Answer:
1.54 moles of pure ethanol are present in 750mL of wine
Explanation:
The sort of concentration 12% by volume, means that in 100 mL of solution (wine) 12 mL are pure ethanol
We use the density of pure ethanol to determine the mass:
Ethanol density = Ethanol mass / Ethanol volume
Ethanol density . Ethanol volume = Ethanol mass
0.789 g/mL . 12 mL = 9.47 g of ethanol
Now we can determine the moles: 9.47 g . 1 mol / 46.06 g = 0.205 moles
Now we can make a rule of three:
In 100 mL of solution (wine) we have 0.205 moles of pure ethanol
Then, in 750 mL of solution we may have (750 mL . 0.205) / 100 = 1.54 moles