Engine Performance
Work Example 12

WorkKey Level: 5
NATEF Automotive Tasks: VIII.D.4

Excessive alcohol (over 10%) will cause drivability problems.  You have a beaker with one milliliter of tap water and ten milliliters of fuel from a car's gas tank.  After thoroughly mixing the two liquids and letting them settle, you find that the water level is 0.75 milliliters higher than it originally was.  What is the percentage of alcohol in the fuel?  Allowing up to 10% alcohol on gasoline, is this acceptable?  Note: Water will extract alcohol from fuel.

Solution:

1.75 ml water/alcohol mixture –1.00 ml water   0.75 ml alcohol fuel

(Alcohol taken out)/(Original amount of fuel) = 0.75 ml/10 ml = 0.075 = 7.5%

Since 7.5% < 10%, yes this is an acceptable amount.

* Automotive teacher can do a demonstration for further clarification, if needed.