How many mols are in a gram?

Question

I have a chemistry problem thats stumping me.

It asks, KOH is an ionic solid readily soluble in water.

What is its heat of solution in kJ/g?

On my chart, it says:

Substance: KOH (s)

Heat of solution: -57.61

& on the chart the heats of solution is (kJ.mol solute at 25 degrees celcius.

Do i need to know how many mols are in a gram?

How do i do it

Answer 1

The molar mass of KOH is 56 g/mol. K=39 g/mol, O=16 g/mol and H=1 g/mol. 39+16+1=56.

-57.61 Kj/mol  x 1 mol/56 g=-1.029 Kj/g

Answer 2

yes

Answer 3

mol is shorthand for gram-molecular weight.

K has an atomic weight of 39.10

O has an atomic weight of 16.00

H has an atomic weight of  1.008

Adding these together, you get a molecular weight for KOH of 56.108, or 56.11, so 1 mole of KOH has a mass of 56.11 g.

(-57.61 kJ/mol)(1 mol/56.11 g) ≈

- 1.02676980 kJ/g ≈ - 1.027 kJ/g