How many ions form when 39 grams of calcium fluoride are added to excess water? a. 0.50 mol b. 1.0 mol c. 1.5 mol d. 3.0 mol

c. 1.5 mol

Explanation:

n = mass / molar mass = (39.0 g) / (78.07 g/mol) = 0.499 mol ≅ 0.5 mol.

CaF₂ → Ca⁺² + 2F⁻.

Every 0.1 mole of CaF₂ is ionized to 3 ions (1 ion of Ca⁺² and 2 ions of F⁻).

So, 0.5 mol of CaF₂ will contain (3 x 0.5 mol = 1.5 mol) of ions.

Thus, the right choice is "c. 1.5 mol".

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml