -water    1 # kg
END
Best regards,
Zhaoyang

[dlparkhurst]

Whereas the mass of solution will increase with the addition of solutes, the volume of solution may decrease or increase with the addition of solutes. So density, mass/vol, may increase or decrease.

Just an obscure point, but the following code implements your description more exactly. It doesn't matter in this calculation because NaCl does not hydrolyze by forming ion complexes that consume water. However, if hydrolysis did occur, your SOLUTION definition has 1 kg water after hydrolysis, whereas the following has 1 kg water before any hydrolysis.

Code: [Select]

SOLUTION 1
    temp      20
    pH        7
    pe        4
    redox     pe
REACTION 1
NaCl 1
0.017112 mol
END