Question

1. During a lab activity, students calculate the density of an element to be 7.78 g/cm3. The density listed on the periodic table is 7.13 g/cm3. Calculate the percent error and identify the element.

2. What two sets of units can be used to describe density? Why are they interchangeable?

Answer 1

I'm still working on number two, but for the first one, the percent error is 9.1164095371669, or 9.12 if you round after plugging in the numbers. That's how I did it.

Answer 2

Answer 1) The percent error will be 9.12 and the element is zinc

Explanation : The percent error has the formula as

% error =
`(observed value - theoretical value)/(theoretical value)  X 100`

∴% error =
`(7.78 - 7.13 )/(7.13) X 100` = 9.12 %

And the density seems to be close to that of element Zinc which is 7.140
`g/cm^(3)`

Answer 2) Density has two units as it is defined in terms of mass and volume.

Also, it is a unique property of every element and compound. As the material remains same the density also remains the same. The density is measured in terms of CGS or SI unit. In CGS unit it is g/mL and in SI unit it is Kg/L.

So, in both the cases we tend to multiply 1000 to g it becomes kilogram (Kg) and 1000 unit of mL is liter (L). And it is seen that the value remains the same.