# What was the most probable cause of error in the following problem?

## To determine the density of corn syrup, a student poured $\text{3.0 mL}$ of the liquid into a $\text{10.0 mL}$ graduated cylinder massed the cylinder and contents. He determined the density to be ${\text{10.5 g/cm}}^{3}$. The accepted value for the density of corn syrup is ${\text{1.38 g/cm}}^{3}$.

May 18, 2017

It appears that the student failed to tare the mass of cylinder before pouring the corn syrup into the cylinder.

#### Explanation:

It is most likely that the mass used to determine the density was the combined mass of the 3 ml of corn syrup and the mass of the cylinder. A density of 10.5 g /ml is al more appropriate for a solid metal like lead than a liquid like corn syrup.

The student should have determined the tare mass of the cylinder before pouring the liquid into the cylinder. The the tare mass could then be subtracted from the total mass to find the mass of the liquid.

The error can be corrected by emptying the cylinder cleaning and drying the cylinder then determining the tare mass of the cylinder.
The mass of the cylinder can then be subtracted from the total mass to find the mass of the liquid.

May 18, 2017

He didn't mass the cylinder when it was empty.

#### Explanation:

It looks like the student did not mass the graduated cylinder while it was empty before he poured the corn syrup into it. So the mass of the corn syrup is unknown. He most likely determined the density by dividing the mass of the cylinder plus corn syrup and the volume of the corn syrup.