Question

que cantidad de glucosa tenemos que mezclar con medio litro de agua para que su fraccion molar sea 0,2

Answer 1

Mm C6H12O6 = 180 g/mol
                H2O =  18 g/mol

V = 500 mL

Xglucosa = 0.2

1. calcular g aplicando la fórmula de densidad (D H2O = 1 g/cm3)

d = m/v

m = 1 g/mL  x  500 mL = 500 g

2. calcular moles de agua

n = masa/Mm

n = 500 g/18 g/mol = 27.778 moles de H2O

3. calcular moles de glucosa

X glucosa =         mol glucosa
                   ````````````````````````````````
                    mol glucosa + mol agua

X glucosa ( mol glucosa + mol agua) = mol glucosa
 0.2 ( mol glucosa + 27.778 mol ) = mol glucosa
0.2 mol glucosa + 5.556 = mol glucosa
mol glucosa - 0.2 mol glucosa = 5.556
  mol glucosa(1 - 0.2) = 5.556
  mol glucosa (0.8) = 5.556       despejar mol de glucosa

mol glucosa = 5.556 / 0.8
mol glucosa = 6.94

4. calcular masa de glucosa

n = masa/Mm

masa = 6.94 mol x 180 g/mol

masa = 1249.20 g de glucosa

Kg = 1249.2 /1000 = 1.2492 Kg de glucosa