Question

Students in Mr. Klein’s chemistry class are conducting an experiment to calculate the specific heat of a copper sample. Mr. Klein requires each lab team to repeat the experiment until their percent error is 2% or less. Percent error is calculated using observed values (those students calculate from their lab results) and the true value (the accepted value based on reference). The formula for percent error is: (observed – true) x 100 true If the accepted value for the specific heat of copper is 0.385 J/g°C, which of the following lab teams have an unresolved problem on their hands
a.

team 1: calculates 0.392 J/gºC
b.

team 2: calculates 0.395 J/gºC
c.

both teams
d.

neither team

Answer 1

Answer is: c) team 2: calculates 0.395 J/gºC.

1) Team 1:

Percent error = (0.392 J/g°C - 0.385 J/g°C) ÷ 0.385 J/g°C · 100%.

Percent error = 0.007 J/g°C ÷ 0.385 J/g°C · 100%.

Percent error = 1.82%.

2) Team 2:

Percent error = (0.395 J/g°C - 0.385 J/g°C) ÷ 0.385 J/g°C · 100%.

Percent error = 0.010 J/g°C ÷ 0.385 J/g°C · 100%.

Percent error = 2.60 %.

Answer 2

Percent error in team 1 value:
(0.392 - 0.385)/0.385  x 100
= 1.81%

Percent error in team 2 value:
(0.395 - 0.385)/0.385 x 100
= 2.60%

B. Team 2 has an unresolved issue in on their hands, resulting in greater than acceptable error.