Transcript Salt in Sand Lab

Salt in Sand Lab- Day 2
Mr. Forte & Ms. Shafai’s
Chemistry Classes
Step 1: Get your beakers &
Weigh beaker 2
Get beakers
from the tray
labeled with
your period
(make sure it is
yours)
Find mass and
record mass in
the data table
Beaker 2 ___ g
final mass
Mass of
salt (= to
Beaker 2
final
massbeaker 2
initial
mass)
____ g
Step 2: Weigh Beaker 1
Find mass
and record
mass in the
data table
Beaker 1
final mass
___ g
Mass of
____ g
sand
(=Beaker 1
final Beaker 1
initial- mass
of filter
paper
initial)
Step 3: Observations
Look at your beakers
Describe the contents in each
beaker in your lab notebook
Is there evidence that we have
a pure substance in one or
both beakers? (Write answers
in notebook)
Step 4: Calculate how much
lighter the sand is now
Look at Day 1 Sand Mass (line
e) and subtract Day 2 Final
Sand Mass from it.
Why is there a difference in the
mass of the sand? Where did
the rest of the mass go? (Write
answers to these questions in
notebook)
Step 5: Compare the mass
of sand lost to the mass of
salt
Calculate the difference
between the amount of sand
lost and the final mass of salt
(step 4-step1)
How close are these two
numbers? Where did the
difference in mass go?
Step 6: Calculate percentage
of salt in the original sand
sample
Take your final mass of salt and
divide it by our mass of sand
determined on day 1 (line e).
Write all calculations and label
each component in notebook
(DON’T FORGET SIGNIFICANT
FIGURES!)
Step 7: Clean Up
Dispose of filter and sand in
trash
Rinse both beakers with tap
water (make sure to get salt
out)
Return empty/washed beakers
to tray you got them from
Analysis of Data:
We must measure the
accuracy of our experimental
data
This measurement is called
“percent error”
This value is found by
comparing our experimental
data to a known/given value
Read handout about %
error
Look at and take turns reading
aloud from handout
What is the purpose of
calculating percent error?
Why do we use an absolute
value when calculating the
difference between your result
and the expected? (Write
answers in your lab notebook)
Calculate percent error
Expected results were 4.00 % salt
in sand
Calculate your percent error and
record in your notebook using
the following equation:
% error= I your result - 4.00% I * 100
4.00%
Congratulations- if you got
this far, you do not have
homework!