Group 11, Period 1 : Recrystallization Experiment CPIPS 2013 by Di Chau [Student FVHS]

If your percent error was negative, what logical sources of error might have been the cause? Explain. Answer this question regardless of what your results were.

17chaucd096 — 2013-11-14 16:50:02 UTC

If our percent is positive, then it means that there are more grams of salt then what we started out with. A logical explanation for the gain of mass is that there still may be some water still absored in the salt and cup and has not all evaporated yet.

If your percent error was positive, what logical sources of error might have been the cause? Explain. Answer this question regardless of what your results were.

17chaucd096 — 2013-11-14 16:50:18 UTC

If our percent is positive, then it means that there are less grams of salt then what we started out with. A logical explanation for the loss of mass is that the salt may have escaped from the beaker and landed on the table. Another explanation is that some salt may have been stuck on the watch glass that is covering the beaker.

Trial 1 Calculations

17chaucd096 — 2013-11-18 17:31:45 UTC

Trial 2 Calculations

17chaucd096 — 2013-11-18 17:36:20 UTC

Materials: 1-2 grams, of NaCl, several pieces of glassware, heating plate, electronic balance, about 25 mL of water

17chaucd096 — 2013-11-19 16:20:20 UTC

Second item was supposed to be a watch glass, but ~~panorama~~ I messed up

Which ESLR or ESLR's were adressed in the activity? State the ESLR and explain why in a short paragraph.

2013-11-19 16:30:35 UTC

In this activity the ESLR adressed was Critical Thinker. While doing this activity we had to try to figure out where the missing/extra salt went and how we gained/lost it. This caused us to ponder and question how this was possible.

Data Table

17shehadehsh317 — 2013-11-19 16:37:05 UTC

Trial #1

A	. Mass of salt (NaCl) used.	1.30g
B	. Mass of empty beaker before you start	142.61g
C	. Mass of beaker with recrystallized NaCl	143.91g
D	. Mass of recrystallized NaCl (C minus B)	1.30g
E	. Volume of water added to dissolve NaCl	25.00mL

Trial #2

A.	Mass of salt (NaCl) used	1.84g
B.	Mass of empty beaker before you start	142.61g
C.	Mass of beaker with recrystallized NaCl	144.65g
D.	Mass of recrystallized NaCl (C minus B)	1.99g
E.	Volume of water added to dissolve NaCl	25.00mL

Trial #3

A	. Mass of salt (NaCl) used	1.29g
B.	Mass of empty beaker before you start	142.59g
C.	Mass of beaker with recrystallized NaCl	143.78g
D.	Mass of recrystallized NaCl (C minus B)	1.21g
E.	Volume of water added to dissolve NaCl	25.00mL

Trial 3 Calculations

2013-11-19 16:43:58 UTC

Pre Lab Discussion:

17chaucd096 — 2013-11-19 16:54:19 UTC

Recrystallization is one way of isolating an ionic compound from a solution. If several ionic compounds are present in an aqueous solution, then a precipitation reaction may be performed to remove the unwanted ions. In this experiment, a known amount of NaCl will be dissolved in some water, and then recrystallized by boiling off the water.

Purpose: We will learn to

17chaucd096 — 2013-11-19 16:55:10 UTC

To perform and master a recrystallization of an ionic compound

To write a procedure for a simple experiment

To calculate for percent error in an experiment

To understand how results affect percent error

To identify sources of error in experiments